Fructose, trehalose and sorbitol malabsorption Montalto, M; Gallo, A; Ojetti, V ...
European review for medical and pharmacological sciences,
11/2013, Letnik:
17 Suppl 2
Journal Article
Recenzirano
Carbohydrate malabsorption is a frequent clinical condition, often associated with abdominal symptoms. Although lactose represents the most commonly malabsorbed sugar, also other carbohydrates, such ...as fructose, trehalose and sorbitol may be incorrectly absorbed in the small intestine. Fructose malabsorption seems more common in patients with functional bowel disease, even if randomized and controlled studies on these topic were few and on small samples. Interpretation of breath hydrogen testing is difficult. In particular, neither studies comparing this test with a gold standard, nor validated doses and concentrations to be used, are available. Trehalose malabsorption due to trehalase deficiency represents a very rare condition and available studies do not support its relevance in clinical practice. Sorbitol absorption is dose and concentration related, and depends on the entity of intestinal absorption surface. Nevertheless, the finding of its malabsorption is not expression of a specific cause of intestinal bowel damage. From available data, it is not possible to draw definite conclusions about clinical relevance of fructose, trehalose and sorbitol malabsorption, as well as, about diagnostic accuracy of commonly used tests to detect all these conditions. On the other hand, in patients who refer abdominal discomfort after ingestion of different carbohydrate-containing foods, a small intestinal bacterial overgrowth, should be promptly considered. This is because the large amount of intestinal bacteria may unspecifically ferment sugars, causing an abnormal H2 production and consequently a misleading diagnosis of sugar malabsorption.
Dynamical interactions in binary systems are thought to play a major role in the formation of extreme horizontal branch stars (EHBs) in the Galactic field. However, it is still unclear if the same ...mechanisms are at work in globular clusters (GCs), where EHBs are predominantly single stars. Here, we report on the discovery of a unique close binary system (period ~ 1.61 days) in the GC NGC 6752, comprising an EHB and a main-sequence companion of 0.63 + or - 0.05 M sub(middot in circle). Such a system has no counterpart among nearly 200 known EHB binaries in the Galactic field. Its discovery suggests that either field studies are incomplete, missing this type of system possibly because of selection effects, or that a particular EHB formation mechanism is active in clusters but not in the field.
Using two HST/ACS data sets that are separated by about two years has allowed us to derive the relative proper motion for the Sagittarius dwarf irregular (SagDIG) and reduce the heavy foreground ...Galactic contamination. The proper-motion decontaminated SagDIG catalog provides a much clearer view of the young red-supergiant and intermediate-age asymptotic giant branch populations. Previously identified carbon- and oxygen-rich star samples, which are based on narrow-band filter photometry, were complemented by membership criteria. We report identifying three Milky Way carbon-rich dwarf stars, which probably belong to the thin disk, and pointing to the high incidence of this class at low Galactic latitudes. We conclude that there is no convincing evidence that the SagDIG H I hole is the result of stellar feedback and that gravitational and thermal instabilities in the gas are the most likely mechanism for its formation.
Complement consists of a complex cascade of proteins involved in innate and adaptive immunity. The cascade can be activated through 3 distinct mechanisms, designated the classical, alternative, and ...lectin pathways. Although complement is widely accepted as participating in the pathophysiology of ischemia-reperfusion injury, the specific role of the lectin pathway has not been addressed.
Monoclonal antibodies (mAbs; P7E4 and 14C3.74, IgG1kappa isotypes) were raised against rat mannose-binding lectin (rMBL). Both mAbs recognized rMBL-A by Western analysis or surface plasmon resonance. P7E4, but not 14C3.74, exhibited a concentration-dependent inhibition of the lectin pathway, with maximal effect at 10 microg/mL. In vivo, rats were subjected to 30 minutes of left coronary artery occlusion and 4 hours of reperfusion. Complement C3 deposition was greatly attenuated in hearts pretreated with P7E4 compared with 14C3.74-treated hearts. Pretreatment with P7E4 (1 mg/kg) significantly reduced myocardial creatine kinase loss (48%), infarct size (39%), and neutrophil infiltration (47%) compared with 14C3.74-treated animals. In addition, P7E4 pretreatment significantly attenuated the expression of proinflammatory genes (intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and interleukin-6) after ischemia-reperfusion.
The lectin complement pathway is activated after myocardial ischemia-reperfusion and leads to tissue injury. Blockade of the lectin pathway with inhibitory mAbs protects the heart from ischemia-reperfusion by reducing neutrophil infiltration and attenuating proinflammatory gene expression.
The old and metal-rich open cluster NGC 6253 was observed with the Fibre Large Array Multi Element Spectrograph (FLAMES) multi-object spectrograph during an extensive radial velocity campaign ...monitoring 317 stars with a median of 15 epochs per object. All the targeted stars are located along the upper main sequence of the cluster between 14.8 < V < 16.5. Fifty nine stars are confirmed cluster members both by radial velocities and proper motions and do not show evidence of variability. We detected 45 variable stars among which 25 belong to NGC 6253. We were able to derive an orbital solution for four cluster members (and for two field stars) yielding minimum masses in between ∼90 M
J and ∼460 M
J and periods between 3 and 220 d. Simulations demonstrated that this survey was sensitive to objects down to 30 M
J at 10 days orbital periods with a detection efficiency equal to 50 per cent. On the basis of these results we concluded that the observed frequency of binaries down to the hydrogen burning limit and up to 20 d orbital period is around (1.5 ± 1.3) per cent in NGC 6253. The overall observed frequency of binaries around the sample of cluster stars is (13 ± 3) per cent. The median radial velocity precision achieved by the GIRAFFE spectrograph in this magnitude range was around ∼240 m s− 1 (∼180 m s− 1 for UVES). Based on a limited follow-up analysis of seven stars in our sample with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph we determined that a precision of 35 m s− 1 can be reached in this magnitude range, offering the possibility to further extend the variability analysis into the substellar domain. Prospects are even more favourable once considering the upcoming ESPRESSO spectrograph at VLT.
We present a model-independent technique for calculating the time of mid-transits. This technique, named “barycenter method”, uses the light-curve’s symmetry to determine the transit timing by ...calculating the transit light-curve barycenter. Unlike the other methods of calculating mid-transit timing, this technique does not depend on the parameters of the system and central star. We demonstrate the capabilities of the barycenter method by applying this technique to some known transiting systems including several Kepler confirmed planets. Results indicate that for complete and symmetric transit lightcurves, the barycenter method achieves the same precision as other techniques, but with fewer assumptions and much faster. Among the transiting systems studied with the barycenter method, we focus in particular on LHS 6343C, a brown dwarf that transits a member of an M+M binary system, LHS 6343AB. We present the results of our analysis, which can be used to set an upper limit on the period and mass of a possible second small perturber.
Transmission spectroscopy during planetary transits, which is based on the measurements of the variations of the planet-to-star radius ratio as a function of wavelength, is a powerful technique to ...study the atmospheric properties of transiting planets. One of the main limitations of this technique is the effects of stellar activity, which up until now, have been taken into account only by assessing the effect of non-occulted stellar spots on the estimates of the planet-to-star radius ratio. In this paper, we study the impact of the occultation of a stellar spot and plage on the transmission spectra of transiting exoplanets for the first time. We simulated this effect by generating a large number of transit light curves for different transiting planets, stellar spectral types, and different wavelengths. Results of our simulations indicate that the anomalies inside the transit light curve can lead to a significant underestimation or overestimation of the planet-to-star radius ratio as a function of wavelength. At short wavelengths, the effect can reach to a difference of up to 10% in the planet-to-star radius ratio, mimicking the signature of light scattering in the planetary atmosphere. Atmospheric scattering has been proposed to interpret the increasing slopes of transmission spectra toward blue for exoplanets HD 189733b and GJ 3470b. Here, we show that these signatures can be alternatively interpreted by the occultation of stellar plages. Results also suggest that the best strategy to identify and quantify the effects of stellar activities on the transmission spectrum of a planet is to perform several observations during the transit epoch at the same wavelength. This will allow for identifying the possible variations in transit depth as a function of time due to stellar activity variability.
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