Use of gas chromatography-olfactometry to identify key odorant compounds in dark chocolate. Comparison of samples before and after conching

After vacuum distillation and liquid-liquid extraction, the volatile fractions of dark chocolates were analyzed by gas chromatography-olfactometry and gas chromatography-mass spectrometry. Aroma extract dilution analysis revealed the presence of 33 potent odorants in the neutral/basic fraction. Three of these had a strong chocolate flavor: 2-methylpropanal, 2-methylbutanal, and 3-methylbutanal. Many others were characterized by cocoa/praline-flavored/nutty/coffee notes: 2,3-dimethylpyrazine, trimethylpyrazine, tetramethylpyrazine, 3(or 2),5-dimethyl-2(or 3)-ethylpyrazine, 3,5(or 6)-diethyl-2-methylpyrazine, and furfurylpyrrole. Comparisons carried out before and after conching indicate that although no new key odorant is synthesized during the heating process, levels of 2-phenyl-5-methyl-2-hexenal, Furaneol, and branched pyrazines are significantly increased while most Strecker aldehydes are lost by evaporation.     

Hemolytic anemia and induction of phase II detoxification enzymes by diprop-1-enyl sulfide in rats: dose-response study

Epidemiological evidence indicates that a high dietary intake of plants of the Allium family, such as garlic and onions, is associated with a decreased risk of cancer in humans. It has been suggested that this chemopreventative effect involves the ability of the aliphatic sulfides derived from these vegetables to increase tissue activities of phase II detoxification enzymes. Several highly effective inducers from garlic have been identified, but most of the previously studied compounds from onion have proved to be only weakly active. In the present study, the inductive activity of another onion-derived sulfide, diprop-1-enyl sulfide, has been investigated. This substance was a potent inducer of phase II enzymes in rats, showing significant effects in the lungs and in the lower part of the gastrointestinal tract, suggesting that diprop-1-enyl sulfide could be a useful chemopreventative agent at these sites. At high dose levels, diprop-1-enyl sulfide caused hemolytic anemia, which may be due to in vivo conversion of the sulfide to active metabolites.     

Elucidation of membrane destabilization in post-mortem muscles using an extracellular paramagnetic agent (Gd-DTPA): an NMR study

The effect of Gd-DTPA on the development in NMR relaxation of skeletal rabbit muscles post-mortem was investigated by dynamic low-field (0.47 T) relaxation measurements from 4 min post-mortem and until 23 h post-mortem. Twelve rabbits were included in the study, and half of the animals were administered 0.2 mmol of Gd-DTPA iv 15 min before sacrifice, while the other half was administered an isotonic salt solution. A significant effect of Gd-DTPA treatment corresponding to a 25% reduction in the T(1) relaxation time was observed. T(2) relaxation was decomposed into two components reflecting intra- and extracellular components (T(2)()alpha and T(2)()beta, respectively), and Gd-DTPA treatment was found to affect both components. However, around 150 min post-mortem a dramatic increase in the difference between control and Gd-DTPA-treated rabbits was observed in the relaxation time of the intracellular water population (T(2)()alpha). Electrical stimulation of the muscles resulted in a significantly earlier onset of the increased effect of Gd-DTPA on the T(2)()alpha population. The increased effect of Gd-DTPA treatment on the T(2)()alpha component is believed to reflect leakage of water from the muscle cells due to membrane destabilization, known to be promoted by electrical stimulation. Accordingly, the present study demonstrates how Gd-DTPA can be used for probing membrane integrity in post-mortem muscles known to be of importance for subsequent water distribution and final water-holding capacity.     

Mycorrhizal colonization and lead distribution in root tissues of Norway spruce seedlings

Non-inoculated spruce seedlings (Picea abies Karst.) and spruce seedlings colonized with Lactarius rufus Fr., Pisolithus tinctorius Coker & Couch or Paxillus involutus Fr. were grown for 35 or 37 weeks in a microcosm system on two types of natural forest humus differing in Pb content. Using X-ray microanalysis, the distribution and content of Pb in the tissues of mycorrhizal and non-mycorrhizal root tips were compared. No significant difference in the Pb contents of root cortex cell walls of non-mycorrhizal and seedlings colonized by Lactarius rufus, Pisolithus tinctorius, or indigenous mycorrhizal fungi (mainly Tylospora sp.) was found. However, in root tips of seedlings colonized by Paxillus involutus, due to a higher binding capacity for cations, the Pb content in cell walls of the root cortex were higher than in non-mycorrhizal roots. Pb contents in cell walls of the cortex of mycorrhizal and non-mycorrhizal roots were 3 times higher in plants growing in humus with a high Pb content than in plants growing in humus with a low Pb content. It is concluded that increasing contents of Pb in the organic matter may lead to an increased loading of the apoplast with Pb. The mycobionts tested in this investigation did not exclude Pb from root tissues.     

The practical use of semiparametric models in field trials

This article examines the practical use of semiparametric models in the analysis of field trials—that is, models with parameterized treatment effects and additive terms derived by a data-driven approach using a locally weighted running line smoother (loess). We discuss graphical methods to identify spatial structure in the data and model selection procedures to choose the degree of smoothing. Once the spatial part of the model has been chosen, hypotheses about the treatment effects may be tested. Semiparametric models are used to analyze two barley field trials exhibiting spatial trends. The first has a single experimental treatment and a row-column design. The second has a split-plot design, and we use a semiparametric model which accounts for the randomization at the different strata of this design. We compare the semiparametric analyses with classical analyses of variance and with alternative spatial models. We find that semiparametric models give a good insight into spatial variation in the field and can improve the precision of parameter estimates.     

Predicting Reversibility of Acidification: The European Sulfur Story

Because of the deleterious effects of acid rain and the need to predict reversibility of acidification, various scientific tools such as modeling, stable isotopes and flux/budget calculations have been used in biogeochemical sulfur (S) research. The aim of this study was to evaluate consistencies and discrepancies between these different tools. While modeling has been seemingly successful in predicting S dynamics in soil solution and stream water by considering inorganic sulfate sorption and desorption only, stable S isotopes indicate that biological S turnover plays a crucial role for the sulfate released to soil solution and stream water. A comparison of budget calculations with soil S pools reveals that inorganic sulfate sorption and desorption are the controlling processes as long as deposition is high (> 15 kg S ha^?1yr^?1) and soils have a high sulfate sorption capacity. This explains the successful model predictions of the last two decades. However, for soils with low sulfate sorption capacity and under low sulfate deposition, organic S seems to be a significant source for stream water sulfate and has to be considered in future modeling.     

Monoclonal Antibody C219 Immunohistochemistry Against P-Glycoprotein: Sequential Analysis and Predictive Ability in Dogs With Lymphoma

In the present study, the prevalence of positive staining for P-glycoprotein using C219 monoclonal antibody was assessed in 58 tissue samples of high-grade lymphoma from dogs before initiation of chemotherapy. Samples were also evaluated at relapse in 22 dogs, at necropsy in 34 dogs, and at all 3 times in 15 dogs. The frequency of positive staining was significantly higher than that found prior to the initiation of chemotherapy at the following times: relapse ( P = .0001), necropsy ( P < .0001), and both relapse and necropsy ( P < .001, sequential data). The frequency of positive staining prior to the initiation of chemotherapy was significantly inversely related to remission ( P < .001) and survival times ( P = .0012). Similarly, when populations below and above the median initial C219 score were compared with respect to remission and survival times, the population with scores greater than the median had significantly lower remission ( P < .001) and survival ( P = .008) times, respectively. The frequency of positive staining determined at relapse was significantly inversely related to the time from relapse to death ( P = .0102). Similarly, when populations below and above the median relapse C219 score were compared with respect to the time from relapse to death, the population with C219 scores greater than the median had a significantly lower time from relapse to death ( P = .006). It appears that this immunohistochemical methodology may be used as a predictor of remission time, survival time, and the time from relapse to death. Additional studies are required to confirm the usefulness of C219 as a true marker of P-glycoprotein and to evaluate P-glycoprotein as a useful prognostic factor in dogs with lymphoma.     

The interactive effects of UV-B and insecticide exposure on tadpole survival, growth and development

Because declines within amphibian populations can seldom be attributed to a single cause, it is important to focus on multiple stressors, both natural and anthropogenic. Variables such as UV-B radiation and chemical contamination can interact with one another in ways that might not be predicted from single-factor studies. We exposed southern leopard frog (Rana sphenocephala) tadpoles to the insecticide carbaryl and varying intensities of UV-B radiation in artificial ponds and examined their effects on survival, size at metamorphosis, and the duration of the larval period. Tadpole survival to metamorphosis was positively influenced by UV-B intensity. Tadpoles in ponds exposed to carbaryl contained over three times more algae and yielded larger metamorphs than control ponds. Although previous laboratory studies have indicated carbaryl becomes more toxic in the presence of UV-B, we did not find such an effect, perhaps because of the protection afforded by dissolved organic carbon within the ponds. Our research emphasizes the importance of conducting field studies to more accurately predict what occurs under a natural setting.     

Oral dermatophilosis in a cat: a case report

An oral lesion in a cat caused by the actinomycete Dermatophilus con-golensis is described. Multiple granulomata were present in biopsy material taken from a tongue lesion. After surgical excision and daily penicillin therapy the condition regressed.
Résumé. Une lésion oralle dans un chat, causée par l'actinomycète Dermatophilus congolensis est décrit. Des granulomes multiples étaient présentes dans la substance de la biopsie, prise de la lésion de la langue. Après l'excision chirurgicale et la thérapie journalière de pénicilline, la condition décroissait.
Zusammenfassung. Man beschreibt eine orale Verletzung in einer Katze, die durch den Strahlenpilz Dermatophilus congolensis , verursachet wird. Die multipelen Granulomata waren im Stoff von der Biopsie, Welches von der Verletzung der Zunge, genommen wird. Der Zustand klang ab, nach der chirurgischen Exicision und nach der täglichen Heilung von Penizillin.