Oral tolerance attenuates changes in in vitro lung tissue mechanics and extracellular matrix remodeling induced by chronic allergic inflammation in guinea pigs

Recent studies emphasize the presence of alveolar tissue inflammation in asthma. Immunotherapy has been considered a possible therapeutic strategy for asthma, and its effect on lung tissue had not been previously investigated. Measurements of lung tissue resistance and elastance were obtained before and after both ovalbumin and acetylcholine challenges. Using morphometry, we assessed eosinophil and smooth muscle cell density, as well as collagen and elastic fiber content, in lung tissue from guinea pigs with chronic pulmonary allergic inflammation. Animals received seven inhalations of ovalbumin (1-5 mg/ml; OVA group) or saline (SAL group) during 4 wk. Oral tolerance (OT) was induced by offering ad libitum ovalbumin 2% in sterile drinking water starting with the 1st inhalation (OT1 group) or after the 4th (OT2 group). The ovalbumin-exposed animals presented an increase in baseline and in postchallenge resistance and elastance related to baseline, eosinophil density, and collagen and elastic fiber content in lung tissue compared with controls. Baseline and post-ovalbumin and acetylcholine elastance and resistance, eosinophil density, and collagen and elastic fiber content were attenuated in OT1 and OT2 groups compared with the OVA group. Our results show that inducing oral tolerance attenuates lung tissue mechanics, as well as eosinophilic inflammation and extracellular matrix remodeling induced by chronic inflammation.     

Analysis of chemotaxis when the fraction of responsive cells is small--application to mammalian sperm guidance

The detection of chemotaxis-related changes in the swimming behavior of mammalian spermatozoa in a spatial chemoattractant gradient has hitherto been an intractable problem. The difficulty is that the fraction of responsive cells in the sperm population is very small and that the large majority of the cells, though non-responsive, are motile too. Assessment of the chemotactic effects in a spatial gradient is also very sensitive to the quality of sperm tracking. To overcome these difficulties we propose a new approach, based on the analysis of the distribution of instantaneous directionality angles made by spermatozoa in a spatial gradient versus a no-gradient control. Although the use of this parameter does not allow identification of individual responding cells, it is a reliable measure of directionality, independent of errors in cell tracking caused by cell collisions, track crossings, and track splitting. The analysis identifies bias in the swimming direction of a population relative to the gradient direction. It involves statistical chi(2) tests of the very large sample of measured angles, where the critical chi(2) values are adjusted to the sample size by the bootstrapping procedure. The combination of the newly measured parameter and the special analysis provides a highly sensitive method for the detection of a chemotactic response, even a very small one.     

Optimization of extraction of high-ester pectin from passion fruit peel (Passiflora edulis flavicarpa) with citric acid by using response surface methodology

A central composite design was employed to optimize the extraction of pectin with citric acid. The independent variables were citric acid concentration (0.086–2.91% w/v) and extraction time (17–102 min). The combined effect of these variables on the degree of esterification was investigated. Results have shown that the generated regression models adequately explained the data variation and significantly represented the actual relationship between the independent variables and the responses. Besides that, the citric acid concentration was the most important factor to affect the degree of esterification, as it exerted a significant influence on the dependent variable. Lower citric acid concentration increased the pectin degree of esterification. The surface response showed the relationships between the independent variables, and thus responses were generated. Through this surface, the satisfactory condition of 0.086% w/v citric acid for 60 min was established for extraction of high-ester yellow passion fruit pectin.     

Long-range oxidative damage in duplex DNA: the effect of bulged G in a G–C tract and tandem G/A mispairs

Two series of duplex DNA oligomers were prepared having an anthraquinone derivative (AQ) covalently linked at a 5′-terminus. Irradiation of the AQ at 350 nm leads to injection of an electron hole (radical cation) into the DNA. The radical cation migrates through the DNA causing reaction primarily at G_n sequences. In one series, GA tandem mispairs are inserted between GG steps to assess the effect of the mispair on the transport of the radical cation, reaction (damage) caused by the radical cation at the mispair, and repair of the resulting damage by formamidopyrimidine DNA glycosylase (Fpg). In the second series, a bulged guanine in a G₃C₂ sequence is interposed between the GG steps. These experiments reveal that neither G/A tandem mispairs nor bulged guanines are significant barriers to long-range charge migration in DNA. The radical cation does not cause reaction at guanines in the G/A tandem mispair. Reaction does occur at the bulged guanine, but it is repaired by Fpg.