Modulatory Effect of the Intracellular Content of Lactobacillus casei CRL 431 Against the Aflatoxin B1-Induced Oxidative Stress in Rats.

It has been recognized that lactic acid bacteria exhibit antioxidant properties, which have been mainly endorsed to the intact viable bacteria. However, recent studies have shown that intracellular content (IC) may also be good sources of antioxidative metabolites, which may potentially contribute to oxidative homeostasis in vivo. Hence, the modulatory effect of the intracellular content of Lactobacillus casei CRL 431 (IC431) on aflatoxin B1 (AFB1)-induced oxidative stress in rats was evaluated on the basis of its influence on hepatic lipid peroxidation (LPO), antioxidant status-antioxidant capacity (TAC), catalase (CAT), and glutathione peroxidase (GPx) activities; and on the oxidative stress index (OSi). Results demonstrated that CAT and GPx activities, and TAC, determined in plasma samples, were significantly (P < 0.05) higher in rats treated with AFB1 plus IC431 (3.98 µM/min/mg protein, 1.88 µM/min/mg protein, and 238.7 µM Trolox equivalent, respectively) than AFB1-treated rats (3.47 µM/min/mg protein, 1.46 µM/min/mg protein, and 179.7 µM Trolox equivalent, respectively). Furthermore, plasma and liver tissue samples from rats treated with AFB1 plus IC431 showed significantly (P < 0.05) lower LPO values (52 and 51%, respectively) and OSi (59 and 51%, respectively) than AFB1-treated rats. Hence, our results proved that the intracellular content of Lact. casei CRL 431 contains metabolites that are capable to modulate the antioxidant defense systems in living organism, which may help to ameliorate the damage associated to AFB1-induced oxidative stress.

Screening of Lactobacillus strains for their ability to produce conjugated linoleic acid in milk and to adhere to the intestinal tract.

Conjugated linoleic acid (CLA) has been shown to provide beneficial effects on health; however, the amount consumed in food is far from that required for the desired effects. Thus, increasing the CLA content in dairy foods through milk fermentation with specific lactic acid bacteria (LAB) offers an interesting alternative. Moreover, some LAB may be able to adhere to the intestinal mucosa and produce CLA through endogenous synthesis. Therefore, the objective of this study was to screen LAB isolates for their ability to produce CLA in skim milk and in simulated gastrointestinal conditions. Additionally, the ability of selected CLA-producing LAB to adhere to the intestinal mucosa in a murine model was assessed. Results showed that of 13 strains of Lactobacillus tested, only 4 were able to produce CLA in skim milk supplemented with linoleic acid (13.44 ± 0.78 to 50.9 ± 0.26 µg/mL). Furthermore, these 4 Lactobacillus strains were able to survive and produce CLA in simulated gastrointestinal conditions and to adhere to the intestinal mucosa of Wistar rats after 7 d of oral inoculation with fluorescently labeled bacteria. Accordingly, these 4 Lactobacillus strains may be used to manufacture fermented dairy foods to increase CLA content, and consumption of these fermented milks may result in CLA produced endogenously by these LAB.

Host defences against Giardia lamblia.

Giardia spp. is a protozoan parasite that inhabits the upper small intestine of mammals and other species and is the aetiological agent of giardiasis. It has been demonstrated that nitric oxide, mast cells and dendritic cells are the first line of defence against Giardia. IL-6 and IL-17 play an important role during infection. Several cytokines possess overlapping functions in regulating innate and adaptive immune responses. IgA and CD4(+) T cells are fundamental to the process of Giardia clearance. It has been suggested that CD4(+) T cells play a double role during the anti-Giardia immune response. First, they activate and stimulate the differentiation of B cells to generate Giardia-specific antibodies. Second, they act through a B-cell-independent mechanism that is probably mediated by Th17 cells. Several Giardia proteins that stimulate humoral and cellular immune responses have been described. Variant surface proteins, α-1 giardin, and cyst wall protein 2 can induce host protective responses to future Giardia challenges. The characterization and evaluation of the protective potential of the immunogenic proteins that are associated with Giardia will offer new insights into host-parasite interactions and may aid in the development of an effective vaccine against the parasite.

Phenolic compounds: their journey after intake.

Plant foods are rich in phenolic compounds (PCs) that display multifaceted bioactions in health promotion and disease prevention. To exert their bioactivity, they must be delivered to and absorbed in the gastrointestinal (GI) tract, transported in circulation, and reach the target tissues. During the journey from ingestion to target tissues and final excretion, PCs are subjected to modifications by many factors during their absorption, deposition, metabolism and excretion (ADME) and consequently their bioefficacy may be modified. Consistent with all nutrients in foods, PCs must first be released from the food matrix through mechanical, chemical, and enzymatic forces to facilitate absorption along the GI tract, particularly in the upper small intestine section. Further, glycosylation of PCs directs the route of their absorption with glycones being transported through active transportation and aglycones through passive diffusion. After enteral absorption, the majority of PCs are extensively transformed by the detoxification system in enterocytes and liver for excretion in bile, feces, and urine. The journey of PCs from consumption to excretion appears to be comparable to many synthetic medications, but with some dissimilarities in their fate and bioactivity after phase I and II metabolism. The overall bioavailability of PCs is determined mainly by chemical characteristics, bioaccessibility, and ADME. In this review, factors accounting for variation in PCs bioavailability are discussed because this information is crucial for validation of the health benefits of PCs and their mechanism of action.

Antihypertensive and hypolipidemic effect of milk fermented by specific Lactococcus lactis strains.

The antihypertensive and hypolipidemic effects of milk fermented by specific Lactococcus lactis strains in spontaneously hypertensive rats (SHR) were investigated. The SHR were fed ad libitum milk fermented by Lc. lactis NRRL B-50571, Lc. lactis NRRL B-50572, Captopril (40mg/kg of body weight, Sigma-Aldrich Co., St. Louis, MO) or purified water for 4 wk. Results suggested that Lc. lactis fermented milks presented a significant blood pressure-lowering effect. No significant difference was noted among milk fermented by Lc. lactis NRRL B-50571 and Captopril by the second and third week of treatment. Additionally, milk fermented by Lc. lactis strains modified SHR lipid profiles. Milk fermented by Lc. lactis NRRL B-50571 and B-50572 were able to reduce plasma low-density lipoprotein cholesterol and triglyceride contents. Thus, milk fermented by Lc. lactis strains may be a coadjuvant in the reduction of hypertension and hyperlipidemia and may be used as a functional food for better cardiovascular health.

Hypotensive and heart rate-lowering effects in rats receiving milk fermented by specific Lactococcus lactis strains.

Previous studies have demonstrated that milk fermented by specific Lactococcus lactis strains significantly inhibits the activity of angiotensin I-converting enzyme (ACE). However, the relationship between the ACE inhibitor and its in vivo action has revealed discrepancies. Therefore, the aim of the present study was to investigate the antihypertensive and heart rate (HR)-lowering effect of milk fermented by specific L. lactis in a murine model. Spontaneously hypertensive male rats (271 (SD14) g) were randomised into four treatment groups that were orally administered with milk fermented by L. lactis NRRL B-50 571 or L. lactis NRRL B-50 572 at 35 or 50 mg protein/kg body weight (BW), respectively. Further, two more groups were fed with different solutions as controls: a saline solution as the negative control and Captopril (40 mg/kg BW), a proven ACE inhibitor, as the positive control. Blood pressure and HR were monitored by the tail-cuff method before the treatments and at 2, 4, 6 and 24 h post-oral administration. The results demonstrated that milk fermented by L. lactis NRRL B-50 571 as well as by L. lactis NRRL B-50 572 presented an important systolic and diastolic blood pressure- and HR-lowering effect. Thus, milk fermented by specific L. lactis strains may present potential benefits in the prevention and treatment of CVD associated with hypertension in humans.

Trichuriasis and low-iron status in schoolchildren from Northwest Mexico.

BACKGROUND/OBJECTIVES: The aim of this study was to investigate the association between trichuriasis and iron status in rural schoolchildren from Northwest Mexico. SUBJECTS/METHODS: A total of 73 schoolchildren (37 boys, 36 girls) between the ages of 6 and 10 years were voluntarily recruited from the public primary school of the rural community of El Higueral in Culiacan, Sinaloa (Northwest Mexico) for a cross-sectional study with a longitudinal follow-up of 5 weeks. Data were collected on socioeconomic status, anthropometry, haematological and biochemical indices of iron status, daily iron intake, and prevalence and intensity of trichuriasis. Multiple regression models, independent t-test and paired t-test were used to analyse the association between trichuriasis and iron status in cross-sectional and longitudinal samples, respectively. Adjusted models were tested for linear regression assumptions using residual plots. RESULTS: The mean age of the Trichuris-free and Trichuris-infected groups was 7.7±1.3 and 7.7±1.5 years respectively (P=0.92). The height for age was significantly higher in the Trichuris-free group than the Trichuris-infected group (P=0.02). No differences were found in the socioeconomic variables between the two groups. At baseline, significantly higher concentrations of haemoglobin, haematocrit, blood cell count (RBC) and serum iron were measured in the Trichuris-free group compared with the Trichuris-infected children (P<0.05). An association was found between trichuriasis and haemoglobin adjusted for socioeconomic variables, age and sex. Haemoglobin, RBC and serum ferritin concentrations were significantly increased in the infected children 5 weeks after treatment (P<0.05). CONCLUSIONS: Trichuriasis could be a risk factor for low-iron status in the schoolchildren of Northwest Mexico.

Quality index, consumer acceptability, bioactive compounds, and antioxidant activity of fresh-cut "ataulfo" mangoes (mangifera indica L.) as affected by low-temperature storage.

To measure bioactive compound losses due to minimal processing, mature green fresh-cut mangoes (Mangifera indica L.) cv. "Ataulfo" were subjected to an antioxidant treatment and stored at 5 degrees C during 15 d. Quality index, total phenols, flavonoids, beta-carotene, ascorbic acid, vitamin E, and antioxidant activity were measured during the storage period of fruits. Antioxidant capacity was estimated using ORAC(FL), TEAC, and DPPH assays. The dipping treatments with ascorbic acid (AA) + citric acid (CA) + CaCl2 affected positively quality delaying deterioration of fresh-cut mango as compared with whole fruit. However, dipping treatment affected the consumer preferences of fresh-cut mangoes. The highest vitamin C, beta-carotene, and vitamin E losses were observed after 10 d, being similar in whole and fresh-cut mangoes. The antioxidant activity was not significantly affected by storage time. We conclude that fresh-cut mangoes retained their bioactive compound content during storage and their antioxidant and nutritional properties make them a good source of these compounds.

Identification of T-cell stimulating antigens from Giardia lamblia by using Giardia-specific T-cell hybridomas.

T-cell immune response plays an important role in controlling Giardia lamblia infections. Little is known about the G. lamblia-specific antigens that stimulate a cell-mediated immune response. The aim of the present study was to identify T-cell stimulating G. lamblia antigens. For this purpose, we generated a group of Giardia-specific T-cell hybridomas (2F9, 4D5, 6D10, 8B9, 9B10, 10F7 and 10G5). Hybridomas were screened for reactivity with G. lamblia protein extract by the CTLL bioassay. These T-cell hybridomas did not exhibit any significant activation either in the absence of G. lamblia protein extract or in the presence of irrelevant antigen (hen white egg lysozyme). To further characterize the T-cell hybridomas generated, we selected three hybridomas (10G5, 4D5 and 9B10). Giardia lamblia proteins of 90-110, 65-77 and 40-64 kDa showed T-cell stimulating activity for the hybridomas 10G5, 4D5 and 9B10, respectively, in a concentration-dependent manner. Protein extract obtained from different G. lamblia strains (GS/M-83-H7, WB C6 and a clinical isolate (YJJ)) stimulated all T-cell hybridomas, indicating that T-cell-stimulating antigens are expressed among different G. lamblia strains. In conclusion, we identified T-cell stimulating G. lamblia antigens by using Giardia-specific T-cell hybridomas. To our knowledge, these hybridomas are the first-described T-cell hybridomas specific for G. lamblia.

Impact of Giardia intestinalis on vitamin a status in schoolchildren from northwest Mexico.

We conducted a cross-sectional study in northwest Mexico in order to investigate the association between giardiasis and serum vitamin A in 40 Giardia-infected and 70 Giardia-free schoolchildren who were covered by a regional school breakfast program. There were no significant differences in age, Z-scores for nutritional indices of height for age, weight for age, or weight for height, socioeconomic conditions (employment and education of the parents, household conditions, sanitation facilities, type of drinking water, and family income), and mean daily intakes of vitamin A in the Giardia-free (899 +/- 887 microg) and the Giardia-infected (711 +/- 433 microg) groups. A higher concentration of serum retinol was found in the Giardia-free group than in the Giardia-infected group (0.75 micromol/L versus 0.61 micromol/L, respectively; p < 0.0001). Giardia-infected children were more likely to be vitamin A-deficient than the Giardia-free children (OR = 3.2; 95% CI = 1.2-8.5). Although 95% of the children met the daily-recommended intakes of vitamin A, half of them showed subclinical vitamin A deficiency. It is recognized that vitamin A deficiency is multifactorial and giardiasis was a factor significantly associated with this deficiency in this study. Mexican program developers and policymakers should be aware about the distinction between dietary deficiencies and deficiency diseases when current national program strategies for parasitic control and vitamin A supplementation are redesigned.

Giardia lamblia infection induces different secretory and systemic antibody responses in mice.

The adult mouse model of Giardia lamblia infection serves as an excellent animal model to understand the immunological mechanisms involved in the control and clearance of Giardia infection. Little is known about the G. lamblia-specific antigens that stimulate the humoral immune response in this model of giardiasis. We analysed the secretory and systemic antibody responses to G. lamblia during primary and secondary infection in C3H/HeJ adult mice. Faecal IgA and Serum IgG anti-G. lamblia antibodies were observed at week 2 post-infection. Serum IgG responses remained constant over the next several weeks, whereas faecal IgA titres continued to rise from weeks 2-6 post-infection. Western blot analysis revealed that intestinal IgA and serum IgG antibody responses were directed toward several distinct proteins of G. lamblia. Certain proteins appeared to be recognized by both faecal IgA and serum IgG, whereas other antigens were specific for either the secretory or systemic antibody responses. G. lamblia primary and secondary infections were associated with differences in the antibody recognition pattern. The biochemical and immunological characterization of these antigens will help us to better understand the immunobiology of the G. lamblia-host interaction.

Giardia lamblia: effect of infection with symptomatic and asymptomatic isolates on the growth of gerbils (Meriones unguiculatus).

Gerbils (Meriones unguiculatus) were intragastrically inoculated with axenic Giardia lamblia cultures from symptomatic and asymptomatic children. All isolates were able to colonize the duodenum. However, the colonization capacity of the symptomatic isolates was significantly higher compared to that of the asymptomatic ones. Despite the different colonization capacity of the isolates, the growth curves of infected animals were significantly lower than those of controls. The study demonstrates that acute giardia infections are capable of altering the corporal development of the host. These results may suggest that not only symptomatic, but also asymptomatic giardiasis in children, often unnoticed by parents and clinicians, could be causing a silent detriment in their nutritional status.

[Effect of supplementation with a massive dose of vitamin A in children 6 to 36 months of age]. / Efecto de la suplementación con una dosis masiva de vitamina A en niños de 6 a 36 meses de edad.

OBJECTIVE: To evaluate the impact of a single massive dose of vitamin A on the vitamin and iron status in children of margined urban areas in Hermosillo, Sonora, Mexico. MATERIAL AND METHODS: A total of 60 children received one dose of 100,000 IU (children from 6 to 12 months) and of 200,000 IU (children from 12 to 36 months) of retinol palmitate distributed by the Health Ministry in June, 1994. Serum levels of retinol, carotenoids, iron, transferrin and ferritin were measured at three periods: basal, after two weeks and after three months. RESULTS: The mean for retinol basal values was 0.7 mumol/l, after two weeks it was 0.97 mumol/l (p < 0.001) and after three months it was 0.83 mumol/l (p > 0.05). When basal values were measured, 6.3% of the children showed severe vitamin A deficiency, which disappeared in the periods following the supplement; additionally, 42% showed moderate deficiency which had decreased to less than 7% after three months. No differences were found for serum iron and transferrin levels (p > 0.05), however, ferritin levels increased (p < 0.001) after three months indicating an improvement in iron reserves. CONCLUSIONS: Massive dose distribution may have an important impact on vitamin A and iron status in children.