Clinical aspects of coliform mastitis in the bovine

In 1979, 209 cows from 2742 patients in the clinic for obstetrics and gynecology suffered from coliform mastitis. Most of these animals had been sent to the clinic because of a general or local infectious disease, a delayed birth or a teat injury. Coliform mastitis developed secondarily. Only 12 animals (6%) had solely a mastitis and no other clinically recognisable disease. Most of them showed a secondary acetonemia (ketosis). The connection between hypoglycemia, disturbance of the body's own defense mechanism and development of a coliform mastitis is discussed. The frequent occurrence of coliform mastitis in dairy herds with sawdust bedding is not directly attributed to a coliform contamination of the bedding but indirectly to a lack of crude fibre content in the diet which results in a subclinical ketosis and a dysfunction of the leucocytic defense. Coliform mastitis predominantly is not a hygienic but a management problem.     

Structure-activity relationships of triazinone herbicides on resistant weeds and resistant Chlamydomonas reinhardtii

Weeds resistant to the s-triazine herbicide atrazine also show resistance to the triazinone herbicide metribuzin. However, with highly lipophilic triazinones, thylakoids isolated from atrazine-resistant Amaranthus retroflexus (mutation at position Ser₂₆₄ of the photosystem II D-1 reaction centre protein) in general show a higher pI₅₀ value in photosystem II electron transport than those from the wild type (i.e. negative cross-resistance; ‘supersensitivity’). A quantitative structure–activity relationship (QSAR) can be established, wherein the lipophilicity of the compound plays a major role. In in-vivo experiments, it was found that the triazinone DRW2698 killed resistant Amaranthus retroflexus and Chenopodium album whereas the wild type was almost unaffected. Triazinones were further investigated in five different mutants of Chlamydomonas rheinhardtii (mutations in the D-1 protein at positions Ser₂₆₄, Ala₂₅₁, Leu₂₇₅, Phe₂₅₅, and Val²¹⁹). Inhibitory activity of all triazinones was generally enhanced in the Phe₂₅₅ mutant but decreased in the Val₂₁₉ mutant. In the other mutants, biological activity was decreased when position 3 of the triazinone was substituted by CH₃, OCH₃, SCH₃, NHCH₃ or N(CH₃)₂. However, negative cross-resistance was again observed when this position was occupied by free thiol. It is therefore suggested that these two groups of triazinones orient themselves differently within the herbicide binding niche of the photosystem II D-1 protein.     

Effect of pyrethroids on carbohydrate metabolic pathways in common carp,Cyprinus carpio

The activity levels of succinate dehydrogenase (SDH) and glucose‐6‐phosphate dehydrogenase (G6PD) were assessed in various tissues of Cyprinus carpio var communis which had been exposed to lethal concentrations of group‐II pyrethroids (deltamethrin, cypermethrin, fenvalerate and fluvalinate) for a period of 72 h. The results indicated a steady decrease in SDH activity with a concomitant increase in G6PD activity. The decreased SDH activity indicated inhibition of SDH at mitochondrial level and the increased G6PD activity an enhancement of an alternative pathway of carbohydrate metabolism, viz the hexose monophosphate shunt (HMP) or pentose phosphate pathway as a biochemical adaptation to overcome the toxic stress. © 2001 Society of Chemical Industry