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- Berggren, A M, et al.
(författare)
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Influence of orally and rectally administered propionate on cholesterol and glucose metabolism in obese rats
- 1996
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Ingår i: British Journal of Nutrition. - 0007-1145. ; 76:2, s. 94-287
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Tidskriftsartikel (refereegranskat)abstract
- It has increasingly been suggested that the short-chain fatty acids (SCFA) acetic, propionic and butyric acids, derived from colonic fermentation of dietary fibre and other indigestible carbohydrates, exert different physiological effects. Formation of propionic acid is discussed in terms of beneficial effects on glucose and cholesterol metabolism. The aim of the present study was to evaluate possible metabolic effects of propionic acid and to differentiate between effects mediated in the upper gastrointestinal tract and those mediated in the hind-gut. For this purpose, obese hyperinsulinaemic (fa/fa) rats were studied during a 19 d test period. Sodium propionate was either fed orally through the diet (1 g/d), or infused rectally (0.15 g/d) to animals given diets high in cholesterol (20 g/kg) and saturated fat (130 g/kg). At the end of the test period total liver cholesterol pools were 20% lower (P < 0.01) in rats given dietary or rectally infused propionate (481 and 484 mg respectively) compared with the control group (614 mg). This was due to lower liver weights (P < 0.05) in propionate-treated animals, 15.5 and 15.3 g, v. 18.2 g in the control group, and no differences were noted in hepatic cholesterol concentrations. The urinary glucose excretion was measured during days 15-19 and was found to be lower (P < 0.05) in rats fed with propionate (23 mg) compared with the control group or the group infused rectally (39 and 38 mg respectively). In addition, fasting plasma glucose concentrations decreased significantly (P < 0.05) over the test period. It is concluded that orally supplied propionate affects both glucose and cholesterol metabolism as judged from lowered urinary glucose excretion, fasting blood glucose and liver cholesterol pools. On the other hand, propionate administered to the hind-gut at a physiologically relevant level reduces the hepatic cholesterol pool.
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- Barg, Sebastian, et al.
(författare)
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The stimulatory action of tolbutamide on Ca2+-dependent exocytosis in pancreatic beta cells is mediated by a 65-kDa mdr-like P-glycoprotein
- 1999
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Ingår i: Proceedings of the National Academy of Sciences. - : Proceedings of the National Academy of Sciences. - 1091-6490 .- 0027-8424. ; 96:10, s. 5539-5544
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Tidskriftsartikel (refereegranskat)abstract
- Intracellular application of the sulfonylurea tolbutamide during whole-cell patch-clamp recordings stimulated exocytosis >5-fold when applied at a cytoplasmic Ca2+ concentration of 0.17 microM. This effect was not detectable in the complete absence of cytoplasmic Ca2+ and when exocytosis was elicited by guanosine 5'-O-(3-thiotriphosphate) (GTPgammaS). The stimulatory action could be antagonized by the sulfonamide diazoxide, by the Cl--channel blocker 4,4'-diisothiocyanatostilbene-2,2'-disulfonic acid (DIDS), by intracellular application of the antibody JSB1 [originally raised against a 170-kDa multidrug resistance (mdr) protein], and by tamoxifen (an inhibitor of the mdr- and volume-regulated Cl- channels). Immunocytochemistry and Western blot analyses revealed that JSB1 recognizes a 65-kDa protein in the secretory granules. This protein exhibited no detectable binding of sulfonylureas and is distinct from the 140-kDa sulfonylurea high-affinity sulfonylurea receptors also present in the granules. We conclude that (i) tolbutamide stimulates Ca2+-dependent exocytosis secondary to its binding to a 140-kDa high-affinity sulfonylurea receptor in the secretory granules; and (ii) a granular 65-kDa mdr-like protein mediates the action. The processes thus initiated culminate in the activation of a granular Cl- conductance. We speculate that the activation of granular Cl- fluxes promotes exocytosis (possibly by providing the energy required for membrane fusion) by inducing water uptake and an increased intragranular hydrostatic pressure.
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- Berggren, Anna M., et al.
(författare)
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Short‐chain fatty acid content and pH in caecum of rats fed various sources of starch
- 1995
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Ingår i: Journal of the Science of Food and Agriculture. - : Wiley. - 0022-5142 .- 1097-0010. ; 68:2, s. 241-248
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Tidskriftsartikel (refereegranskat)abstract
- Caecal pH and contents of short‐chain fatty acids (SCFA) were registered in rats fed three potential sources of resistant starch (RS); raw pea starch, raw potato starch, and an RS‐enriched preparation obtained from wheat starch by autoclaving and enzymatic incubation. Small intestinal digestibility and delivery of RS to the hind‐gut in the case of raw starches were determined by analysis of faecal starch in animals treated with antibiotics to prevent hind‐gut fermentation. RS content in the RS‐enriched preparation was determined as total starch remaining in an enzymatic gravimetric dietary fibre residue. The fermentability of RS was estimated from the faecal recovery of starch in normal animals with intact hind‐gut microflora. Approximately 35 g per 100 g and 32 g per 100 g were RS in the case of raw potato starch and the RS‐enriched preparation, respectively, versus only 1 g per 100 g in the case of raw pea starch. The caecal pH decreased with all test diets, being most significant with raw potato starch. SCFA production and faecal bulking were negligible with raw pea starch, whereas both raw potato starch and the RS‐enriched preparation significantly increased these parameters. The fermentability of RS in raw potato starch and the RS‐enriched preparation was similar, or about 60–70%. If calculated on basis of fermented amount, RS in raw potato starch was more potent in generating SCFA (49 μmol g−1) than in the RS‐enriched preparation (19 μmol g−1). RS in raw potato starch also displayed the highest faecal bulking capacity. In fact, the faecal dry weight increased more than expected merely from delivery of RS. The relative proportion in caecal contents of acetic‐, propionic‐ and butyric acid was 70, 17 and 8%, respectively, with no significant differences between the three sources of RS.
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- Johansson, M L, et al.
(författare)
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Survival of Lactobacillus plantarum DSM 9843 (299v), and effect on the short-chain fatty acid content of faeces after ingestion of a rose-hip drink with fermented oats
- 1998
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Ingår i: International Journal of Food Microbiology. - 0168-1605. ; 42:1-2, s. 29-38
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Tidskriftsartikel (refereegranskat)abstract
- In a controlled and randomised double-blind study, 26 healthy adult volunteers consumed, for 21 d, 400 ml of a rose-hip drink containing oats (0.7 g/100ml) fermented with Lactobacillus plantarum DSM 9843 (RHL; containing 5 x 10(7) cfu ml(-1)), and 22 volunteers in a second group the same amount of a pure rose-hip drink (RH). Significant increases in the total faecal concentration of carboxylic acids (P < 0.05 after 1 week and P < 0.01 after 3 weeks of intake), acetic acid (P < 0.01 after 3 weeks of intake) and propionic acid (P < 0.01 after 3 weeks of intake and P < 0.05 eight days after intake ceased) were recorded in the RHL group, indicating increased fermentation in the colon. In both groups a significant increase was obtained in the concentration of faecal lactic acid (P < 0.001 after 1 and 3 weeks of intake). No changes were seen in the concentration of faecal butyrate. The numbers of faecal bifidobacteria and lactobacilli increased significantly in both groups after 3 weeks of intake. Sulphite-reducing clostridia rapidly decreased in the group receiving the product with Lb. plantarum DSM 9843 after 1 week of intake, and then also in the pure rose-hip group after 3 weeks of intake. No changes were seen in the numbers of total anaerobes, gram-negative anaerobes or total aerobes during administration. Lb. plantarum DSM 9843 was recovered in faeces from all volunteers in the RHL group. Median amounts were 7.0 (5.0-8.8) log10 cfu g(-1) after one week of intake, and 6.7 (5.0-8.9) log10 cfu g(-1) after 3 weeks, respectively. The strain was still recovered from faeces of five volunteers 8 d after administration ceased (> 4.8 log10 cfu g(-1)). During the period of intake the volunteers in the RHL group experienced a significant increase in stool volume, a significant decrease in flatulence and slightly softer stools. Volunteers in the RH group experienced a slight but significant decrease in stool volume.
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- Ostrick, J. R., et al.
(författare)
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Conductivity-type anisotropy in molecular solids
- 1997
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Ingår i: Journal of Applied Physics. - : American Institute of Physics (AIP). - 0021-8979 .- 1089-7550. ; 81:10, s. 6804-6808
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Tidskriftsartikel (refereegranskat)abstract
- Thin polycrystalline films of perylenetetracarboxylic dianyhydride (PTCDA), an organic molecular solid, exhibits substantial anisotropies in its electronic transport properties. Only electrons transport in the directions along molecular planes, while mainly holes transport in the direction normal to molecular planes. A series of measurements on both field effect transistors with PTCDA active layers and light emitting diodes with PTCDA transport layers documents the anisotropy seen in the electronic transport in thin films of PTCDA. (C) 1997 American Institute of Physics.
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