The association of BMI and physical activity on acetabular dysplasia in children.

BACKGROUND: Acetabular dysplasia is an important pre-disposing factor for osteoarthritis of the hip. However, it is not completely known how acetabular dysplasia develops during childhood. OBJECTIVE: To study the prevalence of acetabular dysplasia and its association with body mass index (BMI) and physical activity in 9 year old children. DESIGN: The population for this cross-sectional study was drawn from the ongoing prospective cohort study: Generation R. 9,778 mothers with a delivery date from March 2002 until January 2006 were enrolled. In a random subgroup of these children Dual-energy X-ray absorptiometry (DXA) scanning was performed at age 9. EXPOSURES: BMI, standardized for the Dutch population and categorized in four groups based on extended international Obesity Task Force cut-offs: underweight, normal, overweight and obesity. Physical activity was based on time spent on playing outdoors, playing sports and walking/cycling to school. MAIN OUTCOMES AND MEASURES: The degree of acetabular dysplasia was determined with the centre-edge angle (CEA) and acetabular depth-width ratio (ADR) in DXA images of the hip. RESULTS: 1,188 DXA images of children's hips were available for analysis. The median age of the children was 9.86 years. Prevalence of dysplasia and mild dysplasia was respectively 6.3%; 25.6% with CEA and 4.8%; 25.0% with ADR. BMI was negatively associated with mild dysplasia (OR 0.80 CI 0.71-0.90). Obese children showed less mild dysplasia compared to normal children (OR 0.48 CI 0.24-0.97) in unadjusted analysis. Physical activity represented by walking to school showed a statistically significant negative association with mild dysplasia (OR 0.87 CI 0.76-0.99). After adjustment for age, ethnicity, sex, first born, breech presentation, birthweight, gestational age and Caesarean section, the patterns of association with dysplasia remained for both BMI and physical activity. CONCLUSIONS: In this study, being overweight and light physical activity were negatively associated with the development of (mild) acetabular dysplasia at the age of 9 years.

Self-amplified photo-induced gap quenching in a correlated electron material.

Capturing the dynamic electronic band structure of a correlated material presents a powerful capability for uncovering the complex couplings between the electronic and structural degrees of freedom. When combined with ultrafast laser excitation, new phases of matter can result, since far-from-equilibrium excited states are instantaneously populated. Here, we elucidate a general relation between ultrafast non-equilibrium electron dynamics and the size of the characteristic energy gap in a correlated electron material. We show that carrier multiplication via impact ionization can be one of the most important processes in a gapped material, and that the speed of carrier multiplication critically depends on the size of the energy gap. In the case of the charge-density wave material 1T-TiSe2, our data indicate that carrier multiplication and gap dynamics mutually amplify each other, which explains-on a microscopic level-the extremely fast response of this material to ultrafast optical excitation.

[Is lutein supplementation inefficacious? Consideration of the scientific opinion on lutein and maintenance of vision and legal classification]. / Lutein--ein unwirksamer Grenzgänger? Betrachtung des Gutachtens der Europäischen Behörde für Lebensmittelsicherheit zu Lutein und der Erhaltung der Sehfunktion und der rechtlichen Produkteinordnung.

The aim of this article is the detailed consideration of the scientific opinion on the substantiation of health claims related to lutein and maintenance of vision, which was published by European Food Safety Authority (EFSA). The findings regarding the efficacy of lutein are important for the legal product classification. Thus, the second part of this paper will focus on products containing lutein regarding the demarcation between foodstuffs and drugs. These products are often used in ophthalmology and therefore the assessment of the legal product classification is also important to know for the attending ophthalmologists. Summing up, it is stated that the national and European law for placing products containing lutein on the market will be harmonised for reasons of clarity, transparency and legal certainty but also providing tighter admission requirements for these kinds of products.

Rapid FlAsH labelling in the budding yeast Saccharomyces cerevisiae.

Live cell imaging of protein distributions is an essential tool in modern cell biology. It relies on the functional labelling of a host protein with a fluorophore, which may either be a genetically fused fluorescent protein or an organic dye binding to the host protein. The biarsenical-tetracysteine system or 'FlAsH-labelling', is based on the high affinity interaction between a biarsenical probe and a small protein tag. This approach has been successfully used for live cell imaging in the budding yeast Saccharomyces cerevisiae. However, the established labelling protocols require a lengthy overnight incubation of the cells with the dye under tightly controlled growth conditions, which severely limits the use of this approach. In this study, we characterize an efficient method for introducing FlAsH-EDT(2) into live budding yeast cells using standard electroporation. The labelling time is reduced from more than 12 h to less than 1 h without compromising the labelling efficiency or cell viability. This approach may be used for cells in different growth phases or grown under different conditions. It may be further extended to other small high affinity probes, thus opening up new possibilities for labelling in budding yeast.

Reversible photoswitching enables single-molecule fluorescence fluctuation spectroscopy at high molecular concentration.

We demonstrate that photoswitchable markers enable fluorescence fluctuation spectroscopy at high molecular concentration. Reversible photoswitching allows precise control of the density of fluorescing entities, because the equilibrium between the fluorescent ON- and the dark OFF-state can be shifted through optical irradiation at a specific wavelength. Depending on the irradiation intensity, the concentration of the ON-state markers can be up to 1,000 times lower than the actual concentration of the labeled molecular entity. Photoswitching expands the range of single-molecule detection based experiments such as fluorescence fluctuation spectroscopy to large entity concentrations in the micromolar range.

Cyclin-dependent kinase 5 is an upstream regulator of mitochondrial fission during neuronal apoptosis.

Under physiological conditions, mitochondrial morphology dynamically shifts between a punctuate appearance and tubular networks. However, little is known about upstream signal transduction pathways that regulate mitochondrial morphology. We show that mitochondrial fission is a very early and kinetically invariant event during neuronal cell death, which causally contributes to cytochrome c release and neuronal apoptosis. Using a small molecule CDK5 inhibitor, as well as a dominant-negative CDK5 mutant and RNAi knockdown experiments, we identified CDK5 as an upstream signalling kinase that regulates mitochondrial fission during apoptosis of neurons. Vice versa, our study shows that mitochondrial fission is a modulator contributing to CDK5-mediated neurotoxicity. Thereby, we provide a link that allows integration of CDK5 into established neuronal apoptosis pathways.

4Pi-confocal microscopy of live cells.

By coherently adding the spherical wavefronts of two opposing lenses, two-photon excitation 4Pi-confocal fluorescence microscopy has achieved three-dimensional imaging with an axial resolution 3-7 times better than confocal microscopy. So far this improvement was possible only in glycerol-mounted, fixed cells. Here we report 4Pi-confocal microscopy of watery objects and its application to the imaging of live cells. Water immersion of 4Pi-confocal microscopy of membrane stained live Escherichia coli bacteria attains a 4.3-fold better axial resolution as compared to the best water immersion confocal microscope. The resolution enhancement results into a vastly improved three-dimensional representation of the bacteria. The first images of live biological samples with an all-directional resolution in the 190-280 nm range are presented here, thus establishing a new resolution benchmark in live-cell microscopy.

Dual-color 4Pi-confocal microscopy with 3D-resolution in the 100 nm range.

We report the development of simultaneous two-color channel recording in 4Pi-confocal microscopy. A marked increase of spatial resolution over confocal microscopy becomes manifested in 4Pi-confocal three-dimensional (3D) data stacks of dual-labeled objects. The fundamentally improved resolution is verified both with densely labeled fluorescence beads as well as with membrane labeled fixed Escherichia coli. The synergistic combination of dual-color 4Pi-confocal recording with image restoration results in dual-color imaging with a 3D resolution in the 100 nm range.

EFGP and DsRed expressing cultures of Escherichia coli imaged by confocal, two-photon and fluorescence lifetime microscopy.

The green fluorescent protein (GFP) has become an invaluable marker for monitoring protein localization and gene expression in vivo. Recently a new red fluorescent protein (drFP583 or DsRed), isolated from tropical corals, has been described [Matz, M.V. et al. (1999) Nature Biotech. 17, 969-973]. With emission maxima at 509 and 583 nm respectively, EGFP and DsRed are suited for almost crossover free dual color labeling upon simultaneous excitation. We imaged mixed populations of Escherichia coli expressing either EGFP or DsRed by one-photon confocal and by two-photon microscopy. Both excitation modes proved to be suitable for imaging cells expressing either of the fluorescent proteins. DsRed had an extended maturation time and E. coli expressing this fluorescent protein were significantly smaller than those expressing EGFP. In aging bacterial cultures DsRed appeared to aggregate within the cells, accompanied by a strong reduction in its fluorescence lifetime as determined by fluorescence lifetime imaging microscopy.

Fluorescence microscopy with diffraction resolution barrier broken by stimulated emission.

The diffraction barrier responsible for a finite focal spot size and limited resolution in far-field fluorescence microscopy has been fundamentally broken. This is accomplished by quenching excited organic molecules at the rim of the focal spot through stimulated emission. Along the optic axis, the spot size was reduced by up to 6 times beyond the diffraction barrier. The simultaneous 2-fold improvement in the radial direction rendered a nearly spherical fluorescence spot with a diameter of 90-110 nm. The spot volume of down to 0.67 attoliters is 18 times smaller than that of confocal microscopy, thus making our results also relevant to three-dimensional photochemistry and single molecule spectroscopy. Images of live cells reveal greater details.

Comparative study of the roughness of optical surfaces and thin films by use of X-ray scattering and atomic force microscopy.

The surface roughness of polished glass substrates and optical thin-film coatings is studied with atomic force microscopy and x-ray scattering. It is demonstrated that both methods permit the determination of power spectral density functions in a wide range of spatial frequencies. The results are in good quantitative agreement.

Interfacial roughness and related scatter in ultraviolet optical coatings: a systematic experimental approach.

For a variety of UV optical coatings, surface roughness was measured by use of an atomic-force microscope (AFM) to study its dependence on the film material and thickness, coating design, and deposition process. After analyzing the corresponding power spectral density functions, we propose a simple classification model for coatings according to the contributions of substrate roughness and intrinsic film roughness to the scattering. Results of scattering measurements on different types of coatings are presented and are found to be in good agreement with predictions based on the AFM data. Consequences for a scatter reduction strategy are discussed.

Quantification and genotyping of serum HCV-RNA in patients with chronic hepatitis C undergoing interferon treatment.

Quantification of serum HCV-RNA and HCV genotyping was studied in 27 patients with chronic hepatitis C undergoing interferon treatment. Pretreatment serum HCV-RNA levels were quantified using competitive RT-PCR and compared to a quantitative RT-PCR assay based on co-amplification of HCV-RNA with a synthetic RNA standard. HCV genotyping was performed using a line probe reversed hybridisation assay or direct solid-phase sequencing. This study shows the feasibility of performing HCV-RNA quantification. RT-PCR based on co-amplification HCV-RNA titer less than 6 x 10(4) genome equivalents/ml serum did correlate with a complete sustained response to alpha interferon in chronic hepatitis C. HCV genotype 1b was alpha predominantly associated with a high non-responder rate. Future prospective trials will be required to evaluate quantitative HCV-RNA levels and HCV genotyping as response predicting parameters for interferon-treatment.

Combination of surface characterization techniques for investigating optical thin-film components.

To meet the requirements of comprehensively characterizing the morphology of thin films and substrates, a suitable combination of different measuring techniques should be chosen, i.e., a nonoptical surface profile measurement should be used together with optical analysis. It is demonstrated on selected examples of fluoride and oxide films that the use of atomic force microscopy and light scattering fulfills the demand of appropriate quantitative characterization over a sufficiently large range of bandwidths.

Quantitation of HCV-replication using one-step competitive reverse transcription-polymerase chain reaction and a solid phase, colorimetric detection method.

A solid phase assay for the colorimetric detection of competitively amplified HCV-cDNA has been established and used to investigate clinical samples from patients with chronic hepatitis. The assay is based on the reduction in the amplification of an hepatitis C virus-related competitor molecule by wild-type hepatitis C virus during polymerase chain reaction. The internal standard contains a lac operator sequence, allowing the amount of amplified competitor to be determined using a lac I-repressor/beta-galactosidase fusion protein. The reduction in the amplification of competitor is dependent upon the concentration of HCV-RNA in the original sample. External hepatitis C virus wild-type standards are used to calibrate each concurrently tested set of patients. We present and discuss the potential benefit, but also the limitations of this new approach for quantifying hepatitis C virus viremia. In 47 serum samples from 28 patients with chronic hepatitis C virus infection, including five repeatedly tested alpha HCV positive patients under interferon therapy, viral titer was determined. Sera from nine healthy blood donors served as controls. The sensitivity and specificity of this procedure are identical to those of conventional nested polymerase chain reaction. As both internal and external standards are used in every assay and final detection of amplicons can be carried out in microtiter plates, this reliable and time-saving test system may be routinely applied for monitoring antiviral treatment or for studying the relation of plus- and minus-stranded HCV-RNA in infected tissues.