Minor components in food plants--Note I. Flavonol glycosides from Ullucus tuberosus.

This work deals with the isolation and characterization in Ullucus tuberosus of flavonoids, a class of natural products influencing potentially the taste and nutritional value of the plant food. The three flavonoids, rutin, narcissin and kaempferol 3-O-(2",6"-di-O-alpha-L-rhamnopyranosil)-beta-D-glucopyranoside, isolated, are devoid of taste, but appear to possess health promoting effects.     

Determination by capillary gas liquid chromatography of nitrosamine in partially altered food

The nitrosamines have been extensively studied for their toxicity. Their formation in the foods containing nitrous and nitric derivatives is favoured by the presence of suitable substrata. In the present work have been used column and capillari GL Chromatography for the determination of some nitrosamines in altered foods. The results obtained by applying the suggested procedure to a number of altered samples have been very encouraging.     

Highways are a threat for giant armadillos that underpasses can mitigate

We report 24 records of giant armadillo roadkill on Brazilian highways in the Cerrado, Pantanal and Amazon biomes illustrating that highways are a threat to this species. However, we also documented the species using underpasses, demonstrating that these structures could help to reduce the risk of roadkill for giant armadillos.     

Chagas disease in Mexico

Mexico - the northernmost country of Latin America - has long been thought to have an unusually low prevalence of Chagas disease compared with other Latin American countries. This has seemed unusual because of the large number of vector species and subspecies reported from the country, and the social and ecological conditions that seem to parallel those in other countries where Chagas disease is recognized as a major public health priority. This review seeks to clarify the question, and suggests that the epidemiological, parasitological, and entomological pattern of Chagas disease in Mexico may also parallel that of other endemic regions, but has been masked by poor awareness of the disease both at local and institutional levels.     

Immune humoral response in pigs infected with eggs and posoncospheres of Taenia solium

Due to the importance of cysticercosis in Mexico and Latin America and to the fact that in the last years another mechanism of infection for this disease has been proposed, i.e. through postoncospheres and immunosuppression of the host, we have considered relevant to perform the present work, which consisted in assessing the immune response induced by dexamethasone as well as that produced by parasites in pigs infected with T. solium eggs, or postoncosphere-infected, and in postoncosphere-infected and dexamethasone-treated animals. We used 10 recently weaned pigs, three were used as controls, two of them without the drug and one with it; two were infected with T. solium eggs; five with postoncospheres receiving also dexamethasone three of them. We evaluated the humoral response against parasite antigen using indirect haemagglutination (IH) and ELISA methods. Results of the immune humoral response revealed titres of up to 1:128 in T. solium eggs infected animals, of 1:16 in postoncosphere infected animals, and of 1:32 towards the end of the experiment in postoncosphere plus dexamethasone animals. Absorbance titres with ELISA confirmed these findings. Data obtained by IH show that the antibody titres of the pigs challenged with postoncospheres and postoncospheres plus dexamethasone are positive as compared to the titres obtained in the pigs infected with T. solium eggs. Results from the ELISA confirmed this finding, since, from weeks 14 to 17, the pigs became positive, behaving as those pigs that developed cysticercosis. This is relevant as it indicates that the antiposcosphere antibodies recognized antigens of T. solium larvae.     

Low-dose binary behavior of bystander cell killing after microbeam irradiation of a single cell with focused c(k) x rays

Although conclusive evidence has been obtained for the presence of radiation-induced bystander effects, the mechanisms that trigger and regulate these processes are still largely unknown. The bystander effect may play a critical role in determining the biological effectiveness of low-dose exposures, but questions on how to incorporate it into current models and extrapolate the risks of radiation-induced carcinogenesis are still open. The Gray Cancer Institute soft X-ray microbeam has been used to investigate the dose-response relationship of the bystander effect below 0.5 Gy. The survival response of V79 cells was assessed after the irradiation of a single cell within a population with a submicrometer-size beam of carbon K X rays (278 eV). Above 0.3 Gy, the measured bystander cell killing was in agreement with previously published data; however, a significant increase in the scatter of the data was observed in the low-dose region (<0.3 Gy). The data distribution observed indicates a binary behavior for triggering of the bystander response. According to our hypothesis, the probability of triggering a bystander response increases approximately linearly with the dose delivered to the single selected cell, reaching 100% above about 0.3 Gy. The magnitude of the bystander effect, when triggered, is approximately constant with the dose and results in an overall approximately 10% reduction in survival in our system. This suggests that the event that triggers the emission of the bystander signal by the hit cell is an all-or-nothing process. Extrapolation of the data indicates that when a single fast electron traverses a V79 cell, there is a probability of approximately 0.3% that the cell will emit the bystander signal. The data presented in this paper have also been analyzed statistically to test the possibility that complex DNA double-strand breaks may be the initial critical event.     

Misfolding pathways of the prion protein probed by molecular dynamics simulations

Although the cellular monomeric form of the benign prion protein is now well characterized, a model for the monomer of the misfolded conformation (PrP(Sc)) remains elusive. PrP(Sc) quickly aggregates into highly insoluble fibrils making experimental structural characterization very difficult. The tendency to aggregation of PrP(Sc) in aqueous solution implies that the monomer fold must be hydrophobic. Here, by using molecular dynamics simulations, we have studied the cellular mouse prion protein and its D178N pathogenic mutant immersed in a hydrophobic environment (solution of CCl4), to reveal conformational changes and/or local structural weaknesses of the prion protein fold in unfavorable structural and thermodynamic conditions. Simulations in water have been also performed. Although observing in general a rather limited conformation activity in the nanosecond timescale, we have detected a significant weakening of the antiparallel beta-sheet of the D178N mutant in CCl4 and to a less extent in water. No weakening is observed for the native prion protein. The increase of beta-structure in the monomer, recently claimed as evidence for misfolding to PrP(Sc), has been also observed in this study irrespective of the thermodynamic or structural conditions, showing that this behavior is very likely an intrinsic characteristic of the prion protein fold.     

Pyridostigmine enhances even if it does not normalize the growth hormone responses to growth hormone-releasing hormone in patients with Cushing's disease.

Subjects with Cushing's disease have diminished growth hormone (GH) response to growth hormone-releasing hormone (GHRH). The aim of our study was to investigate the underlying mechanism of this diminished GH response in these patients using pyridostigmine (PD), an acetylcholinesterase inhibitor, which is reported to increase GH secretion by reducing somatostatin tone. Eight subjects with untreated Cushing's disease (caused by a pituitary adenoma) and 6 control subjects received GHRH 100 micrograms in 1 ml of saline, as intravenous bolus injection 60 min after (1) placebo (2 tablets, p.o.) or (2) PD (120 mg, p.o.). After GHRH plus placebo, the GH peak (mean +/- SEM) was significantly lower in subjects with Cushing's disease (2.4 +/- 0.5 micrograms/l) compared to control subjects (25.1 +/- 1.8 micrograms/l, p less than 0.05). After GHRH plus PD, the GH peak was significantly enhanced both in subjects with Cushing's disease (7.1 +/- 2.3 micrograms/l, p less than 0.05) and in control subjects (42.3 +/- 4.3 micrograms/l, p less than 0.05). In patients with Cushing's disease, the GH response to GHRH plus PD was lower with respect to the GH response to GHRH alone in normal subjects. We conclude that hypercortisolism may cause a decrease in central cholinergic tone which is in turn hypothesized to be responsible of an enhanced somatostatin release from the hypothalamus. However, other metabolic or central nervous system alterations may act synergistically with hypercortisolism in causing GH inhibition in patients with Cushing's disease.     

The effect of exposure to radiofrequency LTE signal and coexposure to mitomycin-C in Chinese hamster lung fibroblast V79 cells

This study aims to investigate the cellular effects of radiofrequency exposure, 1950 MHz, long-term evolution (LTE) signal, administered alone and in combination with mitomycin-C (MMC), a well-known cytotoxic agent. Chinese hamster lung fibroblast (V79) cells were exposed/sham exposed in a waveguide-based system under strictly controlled conditions of both electromagnetic and environmental parameters, at specific absorption rate (SAR) of 0.3 and 1.25 W/kg. Chromosomal damage (micronuclei formation), oxidative stress (reactive oxygen species [ROS] formation), and cell cycle progression were analyzed after exposure and coexposure. No differences between exposed samples and sham-controls were detected following radiofrequency exposure alone, for all the experimental conditions tested and biological endpoints investigated. When radiofrequency exposure was followed by MMC treatment, 3 h pre-exposure did not modify MMC-induced micronuclei. Pre-exposure of 20 h at 0.3 W/kg did not modify the number of micronuclei induced by MMC, while 1.25 W/kg resulted in a significant reduction of MMC-induced damage. Absence of effects was also detected when CW was used, at both SAR levels. MMC-induced ROS formation resulted significantly decreased at both SAR levels investigated, while cell proliferation and cell cycle progression were not affected by coexposures. The results here reported provide no evidence of direct effects of 1950 MHz, LTE signal. Moreover, they further support our previous findings on the capability of radiofrequency pre-exposure to induce protection from a subsequent toxic treatment, and the key role of the modulated signals and the experimental conditions adopted in eliciting the effect.