Determinants of aflatoxin exposure in young children from Benin and Togo, West Africa: the critical role of weaning.
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BACKGROUND: Dietary exposure to high levels of the fungal toxin, aflatoxin, occurs in West Africa, where long-term crop storage facilitates fungal growth. METHODS: We conducted a cross-sectional study in Benin and Togo to investigate aflatoxin exposure in children around the time of weaning and correlated these data with food consumption, socioeconomic status, agro-ecological zone of residence, and anthropometric measures. Blood samples from 479 children (age 9 months to 5 years) from 16 villages in four agro-ecological zones were assayed for aflatoxin-albumin adducts (AF-alb) as a measure of recent past (2-3 months) exposure. RESULTS: Aflatoxin-albumin adducts were detected in 475/479 (99%) children (geometric mean 32.8 pg/mg, 95% CI: 25.3-42.5). Adduct levels varied markedly across agro-ecological zones with mean levels being approximately four times higher in the central than in the northern region. The AF-alb level increased with age up to 3 years, and within the 1-3 year age group was significantly (P = 0.0001) related to weaning status; weaned children had approximately twofold higher mean AF-alb adduct levels (38 pg AF-lysine equivalents per mg of albumin [pg/mg]) than those receiving a mixture of breast milk and solid foods after adjustment for age, sex, agro-ecological zone, and socioeconomic status. A higher frequency of maize consumption, but not groundnut consumption, by the child in the preceding week was correlated with higher AF-alb adduct level. We previously reported that the prevalence of stunted growth (height for age Z-score HAZ) and being underweight (weight for age Z-score WAZ) were 33% and 29% respectively by World Health Organziation criteria. Children in these two categories had 30-40% higher mean AF-alb levels than the remainder of the children and strong dose- response relationships were observed between AF-alb levels and the extent of stunting and being underweight. CONCLUSIONS: Exposure to this common toxic contaminant of West African food increases markedly following weaning and exposure early in life is associated with reduced growth. These observations reinforce the need for aflatoxin exposure intervention strategies within high-risk countries, possibly targeted specifically at foods used in the post-weaning period. (+info)
The phylogenetic relationship of possible progenitors of the cultivated peanut.
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The cultivated peanut (Arachis hypogaea L.) is an allotetraploid composed of A and B genomes. The phylogenetic relationship among the cultivated peanut, wild diploid, and tetraploid species in the section Arachis was studied based on sequence comparison of stearoyl-ACP desaturase and oleoyl-PC desaturase. The topology of the trees for both fatty acid desaturases displayed two clusters; one cluster with A genome diploid species and the other with B genome diploid species. The two homeologous genes obtained for each of the two fatty acid desaturases from the tetraploid species A. hypogaea and A. monticola were separated into the A and B genome clusters, respectively. The gene phylogenetic trees showed that A. hypogaea is more closely related to the diploid species A. duranensis and A. ipaensis than to the wild tetraploid species A. monticola, suggesting that A. monticola is not a progenitor of the cultivated peanut. In addition, for the stearoyl-ACP desaturase, the A. duranensis sequence was identical with one of the sequences of A. hypogaea and the A. ipaensis sequence was identical with the other. These results support the hypothesis that A. duranensis and A. ipaensis are the most likely diploid progenitors of the cultivated tetraploid A. hypogaea. (+info)
Enhancement of T-cell-depleted bone marrow allografts in the absence of graft-versus-host disease is mediated by CD8+ CD4- and not by CD8- CD4+ thymocytes.
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Transplantation of T-cell-depleted C57BL/6-Nu/Nu ("nude") bone marrow (BM) into C3H/HeJ recipients, conditioned with 8 Gy total body irradiation plus chemotherapy with the myeloablative drug dimethyl myleran, resulted in poor hematopoietic reconstitution 14 days posttransplant, compared with transplantation with T-cell-depleted BM from normal C57BL/6 donors. Hematopoietic reconstitution of "nude" BM could be improved by the addition of (C57BL/6xC3H/HeJ)F1 thymocytes void of graft-versus-host activity. Enhancement of BM allografting by thymocytes is sensitive to low radiation doses (> or = 5.0 Gy) and can be achieved by transplanting the BM 24 hours before the administration of thymocytes. Fractionation of F1 thymocytes by differential agglutination with peanut agglutinin (PNA) and by fluorescence activated cell sorting showed that this hematopoietic enhancing activity is enriched in the unagglutinated (PNA-) thymocyte fraction and is mediated by PNA- CD8+ and not by PNA- CD4+ thymocytes. (+info)
THE EFFECT OF FEEDING TOXIC GROUNDNUT MEAL TO CHICKENS ON OXIDIZED PYRIDINE NUCLEOTIDES LEVELS OF LIVER AND SERUM.
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The extinction coefficient at 260 mmicro (E(260)) of the acid extracts of liver homogenates and sera of chickens were measured during six weeks of feeding with a ration containing 30 per cent groundnut meal contaminated with toxic metabolites of Aspergillus flavus. The data indicated a significant depression of E(260) values of liver extracts following two weeks of consumption of the toxic ration. This lowered value returned to within the normal range after four weeks of feeding and remained at this level until the end of the experiment. The E(260) values of sera were also depressed after two weeks of feeding but persisted at this level throughout the duration of the experiment. (+info)
DETECTION OF UROCANASE IN THE BLOOD OF CHICKENS CHRONICALLY POISONED WITH TOXIC GROUNDNUT MEAL.
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Chickens were fed for up to six weeks a ration containing 30 per cent of toxic groundnut meal and their controls were fed balanced commercial ration for comparable periods. Urocanase activity was determined in the blood and livers of principal and control birds killed after two, four or six weeks on these diets. Urocanase activity was detected in the blood sera of 3 out of the 9 intoxicated birds examined as early as two weeks after the initiation of the feeding trial. By the sixth week, the incidence of urocanase in the serum increased to 5 of 8 intoxicated birds. Liver urocanase concentration was uniform throughout the duration of the experiment when measured in units per gram of hepatic tissue. However, when its activity was expressed on the basis of units per total liver weight, its total activity increased toward the end of the experiment. (+info)
FEEDING OF FERRETS WITH THE RAW MEAT AND LIVER OF CHICKENS CHRONICALLY POISONED WITH TOXIC GROUNDNUT MEAL.
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Chickens were fed a ration containing 30 per cent of toxic groundnut meal for up to six weeks. The concentration of aflatoxin (toxic metabolites of Aspergillus flavus) in the above ration was 3.06 p.p.m. At the end of 2nd, 4th or 6th week the birds were killed. The meat was removed from the bones and put through a meat grinder. The livers of three groups were pooled together. Three control groups of birds kept on commercial pellets were treated similarly. Female ferrets, two years of age, were used in the present study. They were divided into four groups. The first three groups were given for one month meat from chickens fed the toxic ration for 2, 4, and 6 weeks, respectively. Each of these three groups contained one control ferret that was fed with the meat of chickens fed a commercial ration for a similar period of time. One half of the 4th group was fed pooled liver from intoxicated birds and one half was fed liver from control birds. No significant changes in the ferret tissues were observed as a consequence of feeding them with the meat or liver from the chickens chronically poisoned with toxic groundnut meal. (+info)
AN ELECTROPHORETIC INVESTIGATION OF GROUNDNUT PROTEINS: THE STRUCTURE OF ARACHINS A AND B.
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1. The proteins of the groundnut cotyledon have been fractionated and analysed by DEAE-Sephadex chromatography and acrylamide-gel electrophoresis. Seventeen components were detected. 2. A new method is described for the preparation of arachin, using calcium precipitation. The product contains at least 99% of arachin. 3. The theory of acrylamide-gel electrophoresis is developed and applied to the arachin system to predict the molecular weight of one sub-unit of arachin. 4. A variant form of arachin, arachin B, has been discovered. Of 81 nuts, 27 contained only arachin B, 53 contained both arachin A and B, and one contained arachin A only. This is almost certainly a polymorphism of arachin; this is the first example of polymorphism to be reported in plant proteins. 5. A combination of controlled denaturation, electrophoretic analysis, ultracentrifuge and Sephadex filtration data has shown that arachin A contains four different kinds of peptide chains (alpha, beta, gamma and delta). Arachin B contains only beta, gamma and delta chains. 6. The most probable structure for arachin B, mol.wt. 330000 form, is 8 beta, 2 gamma and 2 delta chains, and for arachin A, 4 alpha, 4 beta, 2 gamma and 2 delta chains. Arachin without beta chains was not found. 7. The alpha and beta chains have mol.wts. of about 35000 and the gamma and delta chains of about 10000. 8. Three N-terminal groups were found: the alpha and beta chains both terminate in glycine; the gamma and delta chains terminate in isoleucine and glutamic acid. 9. Arachin contains no carbohydrate. 10. Disulphide bonds are not important in arachin: there are none between the alpha, beta, gamma and delta chains. 11. The amino acid compositions of arachins A and B are very similar. Glutamic acid and aspartic acid residues are exceptionally frequent. (+info)
Groundnut as the commonest foreign body of tracheobronchial tree in winter in Northern India. An analysis of fourteen cases.
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In Northern India, in an institution like ours which receives quite a number of patients from surrounding rural areas, we found groundnut as the most common foreign body of tracheobronchial tree in children particularly in winter months of October to January. This article attempts to address the potential hazard of groundnut inhalation in children. In Northern India, in an institution like ours which receives quite a number of patients from surrounding rural areas, we found groundnut as the most common foreign body of tracheobronchial tree in children particularly in winter months of October to January. This article attempts to address the potential hazard of groundnut inhalation in children. (+info)