| 1. |
- Wikström, Jakob D., et al.
(författare)
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Hormone-induced mitochondrial fission is utilized by brown adipocytes as an amplification pathway for energy expenditure
- 2014
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Ingår i: EMBO Journal. - : Wiley. - 0261-4189 .- 1460-2075. ; 33:5, s. 418-436
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Tidskriftsartikel (refereegranskat)abstract
- Adrenergic stimulation of brown adipocytes (BA) induces mitochondrial uncoupling, thereby increasing energy expenditure by shifting nutrient oxidation towards thermogenesis. Here we describe that mitochondrial dynamics is a physiological regulator of adrenergically-induced changes in energy expenditure. The sympathetic neurotransmitter Norepinephrine (NE) induced complete and rapid mitochondrial fragmentation in BA, characterized by Drp1 phosphorylation and Opa1 cleavage. Mechanistically, NE-mediated Drp1 phosphorylation was dependent on Protein Kinase-A (PKA) activity, whereas Opa1 cleavage required mitochondrial depolarization mediated by FFAs released as a result of lipolysis. This change in mitochondrial architecture was observed both in primary cultures and brown adipose tissue from cold-exposed mice. Mitochondrial uncoupling induced by NE in brown adipocytes was reduced by inhibition of mitochondrial fission through transient Drp1 DN overexpression. Furthermore, forced mitochondrial fragmentation in BA through Mfn2 knock down increased the capacity of exogenous FFAs to increase energy expenditure. These results suggest that, in addition to its ability to stimulate lipolysis, NE induces energy expenditure in BA by promoting mitochondrial fragmentation. Together these data reveal that adrenergically-induced changes to mitochondrial dynamics are required for BA thermogenic activation and for the control of energy expenditure.
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| 2. |
- Bornman, Riana, et al.
(författare)
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DDT in Brest Milk: Intake, Risk, Lactation Duration, and Effect of Gender.
- 2012
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Ingår i: Epidemiology. - : Ovid Technologies (Wolters Kluwer Health). - 1044-3983.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- DDT is annually applied indoors of every dwelling at 64-128 g DDT for malaria vector control. We studied 163 breast milk samples from three DDT-sprayed villages and one reference village in South Africa for the presence and levels of DDT. Mean ?DDT levels in breast milk from the DDT-sprayed villages were 18, 11, and 9.5 mg/kg mf (milk fat) (1.4 mg/kg mf reference village). Primipara mothers from DDT-sprayed villages had significantly higher levels ?DDT in their milk. The highest DDT level in breast milk ever reported from South Africa was detected (5.2 mg/l wm (whole milk) and 140 mg/kg mf). The Maximum Residue Limit (MRL) in milk and Provisional Tolerable Daily Intake (PTDI) for DDT by infants were significantly exceeded in DDT-sprayed villages (maximum exceeded the MRL 310 times, and the PTDI 99 times). The differences between villages indicated differences in exposure and uptake due to application, substrate, and/or culture. The duration of completed lactation was similar for all four villages and DDT exposure had no effect on the duration. There were indications (not significant) that first-born female infants drank milk with higher ?DDT levels than first-born male infants and vice versa for multipara male and female infants. These patterns were evident in each of the DDT-spayed villages, suggesting gender involvement on levels of DDT in breast milk. In view of the high levels recorded, effective measures to reduce DDT exposure are urgently needed, over and above the need to find suitable, safe, and sustainable alternatives.
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| 3. |
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| 4. |
- Bouwman, Hindrik, et al.
(författare)
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High levels of DDT in breast milk: Intake, risk, lactation duration, and involvement of gender
- 2012
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Ingår i: Environmental Pollution. - : Elsevier. - 0269-7491 .- 1873-6424. ; 170, s. 63-70
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Tidskriftsartikel (refereegranskat)abstract
- We investigated presence and levels of DDT in 163 breast milk samples from four South African villages where, in three of them, malaria is controlled with DDT-sprayed indoors. Mean Sigma DDT levels in breast milk were 18, 11, and 9.5 mg/kg mf (milk fat) from the three DDT-sprayed villages, respectively, including the highest Sigma DDT level ever reported for breast milk from South Africa (140 mg/kg mf). Understanding the causes for these differences would be informative for exposure reduction intervention. The Provisional Tolerable Daily Intake (PTDI) for DDT by infants, and the Maximum Residue Limit (MRL) were significantly exceeded. DDT had no effect on duration of lactation. There were indications (not significant) from DDT-sprayed villages that first-born female infants drink milk with more Sigma DDT than first-born male infants, and vice versa for multipara male and female infants, suggesting gender involvement on levels of DDT in breast milk - requiring further investigation.
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