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Zn serves as a powerful feed additive to reduce post-weaning diarrhoea in pigs. However, the mechanisms responsible for Zn-associated effects on the adaptive immune responses following feeding of a very high dosage of Zn remain elusive. In this study, we examined the T-cell response in gut-associated lymphatic tissues of seventy-two weaned piglets. Piglets received diets with 57 mg Zn/kg (low Zn concentration, LZn), 164 mg Zn/kg (medium Zn concentration, MZn) or 2425 mg Zn/kg (high Zn concentration, HZn) mg Zn/kg feed for 1, 2 or 4 weeks. We observed that feeding the HZn diet for 1 week increased the level of activated T-helper cells (CD4+ and CD8αdim) compared with feeding MZn and LZn (P<0·05). In addition, we observed higher transcript amounts of interferon γ and T-box 21 (TBET) in the HZn group compared with the MZn and LZn groups (P<0·05). A gene set enrichment analysis revealed an over-representation of genes associated with ‘cytokine signalling in immune system’. Remarkably, feeding of a very high Zn dosage led to a switch in the immune response after 2 weeks. We detected higher relative cell counts of CD4+CD25high regulatory T-helper cells (P<0·05) and a higher expression of forkhead box P3 (FOXP3) transcripts (P<0·05). After 4 weeks of feeding a high-dosage Zn diet, the relative CD4+ T-cell count (P<0·05) and the relative CD8β+ T-cell count (P<0·1) were reduced compared with the MZn group. We hypothesise that after 1 week the cellular T-helper 1 response is switched on and after 2 weeks it is switched off, leading to decreased numbers of T-cells.
It is well known that the development of a diphtheria anti-toxin serum evolved in a competitive race between two groups of researchers, one affiliated with Emil Behring in Berlin and Marburg, and another affiliated with Émile Roux in Paris. Proceeding on the basis of different theoretical assumptions and experimental practices, the two groups developed a therapeutic serum almost simultaneously. But the standardized substance they developed took on very different forms in the two countries. In Germany the new serum was marketed in the private sphere and subjected to state regulations, becoming a kind of prototype of industrial medications. In France, however, the same substance was marketed as a gift of science to humanity and distributed through the communal health care system. This article demonstrates how a new medication emerged from the efforts to produce, market, regulate, distribute, and apply it in the two respective countries. It attributes the difference to the negotiations between the respective actors (scientists, industrialists, politicians, officers, and the public) and institutions (firms, academies, private and public institutes, legislative bodies, professional corporations). I develop this argument on three different levels: First, I stress the importance of the institutional foundations of serum production; second, I illustrate the decisive role played by existing “ways of regulating” in the rapid development of new legal statutes; and third, I describe the consequences that flowed from the respective administrative organization of marketing and dissemination. In sum, I explore how an experimental object was transformed into an object of the public health system and stabilized by administrative means.
Epiphytic lichen diversity in a boggy stand of Norway spruce (Picea abies) was studied in the eastern Harz Mountains, northern Germany. Spruce trees at wet sites were affected by forest dieback, whereas trees on drier sites remained unaffected. Lichen diversity was higher on diebackaffected trees than on healthy ones. The foliose lichen Hypogymnia physodes was significantly more frequent on dead trees, whereas the crustose, extremely toxitolerant Lecanora conizaeoides occurred more frequently on healthy trees. Stemflow concentrations of NH⊂4⊃+, NO⊂3⊃-, PO⊂3⊃-, and SO⊂4⊃2- were lower on affected trees. This is attributed to reduced interception from the atmosphere due to needle loss. Cover of H. physodes decreased with increasing mean SO⊂4⊃2- concentration in stemflow. The total of lichen species per sample tree also decreased with increasing SO⊂4⊃2- concentration in stemflow, indicating that most species reacted in a similar way as H. physodes. Cover of L. conizaeoides increased with increasing SO⊂4⊂2- concentration, but decreased at higher SO⊂4⊃2- concentrations. Bark chemistry had a minor influence on lichen diversity.