A New Slant on Weedy Beans

The direct cash loss from weeds is in lowered crop yields. Weeds rob the crop of moisture, nutrients and sometimes light. And they usually mean more trouble and indirect losses- in combining, later weed infestations, etc

Narcolepsy and Cataplexy – a practical approach to diagnosis and managing the impact of this chronic condition on children and their families

Narcolepsy is a relatively common neurological condition affecting the regulation of normal sleep/wake cycles leading to excessive daytime sleepiness (EDS). It is almost certainly under-recognised as it has a prevalence of 20–50 per 100,000 population and most cases have an onset in adolescence. Cataplexy (attacks of muscle weakness often precipitated by strong emotions) is a hallmark of this condition and represents the intrusion of REM sleep into wakefulness. Narcolepsy is caused by destruction of hypocretin producing cells due to an autoimmune process often by an infective trigger. Hypocretin is found in the hypothalamus and plays a role in stabilisation of the transition between wake and sleep states. In establishing a diagnosis a comprehensive history to exclude other causes of EDS, including poor sleep habits, is essential. Primary sleep related conditions such as sleep apnoea should be excluded. Investigations for confirmation of the diagnosis include Actigraphy, Polysomnography (PSG), Multiple Sleep Latency Testing (MSLT) and CSF analysis. The symptoms of this debilitating condition can have a huge impact on a child's life and are often vastly underestimated. The impact of EDS on cognitive function is an important factor in difficulties at school, mood, quality of life and future career opportunities. Advances in understanding the pathophysiology have led to trials of novel treatment approaches. The aim of this article is to briefly summarise the recent advances in understanding and give an overview of this important condition for those who are involved in the care of a child with this disease

A Killer for Weeds in Soybeans

Timely use of the rotary hoe is an effective killer for weeds in soybeams. In this article, three Iowa State College scientists report directly to you on their tests comparing different weed-control methods

Towards Understanding Photodegradation Pathways in Lignins:The Role of Intramolecular Hydrogen Bonding in Excited States

The photoinduced dynamics of the lignin building blocks syringol, guaiacol, and phenol were studied using time-resolved ion yield spectroscopy and velocity map ion imaging. Following irradiation of syringol and guaiacol with a broad-band femtosecond ultraviolet laser pulse, a coherent superposition of out-of-plane OH torsion and/or OMe torsion/flapping motions is created in the first excited 1ππ* (S1) state, resulting in a vibrational wavepacket, which is probed by virtue of a dramatic nonplanar → planar geometry change upon photoionization from S1 to the ground state of the cation (D0). Any similar quantum beat pattern is absent in phenol. In syringol, the nonplanar geometry in S1 is pronounced enough to reduce the degree of intramolecular H bonding (between OH and OMe groups), enabling H atom elimination from the OH group. For guaiacol, H bonding is preserved after excitation, despite the nonplanar geometry in S1, and prevents O–H bond fission. This behavior affects the propensities for forming undesired phenoxyl radical sites in these three lignin chromophores and provides important insight into their relative “photostabilities” within the larger biopolymer

Ultrafast dissociation dynamics of 2-Ethylpyrrole

To explore the effects of ring substitution on dissociation dynamics, the primary photochemistry of 2-ethylpyrrole has been explored using ultrafast ion imaging techniques. Photoexcitation to the S1 state, a πσ* state, in the range of 238 to 265 nm results in cleavage of the N–H bond with an H-atom appearance lifetime of ca. 70 fs. The insensitivity of this lifetime to photon energy, combined with a small kinetic isotope effect, suggests that tunneling does not play a major role in N–H bond cleavage. Total kinetic energy release spectra reveal modest vibrational excitation in the radical counter-fragment, increasing with photon energy. At wavelengths ≤ 248 nm a second, low kinetic energy H-atom loss mechanism becomes available with an appearance lifetime of approximately 1.5 ps and possibly due to the population of higher lying 1ππ* states

Intramolecular thiomaleimide [2+2] photocycloadditions: stereoselective control for disulfide stapling and observation of excited state intermediates by transient absorption spectroscopy

Thiomaleimides undergo efficient intermolecular [2 + 2] photocycloaddition reactions and offer applications from photochemical peptide stapling to polymer crosslinking; however, the reactions are limited to the formation of the exo head-to-head isomers. Herein, we present an intramolecular variation which completely reverses the stereochemical outcome of this photoreaction, quantitatively generating endo adducts which minimise the structural disturbance of the disulfide staple and afford a 10-fold increase in quantum yield. We demonstrate the application of this reaction on a protein scaffold, using light to confer thiol stability to an antibody fragment conjugate. To understand more about this intriguing class of [2 + 2] photocycloadditions, we have used transient absorption spectroscopy (electronic and vibrational) to study the excited states involved. The initially formed S2 (π1π*) excited state is observed to decay to the S1 (n1π*) state before intersystem crossing to a triplet state. An accelerated intramolecular C–C bond formation provides evidence to explain the increased efficiency of the reaction, and the impact of the various excited states on the carbonyl vibrational modes is discussed

Automated electrophysiological and pharmacological evaluation of human pluripotent stem cell-derived cardiomyocytes

Automated planar patch clamp systems are widely used in drug evaluation studies because of their ability to provide accurate, reliable, and reproducible data in a high-throughput manner. Typically, CHO and HEK tumorigenic cell lines overexpressing single ion channels are used since they can be harvested as high-density, homogenous, single-cell suspensions. While human pluripotent stem cell-derived cardiomyocytes (hPSC-CMs) are physiologically more relevant, these cells are fragile, have complex culture requirements, are inherently heterogeneous, and are expensive to produce, which has restricted their use on automated patch clamp (APC) devices. Here, we used high efficiency differentiation protocols to produce cardiomyocytes from six different hPSC lines for analysis on the Patchliner (Nanion Technologies GmbH) APC platform. We developed a two-step cell preparation protocol that yielded cell catch rates and whole-cell breakthroughs of ∼80%, with ∼40% of these cells allowing electrical activity to be recorded. The protocol permitted formation of long-lasting (>15 min), high quality seals (>2 GΩ) in both voltage- and current-clamp modes. This enabled density of sodium, calcium, and potassium currents to be evaluated, along with dose–response curves to their respective channel inhibitors, tetrodotoxin, nifedipine, and E-4031. Thus, we show the feasibility of using the Patchliner platform for automated evaluation of the electrophysiology and pharmacology of hPSC-CMs, which will enable considerable increase in throughput for reliable and efficient drug evaluation

Pulmonary availability of isotretinoin in rats after inhalation of a powder aerosol

Repeated oral administration of chemopreventive retinoids such as isotretinoin over extended periods of time is associated with intolerable systemic toxicity. Here isotretinoin was formulated as a powder aerosol, and its delivery to the lungs of rats was studied with the aim to explore the possibility of minimizing adverse effects associated with its oral administration. Rats received isotretinoin orally (0.5, 1 or 10 mg kg–1) or by inhalation (theoretical dose ~1 or ~10 mg kg–1) in a nose-only inhalation chamber. Isotretinoin was quantitated by high-pressure liquid chromatography in plasma and lung tissue. The ratios of mean area of concentration-vs-time curve (AUC) values in the lungs over mean AUCs in the plasma for isotretinoin following single or repeated aerosol exposure surpassed those determined for the oral route by factors of between two (single low-dose) and five (single high-dose). Similarly, the equivalent ratios for the maximal peak concentrations in lungs and plasma obtained after aerosol exposure consistently exceeded those seen after oral administration, suggesting that lungs were exposed to higher isotretinoin concentrations after aerosol inhalation than after oral administration of similar doses. Repeated high doses of isotretinoin by inhalation resulted in moderate loss of body weight, but microscopic investigation of ten tissues including lung and oesophagus did not detect any significant aerosol-induced damage. The results suggest that administration of isotretinoin via powder aerosol inhalation is probably superior to its application via the oral route in terms of achieving efficacious drug concentrations in the lungs. © 2000 Cancer Research Campaig

Enhanced methane reforming activity of a hydrothermally synthesised co-doped perovskite catalyst

A catalyst for the direct reforming of methane and simulated biogas has been prepared using a green and low temperature hydrothermal method. The nickel and iron co-doped SrZrO3 perovskite shows catalytic activity comparable to 10% Ni/Al2O3, but with an almost 50% saving in nickel content and a significant reduction in unwanted carbon deposition through thermal decomposition of methane and the Boudouard reaction. The use of a catalyst with a low active metal content produced via a hydrothermal route provides an attractive and sustainable method of production of synthesis gas from both methane and biogas for potential use in solid oxide fuel cells