The isoflavones mixture from Trifolium pratense L. protects HCN 1-A neurons from oxidative stress

Oxidative stress-induced neuronal cell death has been implicated in different neurological disorders and neurodegenerative diseases such as Alzheimer's disease and Parkinson's. Using the Alzheimer's disease-associated hydrogen peroxide (H(2)O(2)), we investigated the neuroprotective efficacy of a natural mixture of phytoestrogenic isoflavones (genistein, daidzein, biochanin A and formononetin) from Trifolium pratense L. (Red clover) against oxidative stress-induced cell death in human cortical cell line HCN 1-A maintained in culture. Neuronal viability was determined by MTT or trypan blue test and neuronal integrity by morphological analysis.The results obtained indicate that exposure of HCN 1-A cell cultures to hydrogen peroxide resulted in a concentration-dependent decrease in neuron viability. Concentration of H(2)O(2) ranging from 50 to 200 microg/ml were toxic to these cultures. A 24-hour pretreatment with 0.5, 1 and 2 microg/ml isoflavones extract significantly increased cell survival as evidenced by MTT or trypan blue test and significantly prevented the morphological disruption caused by H(2)O(2) as shown by microscopical inspection, indicating that neurons treated with isoflavones were protected from the cell death induced by H(2)O(2) exposure. These findings imply that the neuroprotective effect of isoflavones extract is partly associated with its antioxidant activity. Further, results of these investigations indicate that although isoflavones extract exert a neuroprotective effect, it do not promoted cortical neuron process outgrowth.     

Preparation,Characterization and Release of Urea from Wheat Gluten Electrospun Membranes

Homogeneous and thin porous membranes composed of oriented fibers were obtained from wheat gluten (WG) using the electrospinning technique. SEM micrographs showed an asymmetric structure and some porosity, which, in addition to a small thickness of 40 μm, are desirable characteristics for the membranes’ potential application in release systems. The membranes were loaded with urea to obtain pastilles. FT-IR and DSC studies confirmed the existence of interactions via hydrogen bonding between urea and WG proteins. The pastilles were studied as prolonged-released systems of urea in water. The release of urea during the first 10 min was very fast; then, the rate of release decreased as it reached equilibrium at 300 min, with a total of ≈98% urea released. TGA analysis showed that the release system obtained is thermally stable up to a temperature of 117 °C. It was concluded that a prolonged-release system of urea could be satisfactorily produced using WG fibers obtained by electrospinning for potential application in agricultural crops.     

No effect of CYP450 and P-glycoprotein on hydroxyurea in vitro metabolism

Our objectives were (1) to study the HU metabolism via human cytochromes and (2) to test if HU is a substrate of P-gp. HU metabolism was investigated by determining the appearance of urea and HU decreasing upon incubation with human liver microsomes. Quantification was determined using HPLC coupled with UV-detection at 449 nm. Our method was linear between 5 and 1000 μ m , precise (coefficients of variation ranging from 1.7 to 9.9%), accurate (97.7–103.9%). The limit of quantification was 7 μ m . The ATPase activity of human P-gp membranes was determined by measuring inorganic phosphate liberation. HU and urea measurements in microsomes were not different between 0 and 60 min whatever HU concentration used from 30 to 300 μ m . The presence of NADPH in the medium has no effect on HU and urea measurements. In the absence of verapamil, the ATPase activity was unaffected by HU at concentrations of 10, 30, 100 and 300 μ m . HU is unlikely to cause clinically relevant drug interactions with the substrates of these enzymes/transporters. However, it will be necessary to validate these in vitro data in patients with sickle cell anemia to evaluate the impact of genetic polymorphisms of these enzymes in a black population.     

The double-stranded RNA-activated protein kinase mediates radiation resistance in mouse embryo fibroblasts through nuclear factor kappaB and Akt activation.

PURPOSE: Activation of the double-stranded RNA-activated protein kinase (PKR) leads to the induction of various pathways including the down-regulation of translation through phosphorylation of the eukaryotic translation initiation factor 2alpha (eIF-2alpha). There have been no reports to date about the role of PKR in radiation sensitivity. EXPERIMENTAL DESIGN: A clonogenic survival assay was used to investigate the sensitivity of PKR mouse embryo fibroblasts (MEF) to radiation therapy. 2-Aminopurine (2-AP), a chemical inhibitor of PKR, was used to inhibit PKR activation. Nuclear factor-kappaB (NF-kappaB) activation was assessed by electrophoretic mobility shift assay (EMSA). Expression of PKR and downstream targets was examined by Western blot analysis and immunofluorescence. RESULTS: Ionizing radiation leads to dose- and time-dependent increases in PKR expression and function that contributes to increased cellular radiation resistance as shown by clonogenic survival and terminal nucleotidyl transferase-mediated nick end labeling (TUNEL) apoptosis assays. Specific inhibition of PKR with the chemical inhibitor 2-AP restores radiation sensitivity. Plasmid transfection of the PKR wild-type (wt) gene into PKR(-/-) MEFs leads to increased radiation resistance. The protective effect of PKR to radiation may be mediated in part through NF-kappaB and Akt because both NF-kappaB and Akt are activated after ionizing radiation in PKR+/+ but not PKR-/- cells. CONCLUSIONS: We suggest a novel role for PKR as a mediator of radiation resistance modulated in part through the protective effects of NF-kappaB and Akt activation. The modification of PKR activity may be a novel strategy in the future to overcome radiation resistance.     

High prevalence of congenital toxoplasmosis in Brazil estimated in a 3-year prospective neonatal screening study

BACKGROUND: A pilot neonatal screening programme revealed a high (approximately 1 per 4800 live births) prevalence of congenital toxoplasmosis (CT) in the State of Rio Grande do Sul, Brazil. The purpose of this paper was to estimate in a larger prospective study the prevalence of CT in the country. METHODS: At the beginning of the study, an in-house indirect enzyme immunoassay (EIA) was used, to be later replaced with a commercial capture IgM fluorometric enzyme immunoassay (FEIA). Both methods detect specific anti-Toxoplasma gondii IgM-class antibodies eluted from dried blood spots. RESULTS: Of the total of 140,914 samples received from all over the country, 47 cases were identified and confirmed as CT. This finding suggests a prevalence of 1 per 3000 live births. Of the 47 patients, only eight (17%) had clinical manifestations: two had intracranial calcifications, four had retinal scars, one had an intracranial calcification and retinal scars, and one had hepatosplenomegaly with lymphoadenopathy. The testing was paid for by the patients' families who volunteered for the study and gave their informed consent. CONCLUSION: The 3-year prospective study using sensitive detection methods, reliable confirmation, and feedback from clinicians showed that CT has an extraordinarily high prevalence in Brazil, in fact the highest ever reported in the world. Although the long-term efficacy of treatment of CT has not been well documented, in view of the availability of reliable diagnostics, confirmation and monitoring, functional logistics, and networking for screening, the insidious nature of the sequelae and the very high prevalence of the disease, neonatal screening for CT should be considered an alternative to no screening at all.     

Availability of vitamin B6 from different food sources

The present study was conducted to investigate the precaecal digestibility of vitamin B6 from selected food sources including eggs, bananas, white cabbage, corn, milk powder, fish, barley, soybeans, brown rice, wheat bran, brewer's yeast, rye and soybean meal. These foods were chosen for their relevance in human and animal nutrition and prepared as they are usually eaten by humans. As confirmed by further investigations the precaecal digestibility is a valuable measure for determining the availability of native B-vitamins. Therefore, pigs were fitted with an end-to-end ileo-rectal anastomosis for digesta passing straight from ileum to rectum, thus avoiding endogenous vitamin synthesis by the colon. Three weeks after surgery the digestibility experiments were carried out during which the animals were fed various experimental diets for a period of 12 days and digesta were collected quantitatively twice a day during the final 5 days of this period. The concentration of vitamin B6 in foods and chyme was determined by high pressure liquid chromatography. Precaecal digestibility of vitamin B6 from all tested food sources ranged from 51 to 91% in the following order: cabbage diet > banana diet > fish diet > milk powder diet > brewer's yeast diet > soybeans diet > soybean meal diet > egg diet/corn diet > barley diet > wheat bran diet > rye diet. Only boiled brown rice had a very low vitamin B6 availability of 16%. The digestibility of vitamin B6 from plant products (excluding the rice) was on average 10% lower when compared with animal products (71 versus 79%).     

Prevalence of Chlamydia trachomatis infection in registered female sex workers in northern Mexico

BACKGROUND: Little is known about the epidemiology of Chlamydia trachomatis infection in female sex workers (FSWs) in Mexico. GOAL: The goal of the study was to determine the prevalence of C trachomatis infection in registered FSWs from northern Mexico and to determine the sociodemographic characteristics associated with the infection. STUDY DESIGN: An enzyme immunoassay was used to test 354 FSWs in three northern Mexican cities for cervical C trachomatis infection. All participants were registered in a government health office. Recruitment was consecutive and voluntary. The association between clinical and sociodemographic characteristics of FSWs and infection was evaluated. RESULTS: The overall prevalence of C trachomatis infection among participants in the three cities was 12.4%. Women of low socioeconomic level and those younger than 25 years were the most frequently infected. Among FSWs in Durango, a higher frequency of C trachomatis infection was found for those who did not use condoms. CONCLUSION: C trachomatis is an important pathogen in the sexually transmitted diseases of registered FSWs in northern Mexico.