| 1. |
- Celander, Malin C., 1962, et al.
(författare)
-
DEVELOPMENT OF ALTERNATIVE MATHEMATICAL TOOLS TO ASSESS SYNERGISTIC MIXTURE EFFECTS
- 2015
-
Ingår i: 18th International symposium on Pollutant Responses in Marine Organisms (PRIMO18).
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Mixture effects are well known problems but chemical legislations are typically based on single chemical toxicity, which is unfortunate as chemicals occur as mixtures in the environment. There are mathematical models to assess additive mixture effects that are based on linear mixture effects such as toxicodynamic interactions. Chemicals with same or different mode-of-actions can also interfere with each other’s elimination pathways that can result in toxicokinetic interactions and cause indirect mixture effects. Therefore, chemicals that inhibit CYP enzymes in the elimination pathways of different classes of environmental pollutants can cause non-linear mixture effects that are more-than-additive. More-than-additive mixture effects have been observed between azoles and other classes of environmental pollutants such as estrogenic chemicals and aromatic hydrocarbons, as a result of toxicokinetic interactions via CYP1A/CYP3A inhibitions. There is need for new mathematical models to assess non-linear mixture effects. We have initiated the development of alternative mathematical tools to forecast non-linear mixture effects that are based on toxicokinetic interactions from earlier lab-studies in fish and fish cells. Time-dynamic is a key factor in toxicokinetic interactions and therefore we will combine multiple differential equations in the models. These equations describe how one chemical’s concentration changes over time in relationship to changes of another chemical’s concentration over time and how that affect biomarker responses such as CYP1A and vitellogenin. We will use statistical tools to quantitatively fit the suggested models with data from lab-studies. Non-linear models can be used to describe synergistic mixture effects. Those could be bottom-up-models, where we start from the different chemicals involved, or they could be top-down-models, where we fit a multi-dimension function to a given dataset using an auxiliary non-linear model. Our preliminary non-linear mathematical top-down model describes how the vitellogenin and the CYP1A biomarker responses can vary with concentrations of a synthetic estrogen and an antimycotic azole.
|
|
| 2. |
- Clemensson Lindell, Ida, et al.
(författare)
-
Adenosine triphosphate bioluminescence for hygiene testing of rubber liners and tubes on dairy farms
- 2018
-
Ingår i: Journal of Dairy Science. - : American Dairy Science Association. - 0022-0302 .- 1525-3198. ; 101, s. 2438-2447
-
Tidskriftsartikel (refereegranskat)abstract
- Prevention of biofilm formation in milking equipment is important to ensure good hygiene quality of raw milk. Key factors to achieving good results are a successful cleaning procedure and a method to check the cleanliness of milking equipment surfaces. Adenosine triphosphate bioluminescence is a fast and easy method for investigating bacterial contamination of surfaces. However, previous studies on the potential of ATP bioluminescence to assess the hygiene status of milking equipment have been hampered by lack of a validated test procedure. The aim of this work was therefore to establish a test procedure for assessing the cleanliness of milking equipment using ATP bioluminescence, and apply the method on-farm to study the hygiene status of aging rubber material in milking equipment. In developing the test procedure, the effects of sampling location in tubes and liners, sampling of dry versus wet barrels, milking point in the parlor, and acid or alkali detergent on ATP values were investigated. The results showed that, to obtain reproducible results, replicate sampling from the same milking points in the parlor is important. For milk tubes, samples should preferably be taken from the milk meter side, for liners on the inside of the barrel. For best results, sampling should be performed after use of alkali detergent. No beneficial effect was observed of sampling dry liner barrels, so sampling in the standardized test procedure is performed directly after cleaning. The standardized test procedure was used on 3 different commercial farms and sampling was initiated after replacement of old rubber parts. On one of the farms, additional sampling was performed to evaluate total bacteria count and determine the association with ATP level. The results suggest that, provided an efficient cleaning procedure is used, the hygiene quality of milking equipment can be maintained during the recommended lifetime of the rubberware. However, due to occasional variation in cleaning efficiency between milking points and liner barrels, random sampling on single occasions can lead to incorrect conclusions. Replicate sampling over time is therefore important for correct interpretation of ATP bioluminescence data. If ATP levels are very high, complementary sampling for total bacteria count should be used to verify that the level is due to bacterial contamination, and not other organic ATP-contributing material (e.g., milk residues).
|
|
| 3. |
- Johansson, Monika, et al.
(författare)
-
Composition and enzymatic activity in bulk milk from dairy farms with conventional or robotic milking systems
- 2017
-
Ingår i: Journal of Dairy Research. - 0022-0299 .- 1469-7629. ; 84, s. 154-158
-
Tidskriftsartikel (refereegranskat)abstract
- The objective of the studies reported in this research communication was to investigate differences in composition and enzymatic activities in bulk milk samples provided from Swedish dairy farms with different management systems, i.e. automated (AMS) and conventional milking systems (CMS). A bulk milk sample was collected from each of 104 dairy farms, 51 using AMS and 53 using CMS, located in the same geographical region. Sampling took place within two consecutive days during the indoor period (October). Milk samples were analysed for contents of total fat and protein, free fatty acids (FFA), caseins and whey proteins, somatic cell count (SCC), pH, plasmin and plasminogen derived activities, and total proteolysis. Our results showed a lower protein content and higher SCC in bulk milk from AMS herds compared with milk from CMS herds. Plasmin, plasminogen and total plasmin/plasminogen derived activities were lower in milk from AMS herds but despite this, total casein and the beta-casein fraction as % of total protein were lower in milk from AMS herds than in milk from herds using CMS. Total proteolysis was higher in milk from AMS herds, suggesting that other proteases than plasmin, e.g. cellular and bacterial proteases, contributed to the degradation of casein. This was supported by a positive correlation between SCC and total proteolysis (P < 0.01), as well as a negative correlation between total proteolysis and beta-casein fraction (P < 0.05). In conclusion, comparing the quality of bulk milk from commercial dairy herds using AMS and CMS, respectively, several differences were observed, suggesting a significant effect from management system.
|
|
| 4. |
|
|
| 5. |
|
|
