Detection of a promoter polymorphism in the gene of intestinal fatty acid binding protein (I-FABP).

Postprandial fat absorption is supposed to be a major factor in the development of the metabolic syndrome. In recent years, the assimilation of plasma triglycerides has been the focus of several groups, revealing a number of specific fat or fatty acid transporters. The intestinal fatty acid binding protein, I-FABP-2, participates in the absorption of nutritional fats. The influence of a coding polymorphism has been investigated intensively. However, it remains still unclear whether this polymorphism has a major impact on postprandial TG levels in humans. We found a polymorphism in the promoter of FABP-2, which might involve the retinoid receptor in the transcriptional activity. In functional analysis, we have been able to demonstrate that the various promoter alleles develop different activities in the human intestinal epithelial cells and that the postprandial appearance of plasma TGs in healthy subjects also depends on their genotype. Since the distribution of the identified promoter polymorphism does not differ in subjects suffering from type 2 diabetes, the overall influence on the development of the metabolic syndrome seems to be minor.

Treatment of dyslipoproteinemia in the metabolic syndrome.

The metabolic syndrome consists of a cluster of metabolic disorders, many of which promote the development of atherosclerosis and increase the risk to develop cardiovascular disease. The metabolic syndrome is characterized by atherogenic dyslipidemia (elevated triglycerides, increased small dense low-density lipoproteins, and decreased high-density lipoproteins), hypertension, insulin resistance and obesity. To decrease the risk of cardiovascular disease events decreasing body weight by ingesting a healthy diet, increasing physical activity, cessation of smoking and managing dyslipidemia are recommended. Pharmacological treatment of dyslipidemia is based on different drug classes. For LDL-cholesterol-lowering mainly statins and for triglyceride-lowering mainly fibrates are used. In primary and secondary prevention trials of heart disease they have shown to reduce the incidence of coronary artery disease or coronary events by 25-60 percent. Statins reduce mainly LDL-cholesterol levels by competitive inhibition of HMG-CoA reductase but have also shown to reduce fasting and postprandial triglyceride levels. Fibrates effectively reduce fasting and postprandial lipemia, shift the distribution of LDL particles towards less dense particles and increase HDL-cholesterol. Thus fibrates particularly address components of the metabolic syndrome and features of diabetic dyslipidemia. However studies still are needed showing definite evidence on differential therapy in lipid lowering based on prospective controlled trials with endpoints of macro- and microangiopathy in diabetic patients.

Probiotics--compensation for lactase insufficiency.

Yogurt and other conventional starter cultures and probiotic bacteria in fermented and unfermented milk products improve lactose digestion and eliminate symptoms of intolerance in lactose maldigesters. These beneficial effects are due to microbial beta-galactosidase in the (fermented) milk product, delayed gastrointestinal transit, positive effects on intestinal functions and colonic microflora, and reduced sensitivity to symptoms. Intact bacterial cell walls, which act as a mechanical protection of lactase during gastric transit, and the release of the enzyme into the small intestine are determinants of efficiency. There is a poor correlation between lactose maldigestion and intolerance; in some studies, low hydrogen exhalation without significant improvement of clinical symptoms was observed. Probiotic bacteria, which by definition target the colon, normally promote lactose digestion in the small intestine less efficiently than do yogurt cultures. They may, however, alleviate clinical symptoms brought about by undigested lactose or other reasons.

Differential effects of saturated and monounsaturated fatty acids on postprandial lipemia and incretin responses in healthy subjects.

BACKGROUND: Elevations of postprandial triacylglycerol-rich plasma lipoproteins and suppressions of HDL-cholesterol concentrations are considered potentially atherogenic. Long-term studies have shown beneficial effects of monounsaturated fatty acids (eg, oleic acid) on fasting lipid and lipoprotein concentrations in humans. A direct stimulatory effect of oleic acid on the secretion of glucagon-like peptide 1 (GLP-1) was shown in animal studies. OBJECTIVE: We compared the postprandial responses of glucose, insulin, fatty acids, triacylglycerol, gastric inhibitory polypeptide (GIP), and GLP-1 to test meals rich in saturated and monounsaturated fatty acids. DESIGN: Ten young, lean, healthy persons ingested 3 meals: an energy-free soup consumed with 50 g carbohydrate (control meal), the control meal plus 100 g butter, and the control meal plus 80 g olive oil. Triacylglycerol and retinyl palmitate responses were measured in total plasma, in a chylomicron-rich fraction, and in a chylomicron-poor fraction. RESULTS: No significant differences in glucose, insulin, or fatty acid responses to the 2 fat-rich meals were seen. Plasma triacylglycerol responses were highest after the butter meal, with chylomicron triacylglycerol rising 2.5-5-fold. Retinyl palmitate responses were higher and more prolonged after the butter meal than after the control and olive oil meals, whereas both postprandial HDL-cholesterol concentrations and GLP-1 and GIP responses were higher after the olive oil meal than after the butter meal. CONCLUSIONS: Olive oil induced lower triacylglycerol concentrations and higher HDL-cholesterol concentrations than butter, without eliciting differences in concentrations of glucose, insulin, or fatty acids. Furthermore, olive oil induced higher concentrations of GLP-1 and GIP than did butter, which may point to a relation between fatty acid composition, incretin responses, and triacylglycerol metabolism in the postprandial phase.

Chylomicrons induce E-selectin and VCAM-1 expression in endothelial cells.

An increased adherence of leukocytes to the vascular endothelium appears to be a crucial event in the development of atherosclerosis. The role of endothelial cell adhesion molecules is gaining increasingly interest in this context. Several studies show an influence of lipoproteins, especially low-density-lipoproteins on adhesion molecule stimulation. The aim of our study was to analyze the atherogenic potential of postprandially elevated serum triglyceride levels by investigating the impact of postprandial lipoproteins (chylomicrons (CH, isolated 4 h after a standard oral lipid load)) on the expression of E-selectin (endothelial leukocyte adhesion molecule-1, ELAM-1) and VCAM-1 (vascular cell adhesion molecule-1). In addition we used chylomicrons that had been incubated with lipoprotein lipase (50 U/ml) for 3 h (CH-LPL). The endotoxin lipopolysaccharide (LPS) served as positive control for adhesion molecule stimulation. Human umbilical vein endothelial cells (HUVEC) were incubated with the samples for 4 h and expression of E-Selectin and VCAM-1 was determined by ELISA. The expression of E-selectin was induced by LPS (530 +/- 64% compared to the basal activity (= 100%)) and by CH (342 +/- 94%); CH-LPL had no effect on E-Selectin expression. VCAM-1 expression was stimulated by LPS (395 +/- 221%) and similarly by CH-LPL (322 +/- 136%) but considerably stronger by CH (1245 +/- 324). In summary, chylomicrons induced an enhancement of the expression of both adhesion molecules, which closely resembled or even exceeded the endotoxin-induced stimulation. Interestingly, this effect was diminished or even reversed after incubation with LPL.

Sequence and expression analysis of the hrpB pathogenicity operon of Xanthomonas campestris pv. vesicatoria which encodes eight proteins with similarity to components of the Hrp, Ysc, Spa, and Fli secretion systems.

In this paper we describe the molecular characterization of hrpB, the largest operon in the Xanthomonas campestris pv. vesicatoria hrp cluster. The hrpB region encompasses 6 kb and encodes eight putative proteins, seven of which were expressed in Escherichia coli. The HrpB3 protein is the only one carrying a signal peptide sequence at the N-terminus and is a putative lipoprotein localized in the outer membrane of X. campestris pv. vesicatoria. The HrpB4 and HrpB8 proteins contain one and five putative transmembrane domains, respectively, and are most likely associated with the inner membrane. The HrpB3, HrpB5, HrpB6, and HrpB8 proteins show sequence similarity to putative components of different type III protein secretion pathways in bacteria. Examples include Hrp proteins from other plant pathogens, YscJ, YscN, YscL, and YscT of Yersinia spp., and MxiJ, Spa47, adn Spa29 of Shigella flexneri. The transcription start site and the hrpB promoter was identified. The minimal hrpB promoter region of 90 bp contains a novel sequence motif, the PIP-box, which might play a role in transcription activation of the hrpB operon and possibly other plant-induced genes of X. campestris pv. vesicatoria.

The phenomenon of a high triglyceride response to an oral lipid load in healthy subjects and its link to the metabolic syndrome.

Excessive postprandial triglyceride (TG) responses despite normal fasting TG levels have been described in single cases within small groups of healthy subjects and in patients with obesity or precocious atherosclerosis, known to be associated with high insulin fasting levels. To clarify this association, fasting and postprandial TG and insulin levels were studied in 113 healthy young (25.7 +/- 2.6 years), normal weight (body mass index 20.8 +/- 2.3 kg/m2) male subjects who were selected from among 117 subjects on the basis of TG fasting levels < 200 mg/dl. After a 12-hour fast a standardized liquid lipid load was administered containing 58 g mainly saturated fat and 1,017 kcal energy. Both fasting TG values and postprandial TG peak values showed bimodal frequency distributions. Statistical analysis of fasting TG discriminated two groups: a low fasting TG group with normally distributed values < 150 mg/dl (mean +/- SEM: 79.5 +/- 2.7 mg/dl; n = 104) and a high fasting TG group > 150 mg/dl (194.5 +/- 7.2 mg/dl; n = 13). Likewise, two groups could be differentiated according to their maximal postprandial TG response (TG max) to the lipid load: (1) normal responders with TG max < 260 mg/dl (mean +/- SEM: 123 +/- 4.8 mg/dl; n = 96) and (2) high responders with TG max > 260 mg/dl (272.5 +/- 20.5 mg/dl; n = 17). Fasting TG and TG max were highly correlated (r = 0.745; p < 0.0001). However, 9 of 17 (53%) high responders had fasting TG < 150 mg/dl, which means that the prediction of high response is only 47.0% based on fasting TG values. Fasting insulin levels were significantly higher in high responders than in normal responders, whereas they did not differ between the low and high fasting TG group. In conclusion, the bimodal frequency distribution of TG max after a lipid load permitted the differentiation of two groups, normal responders and high responders, with higher fasting insulin levels, which might indicate a link to the metabolic syndrome.

Determinants of pathogenicity in Xanthomonas campestris pv. vesicatoria are related to proteins involved in secretion in bacterial pathogens of animals.

One of the model systems investigated for studying plant bacterial pathogenesis is Xanthomonas campestris pv vesicatoria, the causal agent of bacterial spot disease of pepper and tomato. Genes necessary for both basic pathogenicity and the induction of the hypersensitive response in resistant plants (hrp genes) were previously isolated from X. c. pv. vesicatoria and characterized genetically. As a first step toward functional analysis, part of the hrp gene cluster, making up several loci, was sequenced. Here, we report the first indications of the function of hrp genes. Striking similarities to proteins from the mammalian pathogens Shigella flexneri, Yersinia enterocolitica, Y. pestis, and other bacteria were discovered. Proteins encoded by genes within the X. c. pv. vesicatoria loci hrpA, hrpB, and hrpC are similar to ATPases and to Yersinia Ysc and LcrD proteins, which are involved in secretion of Yop proteins, a particular class of essential pathogenicity factors produced by Yersinia species. This finding indicates, for the first time, that the fundamental determinants of pathogenicity may be conserved among bacterial pathogens of plants and animals. We hypothesize that hrp genes are involved in the secretion of molecules essential for the interaction of X. c. pv. vesicatoria with the plant.