Epidemiology of the metabolic syndrome in 2045 French military personnel (EPIMIL study)

CONTEXT

The Metabolic syndrome is considered to be an important public health problem, but few epidemiological studies have defined the present situation in France. EPIMIL is a prospective epidemiological study that began on February 1, 2003.

SUBJECTS AND METHODS

This study was designed to identify the clinical and laboratory parameters of metabolic syndrome and cardiovascular risk factors in a population of 2045 male military personnel based in the Paris region. The initial 1-year cross-sectional study will be followed by a 10-year follow-up and patient care.

RESULTS

The 2045 subjects included 185 (9%) presented at least 3 of the 5 NCEP ATP III criteria defining metabolic syndrome. They were significantly older (42.2 +/- 8.5 yrs) than the other subjects (37.3 +/- 8.7 yrs, P<0.001), had a higher BMI (29.5 +/- 3.4 vs 24.8 +/- 2.9 kg/m2, P<0.001) and a greater body weight at age 20 (75.4 +/- 11 vs 70.4 +/- 8.5 kg, P<0.01). Smoking, little physical activity and family histories of diabetes and arterial hypertension were more frequent in these men. While levels of the cholesterol and CRP us were higher, Lp(a) and homocysteine concentrations were normal. Plasma insulin and BMI (r = 0.456 P<0.0001) and plasma insulin and waist circumference (r = 0.446 P<0.0001) were well correlated. Lastly, plasma insulin, free fatty acids and cardiovascular risk increased steadily with the increase in the number of metabolic syndrome criteria.

CONCLUSIONS

These results in a large and particularly uniform population of men show the prevalence of metabolic syndrome in adult men, and demonstrate its link with insulin resistance. Men with several risk factors require specific care, particularly for hypertension and dyslipidemia; the effectiveness of this care will be evaluated during the follow-up period.

Chromatin texture analysis in living cells

In recent years, there has been an increasing interest in applications of fluorescence measurements to studies on many physiological mechanisms in living cells. However, few studies have taken advantage of DNA quantification by fluorometry for dynamic assessment of chromatin organization. This type of approach involves both optimal conditions for DNA staining and the use of image cytometry. In this context, this report describes the application of an internal grey-level segmentation method for the assessment of real time modifications of chromatin organization in living cells. These developments are based on a specific, stoichiometric method for nuclear DNA content measurement. Preliminary data obtained from Hela cells suggests the possibility of following variations of nuclear texture (heterogeneity, granularity, condensation, radial distribution) related to the cell cycle progression of cells that are maintained alive.

In situ hybridization in living cells: detection of RNA molecules

Fluorescence hybridization is a widely used technique in cell biology and pathology for detecting specific nucleic acid (DNA and RNA) sequences in fixed cells. This technique does not, however, provide dynamic information on the intracellular behavior of the targeted molecules. The aim of this work was to investigate possibilities of labeled DNA probes for RNA detection in cells that are maintained alive. Such techniques will provide useful tools for studying dynamic cellular processes such as RNA distribution and transport from transcription sites to translation sites by means of fluorescence microscopy. First a reversible, nonperturbing cell permeabilization procedure was developed using streptolysin O. This procedure was used to introduce oligodeoxynucleotides and fluorochrome-labeled DNA probes specific for 28S ribosomal RNA (2.1 kb) into living cells, which were then analyzed by fluorescence microscopy. The results showed that: (i) no increased cell death or growth perturbation was observed after permeabilization, (ii) introduction of a 28S RNA-specific probe (plasmid and oligonucleotides) into living cells led to bright nucleoli and a low cytoplasmic signal, and (iii) negative control probes did not lead to any fluorescent staining. These results indicate that specific hybridization of labeled nucleic acid probes takes place while cells are maintained under normal physiological conditions.

In vitro dynamics of chromatin organization and migration

The organization of eukaryotic chromatin is not static but changes as a function of cell status during processes such as proliferation, differentiation, and migration. DNA quantification has not been used extensively to investigate chromatin dynamics in combination with cellular migration. In this context, an optimized DNA-specific, nonperturbant method has been developed for studying chromatin organization, using the fluorescent vital bisbenzimidazole probe Hoechst 33342: this property has been described by Hamori et al. (1980). Computer-assisted image analysis was used to follow migratory activity and chromatin organization of L929 fibroblasts during in vitro wound healing. Cell movements were analyzed using an optical flow technique, which consists in the calculation of the velocity field of cells and nuclear movements in the frame. This system allows the correlation of cell migration and position in the cell cycle. It makes it possible to study chromatin dynamics using a quantitative analysis of nuclear differentiation reorganization (nuclear texture) and to correlate this with migration characteristics. The present system would be of interest for studying cell-extracellular matrix interactions using differing substrates, and also the migratory response to chemotactic factors. Such a model is a prerequisite for gaining better understanding of drug action.

Specific detection of RNA molecules by fluorescent in situ hybridization in living cells

The antisense therapeutic strategy makes the assumption that sequence-specific hybridization of an oligonucleotide to its target can take place in living cells. The present work provides a new method for the detection of intracellular RNA molecules using in situ hybridization on living cells. The first step consisted in designing nonperturbant conditions for cell permeabilization using streptolysin O. In a second step, intracellular hybridization specificity was evaluated by incorporating various types of fluorescently labeled nucleic acid probes (plasmids, oligonucleotides). Due to its high expression level, the 28S ribosomal RNA was retained as a model. Results showed that: (1) no significant cell death was observed after permeabilization; (2) on living cells, 28S RNA specific probes provided bright nucleoli and low cytoplasmic signal; (3) control probes did not lead to significant fluorescent staining; and (4) comparison of signals obtained on living and fixed cells showed a colocalization of observed fluorescence. These results indicate the feasibility of specific hybridization of labeled nucleic acid probes under living conditions, after a simple and efficient permeabilization step. This new detection method is of interest for investigating the dynamics of distribution of various gene products in living cells, under normal or pathological conditions.

Dynamic functional and structural analysis of living cells: new tools for vital staining of nuclear DNA and for characterisation of cell motion

Increasing interest has been paid to applications of fluorescence measurements to analyze physiological mechanisms in living cells. However, few studies have taken advantage of DNA quantification by fluorometry for dynamic assessment of chromatin organization as well as cell motion during the cell cycle. This approach involves both optimal conditions for DNA staining and cell tracking methods. In this context, this report describes a stoichiometric method for nuclear DNA specific staining, using the bisbenzimidazole dye Hoechst 33342 associated with verapamil, a calcium membrane channel blocker. This method makes it possible to correlate variations of nuclear DNA content with cell motion in cells that are maintained alive. Motion measurement is the second goal of this paper and it explains the snake-spline method, and the associated cell following method.