On the mechanism underlying the action of D-600 on slow inward current and tension in mammalian myocardium

D-600 the methoxy derivative of verapamil, is said to affect the force of cardiac contraction and the slow inward current (LSi) specifically by reducing the membrane conductance for Ca2+ (gsi). However, it is apparent that many effects of D-600 cannot be adequately explained solely by an effect on gsi. We studied the effects of D-600 on membrane current and tension of cat papillary muscle, using a conventional single sucrose gap voltage clamp technique. The results indicate that D-600 not only reduces the maximal Ca conductance but also, depending on concentration and duration of exposure, alters both the kinetics of the Ca-carrying system and the amplitude of the steady state outward current. No changes in the steady state activation and inactivation variables or in the rate of Isi inactivation were found. However, a substantial increase in the time to peak Lsi, as much as 7 times normal, was observed after exposure to D-600 (0.5 X 10(-6) to 2.0 X 10(-6) M) for at least 20 minutes. Because approximately only 75% of the reduction in Lsi induced by D-600 could be attributed to change in the maximum value of gsi (gsi), we conclude that the change in time to peak and about 25% of the reduction in Isi must be due to a change in the activation kinetics of the Ca-carrying system, Calculations suggest that the time to 70% activation of gsi can be prolonged to as much as 10 times normal by prolonged exposure to negatively inotropic concentrations of D-600.     

Control of influenza in the hospital

Nosocomial transmission of influenza has been reported infrequently; however, patients in general hospitals are often among the most susceptible to the complications of influenza infection. Hospital-acquired influenza may occur more often than is reported, but it may be recognized because of lack of diagnostic facilities or the time required for virus isolation and identification. Based on the mode of transmission in the hospital, the established reservoirs of influenza virus, and duration of virus shedding, isolating patients with influenza may occasionally be useful but restricting visitors is probably not required. Vaccinating hospital personnel with influenza vaccine and, if influenza A is prevalent, giving amantadine hydrochloride to high-risk patients or personnel should both be considered.     

Predicted intake of trace elements and minerals via household drinking water by 6-year-old children from Krakow,Poland. Part 5: Zinc

Zinc (Zn) exposure in pre-school children via household drinking water collected by a double sampling method (morning, evening) was evaluated in a sample of the Polish population. Zn concentration was measured by flame atomic absorption spectrometry. Rural and suburban Krakow sites were non-distinguishable in respect of Zn concentrations. However, significantly lower Zn was found in urban as compared with non-urban sites [geometric mean (95% confidence interval) 0.14 (0.01–1.95) mg l^?1 versus 0.52 (0.03–10.2) mg l^?1, p < 0.001.] Zn levels in water standing overnight in pipelines were higher in all sites by 0.36 mg l^?1 on average, but observed really contaminations were higher. The Zn limit based on the taste and colour of drinking water (3 mg l^?1) was exceeded in 1% and 10% of households from urban and non-urban sites, respectively. The Zn intake predictions for evening water samples for 6-year-old children averaged between 2% and 9% of the recommended dietary allowance (RDA, 10 mg day^?1) for urban and non-urban sites, respectively. Mean Zn intake prediction for the exceedance fraction was 64% of RDA. In conclusion, overnight contamination of drinking water from in-house pipelines was significant and common to all sites investigated. Secondly, drinking water can be considered a significant contributor to dietary Zn intake by children in non-urban sites and may shift the population borderline of deficiency.     

Effects of Dam Removal on Tule Fall Chinook salmon Spawning Habitat in the White Salmon River,Washington

Condit Dam is one of the largest hydroelectric dams ever removed in the USA. Breached in a single explosive event in October 2011, hundreds‐of‐thousands of cubic metres of sediment washed down the White Salmon River onto spawning grounds of a threatened species, Columbia River tule fall Chinook salmon Oncorhynchus tshawytscha. We investigated over a 3‐year period (2010–2012) how dam breaching affected channel morphology, river hydraulics, sediment composition and tule fall Chinook salmon (hereafter ‘tule salmon’) spawning habitat in the lower 1.7 km of the White Salmon River (project area). As expected, dam breaching dramatically affected channel morphology and spawning habitat due to a large load of sediment released from Northwestern Lake. Forty‐two per cent of the project area that was previously covered in water was converted into islands or new shoreline, while a large pool near the mouth filled with sediments and a delta formed at the mouth. A two‐dimensional hydrodynamic model revealed that pool area decreased 68.7% in the project area, while glides and riffles increased 659% and 530%, respectively. A spatially explicit habitat model found the mean probability of spawning habitat increased 46.2% after dam breaching due to an increase in glides and riffles. Shifting channels and bank instability continue to negatively affect some spawning habitat as sediments continue to wash downstream from former Northwestern Lake, but 300 m of new spawning habitat (river kilometre 0.6 to 0.9) that formed immediately post‐breach has persisted into 2015. Less than 10% of tule salmon have spawned upstream of the former dam site to date, but the run sizes appear healthy and stable. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.     

Two cooperatively social populations of the theridiid spider Anelosimus studiosus in a temperate region

The quality of an individual's odour can allow potential mates to discriminate against individuals of low social class, poor health status or unsuitable genotype. Competitive scent marking provides a further mechanism which could allow mates to discriminate between individuals of apparently high quality. The presence or absence of fresh countermarks from competitors within an owner's territory or area marked by a dominant animal provides a reliable indicator of the owner's ability to defend its territory or dominate competitors. This could be used by potential mates to discriminate between individuals advertising their apparently high competitive ability through their scent-marking behaviour and odour quality. We tested this by manipulating scent marks in the neighbouring territories of wild-caught male house mice, Mus domesticus. As predicted, oestrous females used scent marks to select males apparently able to defend exclusive territories over those unable to exclude intruders. Females were more strongly attracted to the odour of owners of exclusively marked territories and showed more sexually related behaviour when interacting with these males. Furthermore, while females preferred a territory containing a better protected nest site regardless of the owner's apparent competitive ability, they still used the presence or absence of intruder countermarks when selecting a potential mate. This suggests that females use scent marks as a reliable signal of the best-quality mate among neighbouring males independently of their nest location. Since assessment depends on both the territory holder's own marks and those of competitor males, countermarking is likely to be an important mechanism of competition for mates between neighbours. Copyright 1998 The Association for the Study of Animal Behaviour