We investigated the effect of long-term ingestion of dietary medium-chain triacylglycerols (MCT) on body weight and fat in humans. Using a double-blind, controlled protocol, we assessed the potential health benefits of MCT compared with long-chain triacylglycerols (LCT) in 78 healthy men and women [body mass index (BMI) > or = 23 kg/m(2): n = 26 (MCT), n = 30 (LCT); BMI < 23 kg/m(2): n = 15 (MCT), n = 7 (LCT)]. Changes in anthropometric variables, body weight and body fat during the 12-wk MCT treatment period were compared with those in subjects consuming the LCT diet. The subjects were asked to consume 9218 kJ/d and 60 g/d of total fat. The energy, fat, protein and carbohydrate intakes did not differ significantly between the groups. Body weight and body fat in both groups had decreased by wk 4, 8 and 12 of the study. However, in the subjects with BMI > or = 23 kg/m(2), the extent of the decrease in body weight was significantly greater in the MCT group than in the LCT group. In subjects with BMI > or = 23 kg/m(2), the loss of body fat in the MCT group (-3.86 +/- 0.3 kg) was significantly greater than that in the LCT group (-2.75 +/- 0.2 kg) at 8 wk. In addition, in subjects with BMI > or = 23 kg/m(2), the decrease in the area of subcutaneous fat in the MCT group was significantly greater than that in the LCT group at wk 4, 8 and 12. These results suggest that the MCT diet may reduce body weight and fat in individuals (BMI > or = 23 kg/m(2)) more than the LCT diet.

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We found previously that the ingestion of margarine containing medium-chain triacylglycerols (MCT) resulted in a significant increase in postprandial thermogenesis when compared with long-chain triacylglycerols (LCT). Diets that included margarine containing MCT and LCT were compared for 12 weeks in 73 subjects to investigate the effects on body weight, body fat, areas of subcutaneous and visceral fat, serum total cholesterols, triglycerides, lipoproteins, plasma glucose, serum insulin, total ketone bodies, and the activities of aspartate aminotransferase, alanine aminotransferase, and γ-glutamyltranspeptidase. We conducted a double-blind, controlled study and used blended rapeseed oil and soybean oil (LCT) as a comparison. Two groups ingested 2,100-2,400 kcal/day of energy, 65-73 g/day of total fat, and 14 g/day of test margarine (5 g/day of MCT or LCT). The subjects on the MCT diet demonstrated significant decreases in body fat weight (-3.8 ± 2.4 kg vs -2.4 ± 1.7 kg; MCT vs LCT, mean ± SD), subcutaneous fat (-38.2 ± 29.9 cm 2 vs -22.6 ± 19.3 cm 2 ), and visceral fat (-12.2 ± 11.2 cm 2 vs -1.6 ± 12.8 cm 2 ) after 12 weeks. There were no clinical differences in measured blood parameters. We suggest that the postprandial increase in thermogenesis and control of postprandial triglyceride levels may explain these results. J Atheroscler Thromb, 2003; 10: 290-298.

We examined whether extracellular signals regulate glycogen synthase kinase-3 (GSK-3) activity through tyrosine dephosphorylation of GSK-3. In resting Chinese hamster ovary cells overexpressing the human insulin receptor (CHO-IR cells), GSK-3 was tyrosine-phosphorylated and active. Insulin and 12-O-tetradecanoylphorbol 13-acetate (TPA) induced inactivation and tyrosine dephosphorylation of GSK-3. It is known that Ser-9 of GSK-313 is phosphorylated in response to insulin and that the phosphorylation of this amino acid residue causes inactivation of GSK-313. However, the ectopically expressed GSK-3I] a9, in which the N-terminal nine amino acids of GSK-313 were deleted, was still inactivated and tyrosine-dephosphorylated in response to insulin. Protein phosphatase 2A treatment partially reversed insulin-induced GSK-31~ inactivation, but did not change GSK-3~ A9 inactivation. In CHO-IR cells where protein kinase C was down-regulated, TPA neither inactivated nor tyrosine-dephosphorylated GSK-3. However, insulin inactivated and tyrosinedephosphorylated GSK-3, although to a lesser degree than in the control cells. These results suggest that in addition to serine phosphorylation, tyrosine dephosphorylation of GSK-3 is also important for the regulation of GSK-3 activity in response to extracellular signals and that insulin regulates GSK-3 activity through both protein kinase C-dependent as well as protein kiuase C-independent pathways.

Periodontal ligament tissue is remodeled on both the tension and compression sides of moving teeth during orthodontic tooth movement. The present study was designed to clarify the hypothesis that the expression of MMP-8 and MMP-13 mRNA is promoted during the remodeling of periodontal ligament tissue in orthodontic tooth movement. We used the in situ hybridization method and semi-quantitative reverse-transcription/polymerase chain-reaction analysis to elucidate the gene expression of MMP-8 and MMP-13 mRNA. Expression of MMP-8 and MMP-13 mRNA transiently increased on both the compression and tension sides during active tooth movement in vivo. The gene expression of MMP-8 and MMP-13 was induced by tension, while compression indirectly promoted the gene expression of MMP-8 and MMP-13 through soluble factors in vitro. Thus, we concluded that the expression of MMP-8 and MMP-13 is differentially regulated by tension and compression, and plays an important role in the remodeling of the periodontal ligament.