Release of endogenous noradrenaline from an isolated elastic artery

1. The overflow of noradrenaline following field stimulation of vasoconstrictor nerves has been studied in isolated preparations of the guineapig thoracic aorta.2. Stimulation with trains of 3000 pulses at 5 and 25 pulses.s(-1) resulted in mean overflows of 0.15 and 0.17 (ng.g(-1)).pulse(-1) respectively.3. These overflows were not affected by pre-treatment of the aortae with the inhibitor of neuronal amine re-uptake desmethylimipramine (10(-5)M) or with the inhibitors of extraneuronal amine uptake metanephrine (5 x 10(-4)M) or desoxycorticosterone (2.5 x 10(-5)M).4. In contrast, inhibition of monoamine oxidase and catechol-O-methyl transferase with pargyline (1 x 10(-4)M) and tropolone (2.5 x 10(-4)M) caused the mean overflows to be increased to 0.27 and 0.31 (ng.g(-1)).pulse(-1) in response to stimulation at 5 and 25 pulses.s(-1) respectively. Inhibition of either enzyme alone had little effect.5. It is concluded that in the guinea-pig aorta nervously released noradrenaline is inactivated primarily by enzymic metabolism, while neural re-uptake is insignificant. This situation is the reverse of that existing in the uterine artery of the same species.6. Phenoxybenzamine (10(-5)M) also caused pronounced increases in overflow at both high and low frequencies of stimulation. This could be due to an effect of phenoxybenzamine on release of noradrenaline or on some tissue uptake mechanism distinct from the normal neuronal and extraneuronal pathways.7. Calculations based on the overflow at 5 pulses.s(-1) following total enzyme inhibition indicated that a single stimulating pulse liberated 2.1 x 10(-4) of the total transmitter store.

An electrophysiological study of the effects of atropine and physostigmine on transmission to the guinea-pig vas deferens

1. The effects of physostigmine and atropine on transmission to the longitudinal musculature of in vitro preparations of the guinea-pig vas deferens have been examined using intracellular micro-electrodes.2. Atropine (5 x 10(-7) to 10(-6) g/ml.) increased the rate of decay of excitatory junction potentials (EJPs) in response to post-ganglionic stimulation.3. Physostigmine (5 x 10(-6) g/ml.) reduced the mean resting potential of the muscle cells from -60.5 to -51.5 mV and lowered the voltage of post-ganglionic stimulation necessary for initiation of an action potential in the muscle. In some but not all of the cells studied the time course of the EJP was markedly prolonged.4. At concentrations which did not alter the response to post-ganglionic stimulation (5 x 10(-7) to 10(-6) g/ml.), physostigmine caused fully facilitated EJPs to appear with the first pulse of a preganglionic train of stimulation.5. Atropine antagonized all the above effects of physostigmine.6. Physostigmine (5 x 10(-7) to 10(-6) g/ml.) also lowered the voltage of preganglionic stimulation necessary for initiation of an action potential in the muscle. This effect was not antagonized by atropine.7. The results are interpreted as being evidence for the existence of separate cholinergic and adrenergic motor fibres to the musculature of the guinea-pig vas deferens.

Dominant mobility modulation by the electric field effect at the LaAlO3/SrTiO3 interface

Caviglia et al. [Nature (London) 456, 624 (2008)] have found that the superconducting LaAlO3/SrTiO3 interface can be gate modulated. A central issue is to determine the principal effect of the applied electric field. Using magnetotransport studies of a gated structure, we find that the mobility variation is almost 5 times that of the sheet carrier density. Furthermore, superconductivity can be suppressed at both positive and negative gate bias. These results indicate that the relative disorder strength strongly increases across the superconductor-insulator transition.

What price for a year of life? A survey of U.S. and Canadian oncologists

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Background: New cancer drugs are increasingly expensive and raise difficult questions about the magnitude of therapeutic benefit needed to justify their incremental cost. In this context, it is unclear whether oncologists endorse standard thresholds of $50,000 to $100,000 per year of life. Methods: We surveyed 1,379 U.S. and 356 Canadian (Cdn) oncologists and asked how much longer a patient would need to survive metastatic cancer to justify the expense of a new treatment. To determine the stability of attitudes towards cost-effectiveness (CE) we randomized oncologists to receive two different versions of the scenario in which the price of the new treatment was varied (higher versus lower drug cost). In the U.S. survey, oncologists were also randomized to receive surveys in which we varied the provision of contextual information about the CE of several familiar interventions. Both U.S. and Cdn oncologists were asked to indicate what they “thought was ‘good value for money’ expressed as cost per life-year gained (LYG).” Results: Response rate was 57% in the U.S. and 48% in Canada. CE ratios implied by oncologists’ responses differed significantly between the groups randomized to the higher versus lower price of the hypothetical treatment (p < 0.001 U.S., p < 0.0001 Canada), but were independent of randomization to varying contextual information (p > 0.1). The median willingness to pay for a quality-adjusted year of life ranged from $150,000 (for oncologists considering the lower priced drug) to $250,000 (for those considering the more expensive drug) in both countries. Among those who considered the more expensive drug, 25% of respondents implicitly endorsed a CE ratio greater than $600,000 (U.S.) and $500,000 (Canada). In contrast, when asked directly to indicate CE ratios that were good value for the money outside of the clinical scenario, 70% (U.S.) and 64% (Canada) of respondents indicated values of less than $100,000 per LYG. Conclusions: Oncologists responding to our survey provided inconsistent views on how much benefit expensive new drugs should provide to be worthwhile. This suggests that means of eliciting input from physicians that reflect more stable attitudes need to be developed to appropriately inform decision-makers.

No significant financial relationships to disclose.

A survey of U.S. and Canadian oncologists’ attitudes toward the cost, cost-effectiveness (CE), and reimbursement of cancer drugs

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Background: Drug costs and reimbursement issues offer significant challenges to U.S. and Canadian oncologists even though they practice in substantially different health care systems. However, little is known about the attitudes of American and Canadian oncologists towards these issues. Methods: We surveyed 1,379 U.S. and 356 Cdn oncologists to assess their attitudes to cancer drug costs, CE and reimbursement policies. Results: Response rate was 57% in the U.S. and 48% in Canada. Oncologists in both countries stated that patients' “out-of-pocket” drug costs influenced their treatment recommendations (84% U.S., 80% Cdn respondents). Most respondents felt that every patient should have access to effective cancer treatments regardless of cost (66% US; 54% Cdn), while 59% of U.S. and 72% of Cdn and respondents believed that patients should only have access to effective cancer treatments that provided “good value for money.” 70% of U.S. and 64% Cdn respondents felt that <$100,000 per life year gained was a reasonable definition of “good value for money” but less than half of respondents (42% US, 49% Cdn) felt well prepared to interpret and use CE information in their treatment decisions. A majority of respondents (57% US, 69% Cdn) felt government price controls for cancer drugs are needed while a minority felt that more cost-sharing by patients was needed (29% US, 37% Cdn). Most oncologists felt that evaluating whether a drug provides “good value” should be overseen by an independent non-profit agency (57% US, 71% Cdn) or physicians (61% US and Cdn); in contrast, few believed that government (21% US, 33% Cdn), patients (36% US, 37% Cdn) or insurance companies (6% US, 10% Cdn) should determine “good value”. 79% of U.S. and 69% of Cdn respondents felt more use of CE data in coverage and reimbursement decisions is needed. Conclusions: Oncologists in the U.S. and Canada share many similar attitudes to cancer drug costs, CE, and reimbursement policies despite differences in their health care systems. In both countries, oncologists favor more use of CE information.

No significant financial relationships to disclose.

Prevalence of subclinical mastitis and associated risk factors in smallholder dairy cows in Tanzania

A cross-sectional study was carried out on 200 randomly selected farms in each of the Iringa and Tanga regions of Tanzania to estimate the prevalence and risk factors for subclinical mastitis in dairy cows kept by smallholders. Subclinical mastitis was assessed using the California mastitis test (cmt), and by the bacteriological culture of 1500 milk samples collected from 434 clinically normal cows. The percentages of the cows (and quarters) with subclinical mastitis were 75.9 per cent (46.2 per cent) when assessed by the cmt and 43.8 per cent (24.3 per cent) when assessed by culture. Factors significantly associated with an increased risk of a cmt-positive quarter were Boran breed (odds radio [or]=3.51), a brought-in cow (rather than homebred) (or=2.39), peak milk yield, and age. The stripping method of hand milking was associated with a significantly lower prevalence of cmt-positive quarters (or=0.51). The cmt-positive cows were more likely to be culture positive (or=4.51), as were brought-in (or=2.10) and older cows.

Spin dynamics in a superconductor-ferromagnet proximity system

The ferromagnetic resonance of thin sputtered Ni80Fe20 films grown on Nb is measured. By varying the temperature and the thickness of the Nb the role of the superconductivity on the whole ferromagnetic layer in these heterostructures is explored. The change in the spin transport properties below the superconducting transition of the Nb is found to manifest itself in the Ni80Fe20 layer by a sharpening in the resonance of the ferromagnet, or a decrease in the effective Gilbert damping coefficient, showing that the superconductivity affects the macrospin of the ferromagnetic layer. We interpret this in terms of the spin-pumping model.

Relationship between the intensity of physical activity, inactivity, cardiorespiratory fitness and body composition in 7-10-year-old Dublin children

OBJECTIVE

To investigate the relationships between the time spent in specific intensities of activity and inactivity, cardiorespiratory fitness and body composition in children.

METHODS

A cross-sectional study was conducted in a random sample of schools. Height, weight and waist circumference were measured in 224 children aged 7-10 years. Cardiorespiratory fitness was estimated by the 20 m multistage running test, and physical activity was measured over 4 days by the RT3 (a triaxial accelerometer). Time each day spent in moderate and vigorous intensities of activity was calculated.

RESULTS

Twelve schools agreed to participate in the study. Body composition and fitness data were obtained for 224 children and activity data for 152 children. Boys were found to take part in about twice as much vigorous and hard activity as girls (mean (95% confidence interval) 64.3 (53.2 to 75.4) min in boys compared with 37 (33.1 to 40.9) min in girls; p<0.001). In boys there was significant difference between those defined as normal, overweight and obese in the time spent in vigorous activity (p<0.05), but no such difference was found in girls. A significant negative correlation between waist circumference and time spent in vigorous activity (r = -0.31, p<0.05) was found in boys but not in girls. Time spent sedentary was positively correlated with waist circumference in boys (r = 0.33, p<0.01) but not in girls. In both boys and girls there were significant negative correlations between fitness and both body mass index (r = -0.274, p<0.001) and waist circumference (boys: r = -0.503, p<0.01; girls: r = -0.286, p<0.01).

CONCLUSION

In boys, body composition was inversely related to fitness and to vigorous activity and was positively related to inactivity. In girls, body composition was related to fitness but not to specific components of physical activity.

The interaction between sodium alkyl sulfate surfactants and the oppositely charged polyelectrolyte, polyDMDAAC, at the air-water interface: the role of alkyl chain length and electrolyte and comparison with theoretical predictions

The effect of alkyl chain length and electrolyte on the adsorption of sodium alkyl sulfate surfactants and the oppositely charged polyelectrolyte, polyDMDAAC, at the air-water interface has been investigated by surface tension and neutron reflectivity. The variations in the patterns of adsorption and surface tension behavior with alkyl chain length and electrolyte are discussed in the context of the competition between the formation of surface active surfactant/polyelectrolyte complexes and polyelectrolyte/surfactant micelle complexes in solution. A theoretical approach based on the law of mass action has been used to predict the surface effects arising from the competition between the formation of polyelectrolyte/surfactant surface and solution complexes and the formation of free surfactant micelles. This relatively straightforward model is shown to reproduce the principal features of the experimental results.

Investigation of a tuberculosis cluster at a job centre in Manchester, United Kingdom

During the summer of 2005, four cases of active tuberculosis from the same occupational setting were investigated in Manchester, UK. The index case had been diagnosed in December of the previous year. At that stage the closest occupational contacts had been screened, all of whom were assessed as being free from active disease, and none had met nationally recommended criteria for chemoprophylaxis for latent tuberculosis infection (LTBI). In June 2005, two work contacts developed progressive primary extrapulmonary (pleural) TB. Following a detailed risk assessment, the screening programme was widened to include 137 staff who worked at the job centre (employment agency) where the first four cases had been found. This screening programme was based on tuberculin Mantoux testing, CXR and gamma-interferon testing. Of these 137 contacts screened, one additional person was found to have active disease and six others were offered chemoprophylaxis for LTBI. The isolates from the index case and the first two secondary cases were indistinguishable on VNTR-MIRU (variable number tandem repeat - mycobacterial interspersed repetitive unit) typing at 15 loci. No samples were available for testing from the fourth case of active disease. Management of this incident has benefited from the evolving fields of both genotyping and diagnostic testing for LTBI. However, further research into the epidemiological inferences made through genotyping, as well as the significance of a positive gamma-interferon test in assessing the risk of development of active disease, is still required.

Critical current oscillations in strong ferromagnetic pi junctions

We report magnetic and electrical measurements of Nb Josephson junctions with strongly ferromagnetic barriers of Co, Ni, and Ni80Fe20 (Py). All these materials show multiple oscillations of critical current with a barrier thickness implying repeated 0-pi phase transitions in the superconducting order parameter. We show, in particular, that the Co barrier devices can be accurately modeled using existing clean limit theories and that, despite the high exchange energy (309 meV), the large IcR(N) value in the pi state means Co barriers are ideally suited to the practical development of superconducting pi-shift devices.

Influence of the polyelectrolyte poly(ethyleneimine) on the adsorption of surfactant mixtures of sodium dodecyl sulfate and monododecyl hexaethylene glycol at the air-solution interface

The polyelectrolyte poly(ethylenenimine), PEI, is shown to strongly influence the adsorption of the anionic-nonionic surfactant mixture of sodium dodecyl sulfate, SDS, and monododecyl hexaethylene glycol, C(12)E(6), at the air-solution interface. In the presence of PEI, the partitioning of the mixed surfactants to the interface is highly pH-dependent. The adsorption is more strongly biased to the SDS as the pH increases, as the PEI becomes a weaker polyelectrolyte. At surfactant concentrations >10(-4) M, the strong interaction and adsorption result in multilayer formation at the interface, and this covers a more extensive range of surfactant concentrations at higher pH values. The results are consistent with a strong interaction between SDS and PEI at the surface that is not predominantly electrostatic in origin. It provides an attractive route to selectively manipulate the adsorption and composition of surfactant mixtures at interfaces.