Biomedical subjects

Nathalie Delzenne

Publications and source records attributed to Nathalie Delzenne.

5 recordsLinked to original sources

PubMed2004

PASSCLAIM--body weight regulation, insulin sensitivity and diabetes risk.

BACKGROUND: Insulin sensitivity is a key function in human metabolism because it has a crucial role in the development of disease that are increasingly common in modern society. Impaired insulin sensitivity is an important determinant of type 2 diabetes; moreover, it has been proposed as an independent risk factor for cardiovascular disease. Thus, reduced insulin sensitivity is strongly associated with the metabolic syndrome, which represents a cluster of metabolic abnormalities and cardiovascular risk factor. Insulin sensitivity can be modulated by different environmental factors, including dietary habits. Obesity, especially if associated with abdominal adiposity, impairs insulin-sensitivity while physical activity can improve it; however, the composition of the habitual diet is clearly an important regulator of this function. AIM: To evaluate methodologies and markers that can be used to substantiate existing and potential claims of beneficial effects of foods on relevant functions connected with body fat deposition, insulin sensitivity and blood glucose regulation. RESULTS: We have reviewed the scientific basis for existing and potential claims, based not only on modifications of the target functions (body fat deposition, insulin sensitivity and blood glucose regulation) but also on modifications of other relevant associated functions (energy intake, energy expenditure, fat storage and oxidation, lipotoxicity, body fat composition, inflammation, oxidative stress, vascular function, glucose production and utilization). In this context we have identified a number of markers and evaluated appropriate method to measure and validate them. CONCLUSIONS: Relevant functions contributing to overweight, the metabolic syndrome and diabetes have been identified. The evidence reviewed indicates that in this field the link between nutrition, biological responses and diseases is clearly established. Therefore, there is a strong potential to develop functional food science. The major gap in the evidence continues to be the lack of diet based intervention trials of sufficient duration to be relevant for affecting the natural history of these conditions.

Absorptiometry, Photon↗

PubMed2003

Prebiotics: actual and potential effects in inflammatory and malignant colonic diseases.

PURPOSE OF REVIEW: This paper will summarize the most recent clinical and experimental data on the effects of prebiotics in inflammatory and cancerous diseases of the large intestine. RECENT FINDINGS: Animal studies, as well as data obtained in in-vitro cell culture systems, have underlined the potential of certain prebiotics to protect against inflammatory and cancerous processes in the large intestine. Clinical trials are now in progress to assess the relevance of these promising results. The biochemical mechanisms are still incompletely deciphered, but both the promotion of lactic acid-producing bacteria and the production of short-chain fatty acids, particularly butyrate, during the fermentation of prebiotics could be key factors. SUMMARY: Enteric resident bacteria are involved in inflammatory bowel diseases and may contribute to colonic carcinogenesis. Dietary manipulation of the flora may thus represent a useful aid to prevent or to treat these diseases, and this could be a place for prebiotics. Inulin-like prebiotics have shown encouraging results in animal models, but clinical and epidemiological trials are necessary to define their efficacy in humans. In the next few years, important advances are expected in understanding the interactions between prebiotics, intestinal flora and the colonic mucosa in health and diseases, enabling the improvement of therapy as well as better nutritional handling of susceptible individuals.

Animals↗

PubMed2003

Cryopreservation of rat precision-cut liver slices is associated with major metabolic stress and ionic perturbations.

BACKGROUND/AIMS: Cryopreserved precision-cut liver slices (PCLS) in culture exhibit a rapid decline in ATP level and anabolic processes by unknown mechanisms. The aim of this study is to elucidate the key events explaining the alterations occurring in cryopreserved PCLS. METHODS: Glucose metabolism, mitochondrial activities, ionic homeostasis and caspase-3 activity were assessed in fresh or cryopreserved (rapid freezing-thawing conditions) rat PCLS within the first hour of incubation in Williams' medium E at 37 degrees C. RESULTS: Despite a similar glycolytic activity under both conditions, only fresh PCLS were able to gradually recover their ATP and potassium content. Glycogen content dropped more rapidly in cryopreserved than in control PCLS. Only cryopreserved PCLS exhibited a decline in O2 consumption and a lower ATP/ADP ratio from 30 min of incubation with a loss of coupling of oxygen consumption to ATP synthesis and mitochondrial calcium transport after 1 hour of incubation. Caspase-3 activation was already present in cryopreserved PCLS after a few minutes of incubation. CONCLUSIONS: The lack of restoration of potassium/sodium exchange might be a primary event in the metabolic alterations occurring in cryopreserved PCLS after thawing, that contributes to further mitochondrial alterations, caspase activation and compromises ATP-dependent anabolic pathways.

Animals↗

PubMed2002

Insulin increases the sensitivity of tumors to irradiation: involvement of an increase in tumor oxygenation mediated by a nitric oxide-dependent decrease of the tumor cells oxygen consumption.

The effects of insulin on tumor oxygenation, perfusion, oxygen consumption,and radiation sensitivity were studied on two different mouse tumor models (TLT, a liver tumor, and FSAII, a fibrosarcoma). Anesthetized mice were infused with insulin i.v. at a rate of 16 milliUnits/kg/min for 25 min. Local tumor oxygenation measurements were carried out using two independent techniques: electron paramagnetic resonance oximetry and a fiber-optic device (OxyLite). Two complementary techniques were also used to assess the blood flow inside the tumor: a laser Doppler system (OxyFlo) and contrast-enhanced magnetic resonance imaging. The oxygen consumption rate of tumor cells after in vivo insulin infusion was measured using high frequency electron paramagnetic resonance oximetry. To know if insulin was able to enhance radiation-induced tumor regrowth delay, tumor-bearing mice were treated with 16 Gy of 250 kV radiation dose after insulin infusion. We provide evidence that insulin increases the local pressure of oxygen of tumors (from 0-3 mm Hg to 8-11 mm Hg) as well as the tumor response to irradiation (increasing regrowth delay by a factor of 2.11). We found that the insulin-induced increase of tumor pressure of oxygen: (a) is not caused by an increase in the tumor blood flow, which is even decreased after insulin infusion; (b) is because of a decrease in the tumor cell oxygen consumption (in vivo insulin consumed oxygen three times slower than control cells); and (c) is inhibited by a nitric oxide (NO) synthase inhibitor, Nomega-nitro-L-arginine methyl ester, when injected i.p. at 15 micromol/kg(-1), 1 h before insulin infusion. We demonstrate by immunoblotting that the NO pathway involves a phosphorylation of endothelial NO synthase and showed a concomitant increase in the cyclic GMP tumor level. These findings provide unique insights into biological processes in tumors, new possible management for treating cancer patients, and raise major questions about the role of insulin secretion (fasting status and diabetes) in the clinical response of tumors to radiation therapy.

Animals↗

PubMed2002

Dietary fructans, but not cellulose, decrease triglyceride accumulation in the liver of obese Zucker fa/fa rats.

This study was designed to compare the effects of dietary supplementation with nondigestible carbohydrates, differing in fermentability by colonic bacteria, on hepatic steatosis in growing obese Zucker rats. Male Zucker fa/fa rats were divided into three groups: a control group that received the basal diet, a fructan group that received 10 g highly fermented Synergy 1/100 g diet and a cellulose group that received 10 g poorly fermented Vivapur Microcrystalline cellulose/100 g diet. Rats consuming fructan had a lower energy intake, a lower body weight and less triacylglycerol accumulation in the liver as assessed in vivo by nuclear magnetic resonance (NMR) spectroscopy, and ex vivo by biochemical and histochemical analysis compared with the control and/or cellulose groups. The high fermentation of fructans compared with cellulose was reflected by greater cecal contents and by a twofold greater propionate concentration in the portal vein of rats fed fructan compared with those fed cellulose. By measuring the capacity of hepatocytes isolated from liver of Zucker rats to synthesize triglycerides or total lipids from different precursors, we showed that propionate, at the concentrations measured in the portal vein of rats treated with fructan, selectively decreased the incorporation of acetate into total lipids, a phenomenon that could contribute, along with the lower energy intake, to less triglyceride accumulation in the liver of obese Zucker rats fed dietary fructans.

Animals↗