Thesis (M.Sc. (Pathobiology))--Mahidol University, 1978.

Thesis (Ph. D.)--University of Wisconsin--Madison, 1983. / Typescript. Vita. Includes bibliographical references.

Thesis--Wisconsin. / Includes bibliographical references (leaves 72-79).

Thesis (Ph.D.) - University of Queensland, 2006. / Includes bibliography.

M.Tech. / Please refer to full text to view abstract

Two studies were conducted using pigs to determine the effects of feeding aflatoxin contaminated diets (AC) with and without various clays on performance, liver function, mineral metabolism and humoral immune response. In the nursery phase of Study I, weanling pigs (n=96) were fed 1% sodium bentonite (SB) with and without AC (922 ppb). In the grower phase, 48 pigs from the nursery phase were continued on SB treatments for 5 wk; AC was discontinued. In the metabolism phase, 24 barrows from the nursery phase were continued on SB and AC. In the nursery phase, average daily gain (ADG), average daily feed intake (ADFI), and feed per gain (F:G) were depressed (P < .05), while serum gammaglutamyltransferase (GGT), alkaline phosphatase levels, and liver weights were increased (P < .05) in pigs fed AC. Feeding SB with AC increased (P < .05) ADG and ADFI, and lowered (P < .05) serum enzyme levels. In the grower phase, performance and serum chemistry did not differ across treatments, but livers of pigs previously fed AC remained larger (P <.01). Pigs fed AC had depressed (P < .05) Na absorption and increased P (P < .05) and Zn (P < .10) absorption compared with controls. SB decreased Na, K and Mg (P < .01), and P and Zn (P < .10) absorption when compared with pigs fed no SB. Pigs fed SB had lower Mg (P < .01) and Zn, Mn, and Na (P < .10) retention when compared to controls. SB decreased Ca absorption and retention when fed with AC and increased absorption when fed with control corn (P < .01). AC and SB treatments had no effect on Cu absorption or retention. Liver mineral levels were not affected in any of the phases. In Study II, two trials were conducted to examine the effectiveness of eight types of clays in reducing the negative effects of AC. [In trial I, seven types of clays (.5%) were fed with AC (500 ppb). ADG and ADFI, and urea N were reduced (P < .05), and serum aspartate aminotransferase and GGT were increased (P < .05) by feeding AC compared with NC. Feeding all the clays with the AC improved ADG and ADFI (P < .05) when compared with pigs fed the AC alone. Some clays were effective in recovering AC altered serum chemistry. In trial II, hydrated Na Al silicate or calcium bentonite (1%) were fed with AC (171 ppb). ADG and ADFI which were reduced for the first 4 wk by feeding AC (P < .05) were improved (P < .05). Humoral immune response was unaffected. In summary, feeding clay with AC can prevent some of the negative effects of aflatoxicosis with minimal influences on mineral metabolism. / Master of Science

Relationships defining conditions conducive for aflatoxin production by Aspergillus f!avus were coupled with a non-equilibrium corn drying model and used to determine constant drying conditions indicating a potential for aflatoxin development. Airflow rates of 0.8 to 16 m³/min/m³ in 18, 20, 22% initial wet-basis moisture content corn were simulated in a drying model at temperatures from 12.7 to 40.6°C and relative humidities from 5 to 95%. The potential for aflatoxin development was expressed in terms of the critical relative humidities at a given temperature and airflow rate. All relative humidities simulated above the critical relative humidity also indicated a potential for aflatoxin development. Typical drying conditions for high airflow, low temperature drying systems found in Virginia were simulated to identify potential aflatoxin problems. A sensitivity analysis evaluated the importance of temperature, time, and relative humidity on the drying conditions indicating a potential for aflatoxin development. The critical relative humidities for aflatoxin development reached high levels when drying was simulated at high airflow rates and/or low initial corn moisture contents. The results of the sensitivity analysis performed indicated that relatively small changes in the criteria for potential aflatoxin development significantly affected the critical relative humidities. The time criterion for initial aflatoxin development used in the model exhibited the greatest sensitivity. Drying data from drying tests performed in November, 1981 were used to validate the corn drying model. / Master of Science

Six lactating Holstein cows received ammonia-treated or untreated aflatoxin-contaminated whole cottonseed (AFWC) or pure AFB₁ with their regular ration. Treatments were: AFWC (5,010 ppb AFB₁), 4 kg/day; the same AFWC treated with 1.5% anhydrous ammonia and 10% water; pure AFB₁ (2.2 mg twice daily) given in capsules; same amount AFB₁ treated with 50% NH₄OH for 26 days at 29°C; same amount ammoniated AFB₁ acidified to final pH of 5.0; same treatment as first except concentration of AFB₁ was 5,511 ppb. Levels of aflatoxin M₁ (AFM₁) in milk were monitored before, during, and after each treatment, and conversion and feed-through ratios were calculated. Feed consumption and milk production were also measured. Mutagenicity of acetone extracts of spray-dried milk was determined using Salmonella/microsomal assay. Ammoniation of AFWC did not reduce concentration of AFB₁ to below FDA action level; however, when the seed was fed, the concentration of AFM₁ in milk was less than FDA action level (0.5 μg/L). Ammoniation of AFB₁ was very effective in reducing levels of AFM₁ in milk of treated cows to less than the FDA action level. The average AFB₁/AFM₁ conversion ratios for the steady-state period of AFM₁ excretion in milk while giving AFWC and AFB₁ was 1.06% and 1.18%, respectively. Ammoniation of AFWC reduced the average AFB₁/AFM₁ ratio to 0.20% during the constant-state period of AFM(,1) excretion in milk. The ration containing AFWC (5,010 or 5,511 ppb AFB₁) caused a highly significant decrease in total milk production and feed consumption; ammoniated AFB₁ decreased total milk production significantly. Complete disappearance of AFM₁ from milk after discontinuing Treatments 1-6 was 120, 48, 95, 72, 96, and 120 h, respectively. Under these laboratory conditions, significance of the results of the Ames test was questionable.

O trabalho objetivou construir um dendograma filogenético das cepas de Aspergillus flavus isoladas de amendoim recém-colhido de quatro regiões de São Paulo (Cafelândia, Jaboticabal, Rosália e Tupã), avaliar o potencial toxigênico e agrupar as cepas quanto à produção de esclerócios. A técnica de AFLP foi utilizada para caracterização genotípica. O potencial aflatoxigênico foi avaliado pelo cultivo das cepas em meio de ágar coco, extração das aflatoxinas por clorofórmio, separação por CCD e quantificação por espectrodenditômetro CS-9000. A indução da produção de esclerócios foi feita pela incubação dos isolados em meio ágar Czapeck-DOX. AFLP gerou 78 fragmentos de 27 pb a 365 pb, sendo 13% não polimórficos. O perfil genotípico revelou 31 haplótipos e de 12 grupos no dendograma. A similaridade entre os isolados variou de 37 a 90 %. O potencial aflatoxigênico revelou 91,7 % de cepas produtoras, com níveis entre 39,27 mg/Kg e 28689,61 mg/Kg para AFB1 e 1,50 mg/Kg a 9781,09 mg/Kg para AFB2. Quanto aos esclerócios, 83,9% das cepas foram produtoras, sendo todas tipo S. / This study aimed to draw a phylogenetic dendogram of Aspergillus flavus strains isolated from fresh harvested peanut from four regions of São Paulo state (Cafelândia, Jaboticabal, Rosália and Tupã), to determine the toxigenic potential and to group them regarding the sclerotia production pattern. The AFLP thecnique was used for genotypic characterization. Aflatoxin production was evaluated by inoculation of fungi in coconut agar, extraction with chloroform, TLC segregation and quantification by spectrophotometer CS-9000. Agar Czapeck-DOX was used to evaluate sclerotia production. AFLP generated 78 fragments varying from 27 pb to 365 pb, 13 % of them were not polymorphic. The genotypic profile showed 31 haplotypes and 12 groups in the dendogram. The similarity among the isolates varied from 37 to 90 %. The aflatoxigenic potential showed 91,7 % of producer strains, with levels between 39,27 mg/Kg and 28689,61 mg/Kg for AFB1 and between 1,50 mg/Kg and 9781,09 mg/Kg for AFB2. Concerning the sclerotia production, 83,9 % of the strains were producers, all were S type.

O objetivo do presente estudo foi avaliar o efeito protetivo da adição de biomassa de Saccharomyces cerevisiae (SC) residual, obtida da fermentação alcoólica de cana e cerveja contra a passagem de aflatoxina M1 para o leite. Para tanto, foi realizado ensaio preliminar in vitro de remoção de AFB1 em solução tampão fosfato pelas diferentes fontes de biomassa de SC (levedura de cana-de-açúcar seca e inativada, LCSI; levedura autolizada, LA; parede celular, PC; e co-produto de cervejaria parcialmente desidratado, CCPD), em temperatura ambiente pelos tempos de contato de 05, 10, 20 e 30 min. O ensaio in vivo foi realizado por meio de 20 vacas multíparas da raça holandesa que foram selecionadas em estágio médio de lactação. O delineamento experimental consistiu em dez tratamentos, um controle negativo, um controle positivo e dois tratamentos (com e sem inclusão de AFB1) para cada uma das quatro diferentes fontes de SC, durante um período de 10 dias para avaliar a produção e a composição do leite, escore de condição corporal e bioquímica sérica. A análise de amostras de leite para quantificação de AFM1 foi realizada empregando-se coluna de imunoafinidade para purificação associada a CLAE acoplada a espectrômetro de massa triplo quadrupolo. O valor do limite de quantificação de AFM1 foi 0,5 &micro;g kg-1. Amostras de ração foram analisadas para quantificação de AFB1 por meio de coluna de imunoafinidade para purificação associada a CLAE. O valor do limite de quantificação de AFB1 foi de 0,5 &micro;g.kg-1. Através do estudo in vitro foi possível observar que a viabilidade celular não é pré requisito para adsorção e que o tempo de incubação não interfere na capacidade de adsorção de AFB1. No estudo in vivo, não foi observado efeito da AFB1 e nem das diferentes fontes de biomassa de SC sobre o escore de condição corporal, produção e composição do leite. A bioquímica sérica (AST, ALT e PT) avaliada foi similar entre os grupos não intoxicados e intoxicado com AFB1. Os tratamentos LA e PC apresentaram maior capacidade de adsorção de AFB1 em vacas leiteiras previamente intoxicadas. / The aim of this study was to evaluate the protective effect of adding residual biomass of Saccharomyces cerevisiae (SC), obtained from the fermentation of sugarcane and beer against aflatoxin M1 passage into milk. Therefore, preliminary in vitro test of AFB1 removal in phosphate buffer solution by SC different biomass sources (inactive dry yeast sugarcane, IDYS, autolyzed yeast, AY; cell wall, CW and co- brewery partially dehydrated product, CBPDP) at room temperature for contact times of 05, 10, 20 and 30 min was performed. The in vivo assays were performed using 20 multiparous Holstein cows that were selected in mid lactation stage. The experimental design consisted of ten treatments, a negative control, a positive control and two treatments (with and without inclusion of AFB1) for each of four different sources of SC, over a period of 10 days to evaluate the milk yield and composition, body condition score and serum biochemistry. Milk sample analysis for quantification of AFM1 were carried out using an immunoaffinity column for purification associated with HPLC coupled to triple quadrupole mass spectrometer. The limit of quantification for AFM1 was 0.5 &micro;g. kg-1. Feed samples were analyzed for AFB1 quantification by immunoaffinity purification column associated with HPLC. The limit of quantification for AFB1 was 0.5 &micro;g.kg-1. For in vitro study it was observed that the cell viability is not prerequisite for adsorption and the incubation time does not interfere with AFB1 adsorption capacity. For in vivo study, there was no effect of AFB1 nor the different SC biomass sources on body condition score, milk yield and composition. There was no significant difference between the originated AFB1 levels from food samples in different days of the experimental period. Serum biochemical (AST, ALT, TP) evaluated was similar between the control group and intoxicated with AFB1. The AY and CW treatments had higher adsorption capacity in dairy cows previously intoxicated.