Endogenous redox activity in mouse spermatozoa and its role in regulating the tyrosine phosphorylation events associated with sperm capacitation

We investigated the role of endogenous redox activity in regulating the signal transduction pathway leading to tyrosine phosphorylation in mouse spermatozoa. Endogenous redox activity was monitored using a luminol-peroxidase chemiluminescent probe. Chemiluminescence increased in spermatozoa that were actively undergoing cAMP-mediated tyrosine phosphorylation events associated with capacitation and was inhibited in a dose-dependent manner by addition of catalase or diphenylene iodonium, both of which also inhibited tyrosine phosphorylation within the cell at points downstream of cAMP. Excluding bicarbonate from the incubation medium reduced the redox activity of sperm by 80-90% and dramatically reduced tyrosine phosphorylation. This study provides the first evidence that tyrosine phosphorylation associated with capacitation in mouse spermatozoa is redox regulated by a flavinoid-containing enzyme involving mediation by hydrogen peroxide. Bicarbonate regulated the redox activity of mouse spermatozoa, and this regulation may contribute to the impact of this anion on tyrosine phosphorylation during capacitation of mouse spermatozoa

Slender False Brome (Brachypodium sylvaticum, Poaceae), an Invasive Grass New to Ontario, Canada

Brachypodium sylvaticum, Slender False Brome, an invasive Eurasian grass, is reported for the first time in Ontario and eastern Canada from Grey County, southern Ontario. The only previous Canadian record is from Vancouver Island, British Columbia. The species is widespread in the U.S. Pacific Northwest, where it is spreading aggressively throughout much of western Oregon. In the eastern U.S.A., known populations are few and localized, although the species will likely spread

New reactions and reactive intermediates in the pyrolysis of cyclic phosphonium ylides

The authors are grateful to EPSRC and Glaxo-Wellcome (now GSK) for their support of this work through a CASE Studentship to TM.Pyrolysis, either neat or in diphenyl ether solution, results in the conversion of both 4-triphenylphosphoranylidenetetrahydrofuran-2,3,5-trione and 4-triphenylphosphoranylidenetetrahydrothio-phene-2,3,5-trione into 3,5-bis(triphenylphosphoranylidene)cyclopentane-1,2,4-trione. These reactions involve extrusion of CO2 or COS to give 3-triphenylphosphoranylidenecyclopropane-1,2-dione which further loses CO to give triphenylphosphoranylideneketene. The precise way in which these two reactive phosphorus compounds combine to give the observed product has been examined by chemical and isotopic labelling studies. Cyclotrimerization of triphenylphosphoranylideneketene upon thermolysis in diphenyl ether has also been observed for the first time. The erroneous literature interpretation of the 13C NMR spectrum for triphenylphosphoranylideneketene is corrected.Publisher PDFPeer reviewe

Wages and Foreign Ownership: A Comparative Study of Mexico, Venezuela, and the United States

This paper explores the relationship between wages and foreign investment in Mexico, Venezuela, and the United States. Despite very different economic conditions and levels of development, we find one fact that is robust across all three countries: higher levels of foreign investment are associated with higher wages. However, in Mexico and Venezuela, foreign investment is associated with higher wages only for foreign-owned firms — there is no evidence of wage spillovers leading to higher wages for domestic firms. The lack of spillovers in Mexico and Venezuela is consistent with significant wage differentials between foreign and domestic enterprises. In the United States, where the evidence suggests some wage spillovers from foreign to domestic enterprises, wage differentials are smaller

The value of 2 J P–CO as a diagnostic parameter for the structure and thermal reactivity of carbonyl-stabilised phosphonium ylides

A survey of 20 carbonyl-stabilised phosphonium ylides with recently reported X-ray structures shows a strong correlation between the CP to CO torsion angle and the value of 2JP–CO, with high values being associated with an anti configuration and low with syn. Seven new X-ray structural determinations are reported, several for types of ylide not crystallographically characterised before, and these also conform to this pattern. The value of 2JP–CO is then correlated with whether or not thermal extrusion of Ph3PO occurs to give alkynes for over 200 ylides and an empirical rule developed that the extrusion never occurs for ylides where this value is > 11 Hz. This is used to rationalise the anomalous behaviour of some trioxo ylides and cyclic ylides, two of which afford cycloalkynes, isolated after rearrangement as the isomeric 1,3-dienes. The rule also holds for a family of novel highly fluorinated ylides which afford fluorinated alkynes in good yield upon flash vacuum pyrolysis.EPSRC (U.K.) for a DTA Studentship (Grant No. EP/P505712/1

Bipolar Symbiotic Planetary Nebulae in the Thermal-IR: M2-9, Mz3, and He2-104

We present thermal-IR images of three extreme bipolar objects, M2-9, Mz3, and He2-104. They are bipolar planetary nebulae with bright central stars and are thought to be powered by symbiotic binary systems. The mid-IR images spatially resolve the SEDs of the central engines from the surrounding nebulae. A warm dust component of several hundred degrees can account for the core emission, while a cooler component of about 100 K produces the more extended emission from the bipolar lobes. In every case, the dust mass for the unresolved core region is orders of magnitude less than that in the extended lobes, raising doubts that the hypothetical disks in the core could have been responsible for pinching the waists of the nebulae. We find total masses of roughly 0.5-1 Msun in the nebulae of M2-9 and Mz3, requiring that this material was donated by intermediate-mass progenitor stars. The mass of He2-104's nebula is much lower, and any extended emission is too faint to detect in our images. Extended dust around both M2-9 and Mz3 resembles the distribution of ionized gas. Our images of Mz3 have the highest signal-to-noise in the extended polar lobes, and we show that the fairly uniform color temperature derived from our images can explain the 110 K dust component that dominates the far-IR SED. In the case of Mz3, most of the mass traced by dust is concentrated at high latitudes.Comment: accepted by AJ, 18 pages, 5 figure

Beneficial cardiovascular effects of reducing exposure to particulate air pollution with a simple facemask

<p>Abstract</p> <p>Background</p> <p>Exposure to air pollution is an important risk factor for cardiovascular morbidity and mortality, and is associated with increased blood pressure, reduced heart rate variability, endothelial dysfunction and myocardial ischaemia. Our objectives were to assess the cardiovascular effects of reducing air pollution exposure by wearing a facemask.</p> <p>Methods</p> <p>In an open-label cross-over randomised controlled trial, 15 healthy volunteers (median age 28 years) walked on a predefined city centre route in Beijing in the presence and absence of a highly efficient facemask. Personal exposure to ambient air pollution and exercise was assessed continuously using portable real-time monitors and global positional system tracking respectively. Cardiovascular effects were assessed by continuous 12-lead electrocardiographic and ambulatory blood pressure monitoring.</p> <p>Results</p> <p>Ambient exposure (PM_2.586 ± 61 <it>vs </it>140 ± 113 μg/m³; particle number 2.4 ± 0.4 <it>vs </it>2.3 ± 0.4 × 10⁴particles/cm³), temperature (29 ± 1 <it>vs </it>28 ± 3°C) and relative humidity (63 ± 10 <it>vs </it>64 ± 19%) were similar (P > 0.05 for all) on both study days. During the 2-hour city walk, systolic blood pressure was lower (114 ± 10 <it>vs </it>121 ± 11 mmHg, P < 0.01) when subjects wore a facemask, although heart rate was similar (91 ± 11 <it>vs </it>88 ± 11/min; P > 0.05). Over the 24-hour period heart rate variability increased (SDNN 65.6 ± 11.5 <it>vs </it>61.2 ± 11.4 ms, P < 0.05; LF-power 919 ± 352 <it>vs </it>816 ± 340 ms², P < 0.05) when subjects wore the facemask.</p> <p>Conclusion</p> <p>Wearing a facemask appears to abrogate the adverse effects of air pollution on blood pressure and heart rate variability. This simple intervention has the potential to protect susceptible individuals and prevent cardiovascular events in cities with high concentrations of ambient air pollution.</p

Current and future costs of cancer, heart disease and stroke attributable to obesity in Australia - a comparison of two birth cohorts

The obesity epidemic appears set to worsen the morbidity and mortality from leading causes of death in Australia -ischaemic heart disease, stroke and obesity-related cancers. The aim of this study was to compare hospital separations, deaths and direct health costs for middle-aged adults (45 to 54 years) in 2004/05 with those attaining age 45 to 54 years in 2024/25 who were born into an obesogenic environment. Using data from National Health Surveys, prevalence of obesity in 2004/05 was calculated for those born in 1950/51-59/60 and four scenarios were considered to project rates in 2024/25 for those born in 1970/71-79/80: an age-cohort model; a linear trend model; a steady state where rates increase to equal those of the older birth cohort at the same age; and a best case where rates remain at 2004/05 levels. Population attributable fractions were calculated by gender and disease using relative risks of disease from the literature, and applied to hospital separations, deaths, and direct health system costs data to estimate the proportion of each attributable to obesity. In 2024/25 the projected number of hospitalizations of 45 to 54 year olds due to the diseases of interest could be more than halved, over 200 lives rescued and $51.5 million (in 2004/05 dollars) saved if further gains in obesity in the younger birth cohort are halted. Instead, if the worst case scenario is realized there will be a more than doubling in costs (in 2004/05 dollars) compared with those born in 1950/51-59/60

The multi-facets of sustainable nanotechnology : lessons from a nanosafety symposium

An international symposium for nanosafety was held recently at the Nanyang Technological University in Singapore. Topics relating to understanding nanomaterial properties, tools, and infrastructure required for predicting hazardous outcomes, measuring nanomaterial exposure levels, systems approach for risk assessment and public's perception of nanotechnology were covered. The need for a multidisciplinary approach, across both natural and social sciences, for developing sustainable nanotechnology solutions was heavily emphasized. This commentary highlights the major issues discussed and the commitment of the nanosafety research community in Singapore to contribute collectively to realise the vision of sustainable nanotechnology