Postimpoundment time course of increased mercury concentrations in fish in hydroelectric reservoirs of northern Manitoba, Canada.

Mercury (Hg) concentrations in fish in boreal reservoirs have been shown to be increased for up to 3 decades after impoundment. However, the time course of increased concentrations is not well known. The purpose of this study was to determine the evolution of Hg concentrations in fish in the boreal reservoirs of northern Manitoba, Canada, and its relationship with severity of flooding. We determined total Hg concentrations in three species of fish for up to 35 years after impoundment in 14 lakes and lake basins. Postimpoundment trends depended on fish species and reservoir. In the benthivorous lake whitefish (Coregonus clupeaformis), Hg concentrations increased after flooding to between 0.2 and 0.4 microg g(-1) wet weight compared with preimpoundment concentrations between 0.06 and 0.14 microg g(-1) and concentrations in natural lakes between 0.03 and 0.06 microg g(-1). Hg concentrations in lake whitefish were usually highest within 6 years after lake impoundment and took 10 to 20 years after impoundment to decrease to background concentrations in most reservoirs. Hg concentrations in predatory northern pike (Esox lucius) and walleye (Sander vitreus) were highest 2 to 8 years after flooding at 0.7 to 2.6 microg g(-1) compared with preimpoundment concentrations of 0.19 to 0.47 microg g(-1) and concentrations in natural lakes of 0.35 to 0.47 microg g(-1). Hg concentrations in these predatory species decreased consistently in subsequent years and required 10 to 23 years to return to background levels. Thus, results demonstrate the effect of trophic level on Hg concentrations (biomagnification). Peak Hg concentrations depended on the amount of flooding (relative increase in lake surface area). Asymptotic concentrations of approximately 0.25 microg g(-1) for lake whitefish and 1.6 microg g(-1) for both walleye and northern pike were reached at approximately 100% flooding. Downstream effects were apparent because many reservoirs downstream of other impoundments had higher Hg concentrations in fish than would be expected on the basis of flooding amount.

Use of a monophasic, low-dose oral contraceptive in relation to mental functioning.

The objective of the study was to evaluate the effect of Minulet, a new low-dose oral contraceptive on mood in two groups and to compare the effect with a control group of women not taking oral contraceptives (OC). The women participating were between 16 and 45 years of age. They completed the Amsterdam Mood Questionnaire (AMQ) and the Sickness Impact Profile (SIP) three times. They were filled in before treatment started, after taking Minulet for one month and then again after three months. The questionnaires were filled in by a group of 200 women who had not taken OC before (starters), and by a second group of 370 women who were already taking OC (switchers). A group of 140 women who did not use any OC during the study served as a control group. These women also filled in the same questionnaires, both at the start, and after one and three months. As far as the AMQ was concerned, the switchers appeared in the initial measurement to have significantly higher scores (that is to say, a worse mood) for "tiredness", "depression", "moodiness", "anxiety" and "anger", than those of the starters and the control group. Moreover, the switchers had reduced scores (that is to say, an improved mood) on the AMQ-scales during their use of Minulet compared to their initial use of oral contraceptives. The scores of the starters and the control group on the AMQ-scales remained unchanged on all three measurements. It can be concluded from this that these groups felt as well as they did before.(ABSTRACT TRUNCATED AT 250 WORDS)

PIP: In the Netherlands, researchers compared data on 195 16-45 year old women who had never used oral contraceptives (OS) and started taking the low-dose OC Minulet (75 mcg gestodene and 30 mcg ethinyl estradiol) (starters) with data on 363 16-45 year old women who had used another OC, then began taking Minulet (switchers), and with data on 139 16-45 year old women who had not used and were currently not using any OC (controls) to examine Minulet's effect on mood. Switchers had higher scores on the Amsterdam Mood Questionnaire (AMQ) for tiredness, depression, moodiness, anxiety, and anger (i.e., a worse mood) than both the starters and controls. Yet, after taking Minulet, the same AMQ scores for switchers fell significantly (i.e., an improved mood). On the other hand, the scores of both the controls and the starters were the same for all 3 measurements (before use, 1 month after use, and 3 months after use). Further, the original Sickness Impact Profile (SIP) scores of switchers revealed significantly more problems with emotional behavior, social interaction, and alertness than the controls. Only the initial social interaction score was significantly different compared to that of starters. After using Minulet, the switchers' SIP scores improved, while the SIP scores of the controls and starters remained the same. Therefore, Minulet did not affect the mood of the starters and significantly improved the psychosocial functioning of women who had used other OCs.

[A comparison of the effectiveness of furazolidone and apramycin in the control of colibacillosis in weaned piglets]. / Een vergelijking van de effectiviteit van furazolidon en apramycine tegen colibacillose bij gespeende biggen.

To compare the effectiveness of furazolidone and apramycin (Apralan) in the treatment of oedema disease in pigs, a trial was made on a commercial farm on which colibacillosis was a recurrent problem. Medicated feed containing 100 ppm of apramycin and 400 ppm of furazolidone respectively was given for three weeks after weaning. 112 Piglets were distributed over 10 battery houses at random. Results are summarized in Figure 1.