Is nondipping in 24 h ambulatory blood pressure related to cognitive dysfunction?

OBJECTIVE: Associations between the outcome of 24 h ambulatory monitoring and cognitive performance were studied in order to evaluate the potential relevance of ambulant blood pressure status to brain function. It was hypothesized that a small daytime-night-time difference in mean blood pressure (nondipping) is associated with reduced cognitive performance, in line with studies in hypertensive subjects that have reported associations between nondipping and target-organ damage. METHODS: The study followed a cross-sectional design and was part of a larger research programme on determinants of cognitive aging (Maastricht Aging Study, MAAS). A group of 115 community residents aged 28-82 years was recruited from a general practice population and screened for cardiovascular events and medication use. All underwent 24 h blood pressure monitoring. Cognitive performance was measured with tests of verbal memory, attention, simple speed and information processing speed. RESULTS: Mean daytime or night-time levels of both systolic and diastolic blood pressure were unrelated to cognitive outcome, when age, sex and educational level were controlled for. Differences between mean daytime and night-time blood pressure (based on both narrow and wide measurement intervals for day and night-time periods) were positively associated with memory function (5-9% of additional variance explained) and one sporadic positive association was found on the sensorimotor speed score (4%). Nondippers (n=15) showed lower levels of both memory and sensorimotor speed scores. CONCLUSIONS: Ambulatory blood pressure status was not associated with cognitive performance. A reduced nocturnal blood pressure drop was associated with quite specific cognitive deficits, but the underlying mechanism remains to be determined.     

Epidemiology and economic impact of heart failure in France

There are little epidemiological data available about heart failure in France, despite its considerable impact on the system of health care and the fact that this problem will become even more acute in the future. Here are some important statistics: in France, there are about 500,000 people suffering from heart failure with about 120,000 new cases every year. The incidence increases from 4% in men and 3% in women of 55 to 64 years of age to 50% in men and 85% in women of 85 to 94 years of age. The average age of diagnosis is 73.5 years: two thirds of patients are over 70 years of age. There are about 3.5 million consultations and 150,000 hospital admissions for heart failure per year. The average length of hospital stay is 11 days. There are more than 32,000 deaths per year from heart failure. The cost of treating heart failure represents more than 1% of total medical expenses. Heart failure is a major problem of public health which is on the increase. This should incite physicians to provide optimal treatment for those affected and to place greater emphasis on preventive measures.     

Topology of the principal EEG elements of sleep analyzed by analogue filters

In order to compare the venodilation effect of morphine in normal individuals (22) with that in patients (13) with heart failure morphine sulfate (0.1 mg/kg) was administered to 13 patients with mild pulmonary edema. After morphine congestive symptoms improved and venodilation was induced as determined by two independent techniques: venous pressure fell 10.2 mm Hg by the isolated hand technique and the venous volume of the forearm increased by 0.48 cc/100 ml, measured by equilibration technique. Neither finding differed from those in normal individuals. Reflex venoconstriction noted on the taking of a single deep breath was unaffected by morphine administration and was similar to that observed in normal subjects. Since the drug morphine sulfate does not cause a major pooling of blood in the limbs, the favorable effect of narcotics in patients with pulmonary edema must be caused by other mechanisms such as splanchnic pooling, afterload reduction or reduced breathing effort.     

A rapid method for determining the antimicrobial activity of novel natural molecules

Preservatives used in the Agro-food industries may be of natural origin or obtained chemically. Because of the increasing interest of consumers in food products that contain only natural ingredients, studies on preservative molecules of natural origin, such as organic acids or peptides, have been reported in the past several years. Such studies, which require numerous assays, may be limited by the large amount of molecules required. Microscale assays provide an opportunity for testing natural components available in low quantity. This study examined a rapid method that used microplates for the evaluation of anti-microbial substances. The method was validated using five foodborne pathogens. It required a low amount of product and was convenient for the determination of correlations between the bacterial growth inhibition and concentration of the antimicrobial substance.     

Isolation and characterization of copolymers of beta-lactoglobulin, alpha-lactalbumin, kappa-casein, and alphas1-casein generated by pressurization and thermal treatment of raw milk

Raw skim milk was submitted to high pressure (300 to 600 MPa) and temperature (4 to 70 degrees C) treatments for 2 or 5 min. The combined effects of pressure and temperature on milk proteins induced structural changes and polymer and copolymer formation characterized by anion-exchange and size-exclusion fast protein liquid chromatography and electrophoretic techniques. Approximately half of the beta-lactoglobulin formed polymers, and the other half formed large copolymers, mainly with kappa-casein, alpha-lactalbumin via intermolecular disulfide bond exchange, and alpha(s1)-casein via physicochemical interactions, in proportions of 1.0:0.7:0.3:0.1, respectively. Minor whey proteins (serum albumin, immunoglobulins, and lactoferrin) also participated in the formation of the copolymers but to a lesser extent. Two populations of the copolymers were found with apparent molecular masses ranging from 440 to 2000 kDa for the first and more than 2000 kDa for the second. On the contrary, for heated milks the aggregation kinetics obtained by combination of high pressure and thermal treatment were very fast, as no intermediates such as dimers and small size oligomers were observed after pressurization, whatever the temperature studied. Lactosylation of proteins as well as proteolysis were very limited. A beta-casein amino-terminal peptide of 22 kDa was specifically recovered in milk samples treated under the more drastic conditions (500 MPa/55 degrees C per 5 min and 600 MPa/70 degrees C per 5 min) and might have been generated by neutral proteases such as elastase released from somatic cells present in milk. No casein was released from the micelle whatever the combination of high pressure and temperature studied.     

Remote-sensing reflectance of turbid sediment-dominated waters. Reduction of sediment type variations and changing illumination conditions effects by use of reflectance ratios

Variations of sediment type (grain size and refractive index) and changing illumination conditions affect the reflectance signal of coastal waters and limit the accuracy of sediment-concentration estimations from remote-sensing measurements. These effects are analyzed from numerous in situ remote-sensing measurements carried out in the Gironde and Loire Estuaries and then reduced and partly eliminated when reflectance ratios between the near infrared and the visible are considered. These ratios showed high correlation with the sediment concentration. On the basis of the obtained relationships, performing correspondence functions were established that allow an accurate estimation of suspended sediments in the estuaries from Système Probatoire d'Observation de la Terre, Landsat, and Sea-Viewing Wide Field-of-View Sensor data, independently of the date of acquisition.     

On the designing of densely dispersion-managed optical fiber systems for ultrafast optical communication

We present some theoretical and experimental results which suggest the possibility of constructing a non-empirical methodology of designing optical transmission systems with ultra high bit-rate per channel. Theoretically, we present an average dispersion decreasing densely dispersion-managed (A4dm) fiber system, which exhibits many advantages over the densely dispersion-managed fiber system, such as the possibility of transmitting chirp-free Gaussian pulses at 160 Gbit/s per channel over transoceanic distances, with a reduced energy and minimal intra-channel interaction. Experimentally we present generation of a 160-GHz picosecond pulse train at 1550 nm using multiple four-wave mixing temporal compression of an initial dual frequency beat signal in the anomalous-dispersion regime of a non-zero dispersion shifted fiber. A complete intensity and phase characterization of the pulse train by means of a frequency-resolved optical gating technique is achieved, showing generation of transform-limited pedestal-free Gaussian pulses.     

Standardized MR protocol for the evaluation of MRA sequences and/or contrast agents effects in high-degree arterial stenosis analysis

Purpose To investigate the relative role of high resolution (spatial or temporal) magnetic resonance angiography (MRA) sequence and of contrast agent properties in the evaluation of high-degree arterial stenosis. Methods We qualitatively and quantitatively studied both 50 and 95% (300 μm diameter) stenosis of a 6 mm arterial phantom with two contrast agents (CA), Gd-DOTA (r₁ =2.9 mM⁻¹ s⁻¹) versus P760 (r₁ =25 mM⁻¹ s⁻¹) at several CA concentrations, including arterial peak concentration after injection of either a single or double dose of CA, using either a high temporal (booster) or high spatial (HR) resolution 3D MRA sequences. Experimental data were then compared to theoretical data. Results With the 3D HR sequence, both visual and quantitative analysis were significantly better compared to the 3D booster sequence, at each phantom diameter. Quantitative analysis was significantly improved by injection of a double versus a single dose of each CA (Gd-DOTA or P760), primarily in high degree stenosis. Conclusion Combined MRA spatial resolution and high CA efficiency are mandatory to correctly evaluate high degree stenosis.     

Development of molecular hydrogen-bonding potentials (MHBPs) and their application to structure-permeation relations

Hydrogen bonds are major forces of recognition in biochemistry and molecular pharmacology; they are an essential component of intermolecular interactions and determine to a significant extent the 3D-structure of bio-macromolecules. To explore three-dimensional H-bonding properties, a new tool called Molecular Hydrogen-Bonding Potentials (MHBPs) was created. The development of this tool is based on a stepwise procedure similar to the one used successfully to generate the Molecular Lipophilicity Potential (MLP). First, a H-bonding fragmental system was developed starting from published solvatochromic parameters. An atomic H-bonding donor fragmental value (alpha) is associated to each hydrogen atom in a polar moiety. Similarly, an atomic H-bonding acceptor fragmental value (beta) is associated to each polar atom. A distance function and an angle function were defined to take into account variations of the MHBPs in space. The fragmental system and the geometric functions were then combined to generate the MHBPs. These are calculated at each point of an adequate molecular surface or on a three-dimensional grid. The MHBPs were compared with GRID interactions energies and correlated with success to oral drug absorption data. Available examples demonstrate that the MHBPs are a promising computational tool in drug design. Their combination with CoMFA and VolSurf is being studied.