Structural movies of the gradual spin-crossover in a molecular complex at various physical scales.

The thermally induced Spin-CrossOver (SCO) undergone by the mononuclear iron(ii) complex [Fe(PM-AzA)2(NCS)2] (PM = N-2'-pyridylmethylene, AzA = 4-(phenylazo)aniline) is fully pictured by a quasi-continuous structural determination all along the spin-state modification within the sample. This large scale multi-temperature Single-Crystal X-Ray Diffraction (SCXRD) investigation leads to making structural movies. The latter reveal or confirm some features of the SCO that are subsequently validated by the same systematic investigation performed on a zinc isostructural analogue complex. Notably, the continuous views of the temperature dependencies of the unit-cell parameters, the dilatation tensors, the metal coordination sphere geometry and the intermolecular distances confirm a few of the structure-property relationships already known for SCO materials. In parallel, the examination of the temperature dependencies of the atomic coordinates and the atomic displacement parameters reveals unexpected behaviours in this gradual SCO material such as antagonistic atomic movements due to the single SCO and the pure thermal effects.

Uranium Hydridoborates: Synthesis, Magnetism, and X-ray/Neutron Diffraction Structures.

While uranium hydridoborate complexes containing the [BH4](-) moiety have been well-known in the literature for many years, species with functionalized borate centers remained considerably rare. We were now able to prepare several uranium hydridoborates (1-4) with amino-substituted borate moieties with high selectivity by smooth reaction of [Cp*2UMe2] (Cp* = C5Me5) and [Cp'2UMe2] (Cp' = 1,2,4-tBu3C5H2) with the aminoborane H2BN(SiMe3)2. A combination of nuclear magnetic resonance spectroscopy, deuteration experiments, magnetic SQUID measurements, and X-ray/neutron diffraction studies was used to verify the anticipated molecular structures and oxidation states of 1-4 and helped to establish a linear tridentate coordination mode of the borate anions.

Influence of blood glucose on heart rate and cardiac autonomic function. The DESIR study.

OBJECTIVES: To evaluate in a general population, the relationships between dysglycaemia, insulin resistance and metabolic variables, and heart rate, heart rate recovery and heart rate variability. METHODS: Four hundred and forty-seven participants in the Data from an Epidemiological Study on the Insulin Resistance syndrome (DESIR) study were classified according to glycaemic status over the preceding 9 years. All were free of self-reported cardiac antecedents and were not taking drugs which alter heart rate. During five consecutive periods: rest, deep breathing, recovery, rest and lying to standing, heart rate and heart rate varability were evaluated and compared by ANCOVA and trend tests across glycaemic classes. Spearman correlation coefficients quantified the relations between cardio-metabolic risk factors, heart rate and heart rate varability. RESULTS: Heart rate differed between glycaemic groups, except during deep breathing. Between rest and deep-breathing periods, patients with diabetes had a lower increase in heart rate than others (P(trend) < 0.01); between deep breathing and recovery, the heart rate of patients with diabetes continued to increase, for others, heart rate decreased (P(trend) < 0.009). Heart rate was correlated with capillary glucose and triglycerides during the five test periods. Heart rate variability differed according to glycaemic status, especially during the recovery period. After age, sex and BMI adjustment, heart rate variability was correlated with triglycerides at two test periods. Change in heart rate between recovery and deep breathing was negatively correlated with heart rate variability at rest, (r=-0.113, P < 0.05): lower resting heart rate variability was associated with heart rate acceleration. CONCLUSIONS: Heart rate, but not heart rate variability, was associated with glycaemic status and capillary glucose. After deep breathing, heart rate recovery was altered in patients with known diabetes and was associated with reduced heart rate variability. Being overweight was a major correlate of heart rate variability.

Down to the quantum limit at the neutral-to-ionic phase transition of (BEDT-TTF)-(ClMe-TCNQ): symmetry analysis and phase diagram.

We report on the neutral-to-ionic (N-I) phase transition in the one-dimensional organic complex (BEDT-TTF)-(ClMeTCNQ). The X-ray studies at room temperature show that the neutral phase of (BEDT-TTF)-(ClMeTCNQ) is already characterized by a polar long-range ordering, at variance with other charge-transfer compounds comprising noncentrosymmetric molecules. From a detailed neutron diffraction study of this complex under high pressure, we present the phase diagram of the N-I transition down to the quantum limit. We discuss the symmetry breaking associated with the transition and the evolution of its first-order character under pressure.

[Prevalence of symptoms of sleep apnea syndrome. Study of a French middle-aged population]. / Prévalence des symptômes du syndrome d'apnées du sommeil. Etude dans une population française d'âge moyen.

OBJECTIVE: To study the prevalence of symptoms of sleep apnoea syndrome (SAS) in a large French middle-aged population and to establish what proportion have symptoms that justify further investigation with a sleep study. METHODS: We performed a cross-sectional study of 2,195 men and 2,247 women, 33 to 69 year old (DESIR. cohort) recording responses to a self-administered "sleep" questionnaire and a general questionnaire including socio-economic characteristics and lifestyle factors. RESULTS: The prevalence of symptoms in men and women were respectively: snoring frequently (28%, 14%), frequent daytime sleepiness (14%, 18%) and frequent apnoeas (5%, 2%). Overall, 8.5% of men and 6.3% of women reported a pattern of symptoms suggestive of OSA, as they snored and had daytime sleepiness and/or apnoeas. This pattern was associated, for both sexes, with age, body mass index and after adjustment on these two factors, to a mediocre self-reported health status and treatment with benzodiazepines or other sedatives. For men only, the OSA pattern of symptoms was also associated with, hypertension, alcohol consumption and smoking. CONCLUSION: Snoring, daytime hypersomnolence and witnessed apnoeas are symptoms frequently observed in the general population. Subjects with a combination of these abnormalities suggesting a high probability of sleep apnoea syndrome and in whom a sleep study is warranted represent 7.5% of the adult population.

Weight change and changes in the metabolic syndrome as the French population moves towards overweight: the D.E.S.I.R. cohort.

BACKGROUND: How weight change affects the metabolic syndrome (MS) and its parameters is unknown, particularly, in a leaner European population such as the French prospective D.E.S.I.R. cohort. METHODS: In 3770 D.E.S.I.R. participants (sex ratio=1) averaging 47.5 years (range 30-64), with measured weight and MS parameters at baseline (D0) and at 6 year follow-up (D6), we assessed this relationship across five weight-change classes, using stable weight as the referent group (-2 to +2 kg). We used analysis-of-covariance to assess changes in each MS parameter and logistic regression to assess incident MS, according to the National Cholesterol Education Program (NCEP). We also assessed weight-change effect on MS status between D0 and D6. RESULTS: At D0, average weight was 68.4 kg (SD 12.3); BMI was 24.8 kg/m2 (SD 3.5). From D0-D6, the cohort gained a mean 2.1 kg (median 2.0; SD 4.4). After adjustment for age and D0 weight, there was a strong linear relationship with weight change and worsening of the following MS parameters at D6: fasting insulin, waist girth, fasting glucose, fasting triglycerides, HDL cholesterol, and systolic and diastolic blood pressure (P<0.0001). After age adjustment, for every kilogram gained over 6 years, risk of developing the NCEP Syndrome increased 22% (OR 1.22; 95% CI 1.18-1.25). NCEP-MS was incident in 3% of those with stable weight compared with 21% among those gaining >9 kg; 10% of those who lost >2 kg reverted to non-NCEP-MS. CONCLUSIONS: All continuous MS measures are linearly related to weight change, and MS can resolve with modest weight loss, underscoring the importance of maintaining lifelong normal weight.

Prescreening tools for diabetes and obesity-associated dyslipidaemia: comparing BMI, waist and waist hip ratio. The D.E.S.I.R. Study.

OBJECTIVE: To compare the sensitivities of BMI, waist circumference and waist hip ratio (WHR) in identifying subjects who should be screened for diabetes and/or for obesity-associated dyslipidaemia. DESIGN: Cross-sectional study. SETTING: Central-western France. PARTICIPANTS: More than 3000 men and women, aged 40-64 years, from the French study: data from an epidemiological study on the insulin resistance syndrome (D.E.S.I.R.). MAIN OUTCOME MEASURES: Sensitivity and specificity for screened diabetes (fasting plasma glucose>or=7.0 mmol/l) and screened dyslipidaemia (triglycerides>or=2.3 mmol/l and/or HDL-cholesterol <0.9/1.1 mmol/l (men/women)) according to BMI, waist circumference and WHR. RESULTS: Sensitivities increased as more corpulent subjects were screened, but they increased slowly after screening the top 30%: body mass index (BMI)>or=27/26 kg/m(2) (men/women) or waist >or=96/83 cm or WHR>or=0.96/0.83. These values were chosen as thresholds. In men, BMI had a nonsignificantly higher sensitivity than waist or WHR for both diabetes and dyslipidaemia (77 vs 74 and 66% P<0.3, 0.09; 56 vs 54 and 49% P<0.5, 0.16). For women, waist had a slightly higher sensitivity than BMI or WHR (82 vs 77 and 77% P<0.8, 0.7) for diabetes; for dyslipidaemia, waist and WHR had similar sensitivities, higher than for BMI (65 and 67 vs 54% P<0.16, 0.13). CONCLUSIONS: We propose that for screening in a French population 40-64 years of age, the more obese 30% of the population, identified either by BMI, waist or WHR be screened for diabetes and obesity-associated dyslipidaemia.

Neutron Laue and X-ray diffraction study of a new crystallographic superspace phase in n-nonadecane-urea.

Aperiodic composite crystals present long-range order without translational symmetry. These materials may be described as the intersection in three dimensions of a crystal which is periodic in a higher-dimensional space. In such materials, symmetry breaking must be described as structural changes within these crystallographic superspaces. The increase in the number of superspace groups with the increase in the dimension of the superspace allows many more structural solutions. This is illustrated in n-nonadecane-urea, revealing a fifth higher-dimensional phase at low temperature.

Microalbuminuria and markers of the atherosclerotic process: the D.E. S.I.R. study.

The relationship between microalbuminuria and tissue-type plasminogen activator antigen (tPA-ag) and fibrinogen was evaluated in non-diabetic subjects. Subjects were participants of the D.E.S.I. R. (Data from an Epidemiological Study on the Insulin Resistance syndrome) Study. Analyses were carried out on 2248 women and 2402 men for fibrinogen and on 272 women and 284 men for tPA-ag. Microalbuminuria was defined as urinary albumin concentration greater than 20 mg/l. Men with microalbuminuria had a 6% higher fibrinogen concentration than those without (3.07 g/l (95% confidence interval: 2.99,3.15) vs. 2.89 g/l (2.87,2.91), adjusted for age and smoking). This relationship existed in hypertensive as well as non-hypertensive subjects. The association between microalbuminuria and tPA-ag existed only in hypertensive men, those with microalbuminuria having a 21% higher tPA-ag than those without (4.39 ng/ml (3.70,5.08) vs. 3.63 ng/ml (3.32,3.94), adjusted for age and smoking). Adjustment for other risk markers for cardiovascular disease did not change the results. There was no relationship between microalbuminuria and these haemostatic factors in women. The results of this study suggest that in non-diabetic men, microalbuminuria is associated with fibrinogen, but with tPA-ag only when concomitant with hypertension.

[Study of the motivation of physicians participating in public health research]. / Enquête de motivation sur la participation des médecins à une recherche en santé publique.

In order to explore practitioners' motivations to participate in epidemiological research, a study was conducted among doctors who had been requested to provide clinical information on their patients included in the group study DESIR in the Inde and Loire regions of France. Six semi-structured individual interviews were carried out by two sociologists, and were then followed-up by 216 questionnaires, 80 of which were completed and analysed. Finally, 18 telephone interviews were conducted to complete the data collected. Reasons given for participating in epidemiological studies are mainly the perceived scientific interest, relevance for public health and the feeling of being a partner in the research. The obstacles seem to be the vague image of the promoter, ignorance of the DESIR study's objectives, lack of direct contact for communicating information, and the mixture and confusion between filling out the study's questionnaire and handling administrative constraints in general. Therefore, better communication, centred on the concept of partnership between research and practical medicine, informing on the usefulness of knowledge from epidemiological studies for the practice of medicine, and clarifying the promoter's role, could improve the level of participation from general practitioners.

Practical way to assess metabolic syndrome using a continuous score obtained from principal components analysis.

AIMS/HYPOTHESIS: We devised a practical continuous score to assess the metabolic syndrome, and assessed whether this syndrome score predicts incident diabetes and cardiovascular disease. SUBJECTS AND METHODS: Among 5,024 participants of the Data from an Epidemiological Study on the Insulin Resistance Syndrome (D.E.S.I.R.) cohort, we defined a metabolic syndrome score by the first principal component (PC1), using only the correlations between continuous metabolic syndrome measures (glucose, waist circumference, triglycerides, and systolic blood pressure). This metabolic syndrome score was highly correlated with a similar score also including insulin and HDL cholesterol (r ( s )=0.94). Over 9 years of follow-up, incident diabetes and cardiovascular disease (CVD) were predicted by logistic regression using the simpler metabolic syndrome score. RESULTS: The means of the metabolic syndrome measures differed between men and women. Nevertheless, as the degree of variance explained and the PC1 coefficients were remarkably similar, we used a common metabolic syndrome score. The metabolic syndrome score explained 50% of the variance of the metabolic syndrome measures, and waist circumference had the highest correlation (0.59) with this score. Each standard deviation increase in the metabolic syndrome score was associated with a markedly increased age-adjusted risk of developing diabetes (odds ratios: men 3.4 [95% CI 2.6-4.4]; women 5.1 [3.6-7.2]) and with increased incident CVD of 1.7 (1.4-2.1) in men and 1.7 (1.0-2.7) in women. CONCLUSIONS/INTERPRETATION: Our results, which should be confirmed in other populations, suggest that it is possible to evaluate the risk of the metabolic syndrome in a pragmatic fashion with a continuous score, obtained from principal components analysis of the basic, continuous syndrome measures.

One-dimensional fluctuating nanodomains in the charge-transfer molecular system TTF-CA and their first-order crystallization.

We report on the direct observation by x-ray diffuse scattering measurements of thermally induced one-dimensional nanoscale ordered fluctuations in the mixed-stack charge-transfer molecular system tetrathiafulvalene-p chloranil (TTF-CA), the prototype for the neutral-ionic phase transition. The unusual physical properties of this compound are considered to be driven by such one-dimensional excitations. The results are discussed in relation to previous experimental and theoretical experiments both at thermal equilibrium and under light irradiation.