Identification of suites of traits that explains drought resistance and phenological patterns of plants in a semi-arid grassland community.

Grassland ecosystems are comprised of plants that occupy a wide array of phenological niches and vary considerably in their ability to resist the stress of seasonal soil-water deficits. Yet, the link between plant drought resistance and phenology remains unclear in perennial grassland ecosystems. To evaluate the role of soil water availability and plant drought tolerance in driving phenology, we measured leaf hydraulic conductance (Ksat), resistance to hydraulic failure (P50), leaf gas exchange, plant and soil water stable isotope ratios (δ18O), and several phenology metrics on ten perennial herbaceous species in mixed-grass prairie. The interaction between P50 and δ18O of xylem water explained 67% of differences in phenology, with lower P50 values associated with later season activity, but only among shallow-rooted species. In addition, stomatal control and high water-use efficiency also contributed to the late flowering and late senescence strategies of plants that had low P50 values and relied upon shallow soil water. Alternatively, plants with deeper roots did not possess drought-tolerant leaves, but had high hydraulic efficiency, contributing to their ability to efficiently move water longer distances while maintaining leaf water potential at relatively high values. The suites of traits that characterize these contrasting strategies provide a mechanistic link between phenology and plant-water relations; thus, these traits could help predict grassland community responses to changes in water availability, both temporally and vertically within the soil profile.

Lying behavior and activity during the transition period of clinically healthy grazing dairy cows.

Lying behavior and activity may provide useful information for the prediction of an imminent calving and the health of transition dairy cows; however, it is important first to understand what constitutes typical lying behavior and activity because this has not been defined for grazing dairy cows during the transition period. Our objective was to describe changes in lying behavior and activity in grazing dairy cows during the transition period using varying phenotypes typical of commercial dairy herds under grazing systems. Behavior data from IceTag or IceQube (IceRobotics, Edinburgh, Scotland) triaxial accelerometers were collected for 310 cow parities from multiparous, mixed-age (mean ± standard deviation; 4.5 ± 1.65 yr), and mixed-breed [Holstein-Friesian (HF), n = 216; and HF × Jersey, n = 94] grazing dairy cows from 4 parent experiments. The IceTags or IceQubes captured lying and activity data during the transition period (-21 to 34 d relative to calving) to allow the calculation of daily lying time (h/d), daily lying bouts (LB; no./d), mean LB duration (min/bout), and the number of steps taken (steps/d). Lying behavior and activity were analyzed using a repeated measures ANOVA during 3 periods: PRE (-21 to -3 d), POST (3 to 21 d), and the day of calving (d 0). Lying time was lower on d 0 (7.25 h/d) compared with PRE and POST lying times (10.3 and 8.58 h/d, respectively), with more frequent LB on d 0 (12.9 no./d) compared with the PRE and POST daily LB (8.15 vs. 7.74 no./d). Cows took more steps POST (4,424 steps/d) compared with d 0 and PRE (4,105 and 2,289 steps/d, respectively). Regression analysis determined that daily lying time decreased substantially from -3 to 0 d (slope = -1.03 ± 0.07 h/d) and from -2 and -1 d for daily LB (slope = 5.09 ± 0.54 no./d), which may be due to the calving event itself but also reflect restlessness. Daily lying time, daily LB, LB duration, and number of steps taken were substantially altered at the time of the calving event in grazing dairy cows. Cows were more active, spent less time lying, and took more steps postcalving compared with precalving, and it appears that this behavior may largely be due to activity associated with twice daily milking. Mean lying behavior and activity measures were more highly variable across individuals than across groups. Information available via activity monitors may contribute to the improvement of individual management of transition dairy cows, and this research provides a benchmark for typical changes in behavior during the transition period in grazing systems.

Controlled covalent modification of epitaxial single layer graphene on 6H-SiC (0001) with aryliodonium salts using electrochemical methods.

Controlled covalent modification of graphene via electrochemically assisted grafting of molecules is expected to be a robust method for tuning the doping levels and work function and therefore enabling the deployment of graphene in photovoltaic and battery applications. By using aryliodonium salts, in particular, bis(4-nitrophenyl)iodonium tetrafluoroborate, the grafting density can be adjusted from 4 × 10(13) to 3 × 10(14) molecules per cm(2). New insights on the grafting mechanism and the reactivity of the graphene are reported here. Clean basal planes were found to have increased reactivity compared to atomic-level point defects (single vacancies). High resolution scanning tunnelling microscopy (STM) shows that some of the grafts present three-fold symmetry, which may indicate that the grafts are pairs of molecules. The point of attachment of the second molecule is under investigation using computational work which includes simulations of the STM images. Elongated as well as extended grafts (larger than 4 nm) are also observed.

Pulmonary sarcoidosis in a 14-year-old boy diagnosed by low-dose CT-guided transthoracic lung biopsy.

Pulmonary sarcoidosis is a rare disease in the pediatric age group, characterized by the presence of epitheloid-cell granulomas. In stage 3 sarcoidosis, pulmonary infiltrates without hilar lymphadenopathy occur. Definitive diagnosis requires a histopathological specimen, which might be difficult to obtain by transbronchial biopsy. Multidetector computed tomography (MDCT)-guided transthoracic lung biopsy (TLB) is a well-established procedure in adults, but has only rarely been applied in children.A 14-year-old boy was admitted to hospital for evaluation of a chronic systemic disease with severe pulmonary manifestation. All investigations, including bronchosopy and bronchoalveolar lavage with microbiological and virological testing, had been negative. MDCT-guided TLB was performed on a 16-section scanner with a low-dose protocol (single slices, 120 kV, 20 mAs), using a 16-gauge biopsy device. The total effective dose was 0.4 mSv for the biopsy procedure. Histopathological examination revealed multiple epitheloid-cell granulomas with giant cells in the absence of microbiological or virological abnormalities. A diagnosis of stage 3 pulmonary sarcoidosis was made and systemic anti-inflammatory therapy was administered, which led to complete remission within weeks. MDCT-guided TLB can be a valuable instrument in assessing pulmonary manifestations of pediatric sarcoidosis, enabling precise histopathological diagnosis and adequate therapy. The use of low-dose protocols can substantially reduce radiation exposure without relevant loss of image information. MDCT-guided lung biopsy should be considered prior to open-lung surgery in selected patients with unclear pulmonary disease.

Quantification of in-stent restenosis parameters in rabbits by Micro-CT.

PURPOSE: The well-defined model of angioplasty and stent implantation in the rabbit aorta is useful in experimental studies of restenosis. This study was performed to evaluate the feasibility of Micro-CT for quantification of in-stent restenosis in a rabbit aortic in-stent-restenosis model. MATERIAL AND METHODS: To induce in-stent restenosis seven female New Zealand rabbits underwent balloon dilation and denudation prior to stenting the abdominal aorta. After six weeks on atherogenic diet, animals were killed and the aorta was perfused with contrast agent. Micro-CT morphometric analysis of balloon and stent injured arteries obtained by 700 transverse sections (voxel size 10 microm) was compared to conventional histological analysis. RESULTS: Intimal hyperplasia was present in stented and balloon injured arteries with a moderate intimal area assessed by Micro-CT and conventional histology (3.91 +/- 0.5 mm(2) vs. 4.18 +/- 0.42; r = 0.9). High significant correlations between Micro-CT image analysis and conventional histomorphometry were obtained for lesion size, size of media, size of lumen and stent area (r = 0.84 to 0.96). CONCLUSION: Micro-CT is feasible for quantitative information about restenosis following balloon angioplasty and stent implantation and has the potential to become a standard technique in many laboratories which will augment serial histology as the reference method for ex-vivo studies of restenosis.

A novel flexible, retrievable endovascular stent system for small-vessel anatomy: preliminary in vivo data.

BACKGROUND AND PURPOSE: This study assessed the in vivo delivery, retrievability, short-term patency, and cellular response to a new flexible endovascular stent system in a rabbit model. The stent is designed for delivery through a microcatheter and is fully retrievable with electrolytic detachment from a delivery wire. METHODS: We successfully deployed nine stents (range of sizes, 2.5-4 mm diameter, 15-35 mm length) in six straight (carotid) and three angled (subclavian) arteries of six Chinchilla Bastard rabbits. Serial imaging was performed by using intravenous digital subtraction angiography (IVDSA), contrast-enhanced MR angiography (CEMRA), time-of-flight MR angiography (TOF), and CT-angiography 3 days and 4 weeks after stent deployment. Subjects were euthenized after 4 weeks (n = 5), and stents were removed for histologic analysis. RESULTS: Stent deployment was feasible in all cases. After initial deployment, all stents could be fully retrieved within the microcatheter. The detachment zone and the distal stent marker were easily visible under fluoroscopy, and final detachment occurred reliably in all cases. We observed no procedural complications. Noninvasive imaging by using IVDSA, MR angiography, and CT angiography was feasible in this stent system and demonstrated all arteries patent and not narrowed at 3 days and 4 weeks, findings that were confirmed by histologic analysis. CONCLUSION: This electrolytically detachable stent is promising as a treatment for intracranial arteries, because it can be delivered through microcatheters small enough for intracranial navigation. It is fully retrievable, thus providing greater control than currently available stents. Noninvasive imaging by using IVDSA, MR angiography, and CT angiography is feasible in this stent system and may be useful for follow-up. Further long-term data are needed.

Analysis of radon-associated squamous cell carcinomas of the lung for a p53 gene hotspot mutation.

Squamous cell lung carcinomas (SCC) from former employees of the Wismut uranium mining company (Saxony, Germany) were obtained from the Stollberg Archive in order to screen for p53 tumour suppressor gene codon 249 arg-->met hotspot mutations, a putative molecular bio-dosimeter of alpha-particle (radon) exposure (Taylor et al (1994) Lancet 343: 86-87; McDonald et al (1995) Cancer Epidemiol Biomarkers Prevent 4: 791-793). Of the 29 archived samples of SCC meeting quality criteria for DNA analysis by polymerase chain reaction (PCR) and Haelll restriction enzyme digestion, two tumours were found that harboured this mutation. DNA sequencing confirmed the presence of a G to T base substitution within the Haelll site spanning codons 249 and 250 of the p53 gene that results in replacement of arginine (wild-type) by methionine at residue 249. When these data are combined with those from our previous study of tumours from the Stollberg Archive in which 50 lung tumours were examined, (including nine SCCs), we conclude that the G-->T (arg-->met) codon 249 mutation prevalence in the Wismut miner cohort is not sharply elevated in lung cancers in general (two mutations/79 tumours), or specifically in SCCs of the lung (two mutations/38 SCC) when compared to data from lung cancer patients with no reported occupational exposure to radon gas.