Typescript. / Thesis (Ph. D.)--University of Hawaii at Manoa, 1985. / Bibliography: leaves 210-235. / Photocopy. / Microfilm. / xiv, 235 leaves, bound 29 cm

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.

A rapid detection method combining immunomagnetic separation (IMS), PCR and slot blot detection was developed for the detection of Salmonella and Listeria monocytogenes in milk. Bacteria were first isolated and concentrated from phosphate-buffered saline (PBS) or milk by IMS. After extraction from diluted bacteria culture with the extraction buffer, bacterial DNA was subjected to PCR. Slot blot assay was optimized and used to measure PCR products. The lowest level of detection by this method was 40 cfu/ml in PBS or milk for both pathogens. The whole detection procedure could be completed within 7 h. Moreover, this detection method is simple and easy to handle for a large number of samples. Using multiplex PCR (amplification of two different bacterial DNA in the same PCR tube) and slot blot, simultaneous detection of both bacteria was also assessed. The detection sensitivities of 103 cfu/ml for both bacteria were the same as when PCR and slot blot were used for each bacterium separately. The combination of IMS, PCR and slot blot seems to give a highly sensitive and time-efficient procedure, which could be used for routine detection of Salmonella and L. monocytogenes in milk.

Dissertation (PhD)--University of Stellenbosch, 2007. / Bibliography. Also available via the Internet.

Dissertação composta por 02 artigos. / CNPq; Capes / O leite é uma das principais fontes de nutrientes da dieta humana e é um alimento que acompanha o ser humano durante toda a vida, tanto como leite de consumo como através de seus derivados. Entretanto, são inúmeras as formas e os tipos de contaminação que acometem o leite, destacando-se, dentre os contaminantes de ordem química, as aflatoxinas. Dentre os métodos de análise de aflatoxinas em leite e derivados, destaca-se a Cromatografia Líquida de Alta Eficiência (CLAE), principalmente devido a sua versatilidade, rapidez e acuracidade das medidas quantitativas. Entretanto, trata-se de um sistema complexo em que as propriedades dos constituintes da fase móvel são afetadas por mudanças nas condições de processo nas quais são realizados os experimentos. Normalmente as condições de análise por CLAE são determinadas empiricamente, pelo método “tentativa e erro” em que inúmeras tentativas são realizadas sem um estudo mais detalhado do sistema. Diante disso, a primeira etapa deste estudo objetivou a otimização de multirrespostas em CLAE, por meio da seleção das condições ótimas como a composição da fase móvel, sua vazão no sistema cromatográfico e a temperatura da coluna, a fim de identificar, separar e quantificar simultaneamente a aflatoxina M1 (AFM1) e a aflatoxina B1 (AFB1). Para tanto, realizou-se planejamento experimental de misturas para três componentes com restrições combinado com um planejamento fatorial 22 para as variáveis de processo (temperatura da coluna e vazão). Após a definição dos modelos para as variáveis dependentes, foi realizada busca das condições ótimas usando o método simplex sequencial e as funções de desejabilidade de Derringer e Suich. As variáveis avaliadas foram: composição da fase móvel (acetonitrila, metanol e solução aquosa de ácido acético 1%), vazão da fase móvel e temperatura da coluna. Os parâmetros cromatográficos obtidos como respostas foram: tempo e fator de retenção para ambas as aflatoxinas, fator de separação, resolução da coluna e altura dos picos. Após a validação do planejamento, foi realizada a validação analítica do método otimizado através das figuras analíticas de mérito: linearidade, precisão, exatidão e limites de detecção e quantificação. O planejamento realizado foi capaz de produzir modelos confiáveis que possibilitaram a estimativa das melhores condições atendendo aos múltiplos objetivos. Na validação analítica do método cromatográfico, os parâmetros analíticos avaliados ficaram dentro dos intervalos de confiança, podendo o método ser considerado exato e preciso, apresentando limites de quantificação de 0,3 e 0,5 μg L-1 para AFM1 e AFB1, respectivamente e linearidade com R2 > 0,99 para ambas as aflatoxinas. A segunda etapa do estudo objetivou a avaliação da interação entre as AFM1 e AFB1 com proteínas lácteas, tendo em vista que estudos demonstram que aquelas, especialmente a AFM1, localizam-se predominantemente nas frações proteicas. Entretanto, esses estudos não avaliaram a interação entre aflatoxinas e as proteínas do leite, mas apenas baseiam-se na sua quantificação nas frações proteicas do leite. Portanto, buscou-se por meio deste estudo avaliar a possível interação entre as AFM1 e AFB1 com as frações proteicas do leite. Análises por Espectroscopia na região de infravermelho com transformada de Fourier (FTIR) foram realizadas para avaliação de possíveis modificações na estrutura secundária das proteínas lácteas quando fortificadas com as aflatoxinas e Calorimetria Exploratória Diferencial (DSC). Para tanto, preliminarmente foram avaliados os espectros obtidos com padrões de caseína e β-lactoglobulina em solução tampão fosfato-salino (PBS) e em solução modelo, assim como no leite propriamente dito, integral e desnatado. Na segunda etapa, regiões espectrais específicas foram avaliadas por meio de técnicas de deconvolução e curve-fitting. Os resultados indicam que a solução PBS foi mais adequada para o estudo da interação entre as AFB1 e AFM1 e proteínas lácteas avaliadas, β-lactoglobulina e caseína. Foram observadas alterações nas estruturas secundárias e essas sugerem que, embora possivelmente ocorram interações de caráter hidrofílico entre β-lactoglobulina e as aflatoxinas (especialmente com AFM1), ocorram também interações de caráter hidrofóbico (especialmente de AFB1) com os pacotes hidrofóbicos da β-lactoglobulina. Já com a caseína, as alterações promovidas nas estruturas secundárias proteicas foram mais discretas, porém deslocamentos de picos foram observados indicando alterações estruturais da proteína, especialmente na presença de AFB1, o que sugere que ocorram interações químicas entre os componentes avaliados. As alterações espectrais, mais evidentes com a fração β-lactoglobulina, do que com a fração caseína sugerem que, embora a quantificação de aflatoxinas seja comumente superior na fração caseína, não se pode afirmar que por esse motivo ocorram interações mais tangíveis entre aflatoxinas e caseína do que entre aflatoxinas e β-lactoglobulina. Possivelmente a quantificação em maior percentual de aflatoxinas na fração caseína é atribuída ao fato dessa proteína encontrar-se, no leite, em percentual superior às proteínas do soro. Outra hipótese levantada pelo estudo é a possibilidade das aflatoxinas avaliadas encontrarem-se “mascaradas” por estarem conjugadas com a β-lactoglobulina e não sendo, portanto, detectadas pelos métodos analíticos convencionais ocasionando sua subestimação nessa fração. / Milk is one of the main sources of nutrients in the human diet and is a food that accompanies the human being throughout life, both as drinking milk as through its derivatives. However, there are countless forms and types of contamination that affect milk, especially among the contaminants of chemical order, aflatoxins. Among the methods of analysis of aflatoxins in milk and dairy products, the High Performance Liquid Chromatography (HPLC) stands out mainly due to its versatility, speed and accuracy of quantitative measurements. However, it is a complex system in which the properties of the constituents of the mobile phase are affected by changes in process conditions under which the experiments are performed. Typically the HPLC analysis conditions are determined empirically, using the "trial and error" in which numerous attempts are made without a more detailed study of the system. Therefore, the first step of this aimed to optimize multiresponses in HPLC, by selecting the optimal conditions as the mobile phase composition, its flow into the chromatographic system and the column temperature in order to identify, separate and quantify aflatoxin M1 (AFM1) and aflatoxin B1 (AFB1) simultaneously. Therefore, it was carried out experimental a mixture design for three components with restrictions combined with a 22 factorial design to the process variables (flow and column temperature). After defining the models for the dependent variables, a search of the optimum conditions was made using the sequential simplex method and the Derringer and Suich desirability functions. The variables evaluated were: mobile phase composition (acetonitrile, methanol and aqueous solution of acetic acid 1%), the mobile phase flow rate and column temperature. The chromatographic parameters obtained as responses were time and factor of retention for both aflatoxins, separation factor, column resolution and height of the peaks. After the design validation, analytical validation was performed through the analytical figures of merit: linearity, precision, accuracy and limits of detection and quantification. The experimental design carried out was able to produce reliable models that allowed better conditions estimation regarding multiple objectives. In the analytical validation of the chromatographic method, the analytical parameters evaluated were within the confidence interval, the method can be considered accurate and precise showing quantitation limits of 0.3 and 0.5 μg L-1 for AFB1 and AFM1, respectively, and linearity with R2> 0.99 for both aflatoxins. The second stage of the study aimed to evaluate the interaction between the AFB1 and AFM1 with dairy proteins, considering that studies show that those, especially AFM1, are located predominantly in the protein fractions. However, these studies did not evaluate the possibility of interaction between aflatoxins and dairy proteins, but only based on its quantification in the dairy protein fractions. Therefore, we sought through this study to evaluate a possible interaction between AFM1 and AFB1 with dairy protein fractions. Analyzes were performed by Fourier transformation infrared spectroscopy (FTIR) to assess possible changes in the secondary structure of dairy proteins when spiked with aflatoxins and Differential Scanning Calorimetry (DSC). For this purpose, preliminarily the spectra obtained were evaluated with standard casein and β-lactoglobulin in phosphate buffer saline solution (PBS) and a bovine milk model solution as well as in actual milk, whole and skim. In the second step, specific spectra bands were assessed through deconvolution and curve-fitting techniques. The results show that PBS was more suitable for the interaction study between aflatoxins B1 and M1 and the dairy proteins evaluated, β-lactoglobulin and casein. Changes in secondary structures suggest that although possibly occurring interactions with hydrophilic characters between β-lactoglobulin and aflatoxins were observed (especially with AFM1) also occur interactions with hydrophobic character (especially AFB1) with the hydrophobic β-lactoglobulin packages. Already with the casein, the changes introduced in protein secondary structure were more discreet but peak shifts were observed indicating structural changes of the protein, especially in the presence of AFB1, which suggests that chemical interactions occur between the components evaluated. The spectral changes, more evident with the β-lactoglobulin fraction than the casein fraction, suggests that although the quantification of aflatoxins is commonly higher in the casein fraction, it’s not possible to ensure that for this reason occur more tangible interactions between aflatoxins and casein than between aflatoxins and whey proteins (β-lactoglobulin). The greater quantify percentage of aflatoxins in the casein fraction, apparently, is attributed to the fact that this protein is found, in milk, in superior percentage to the whey proteins. Another hypothesis is the possibility of the aflatoxins evaluated are "masked" by being combined with β-lactoglobulin and not, therefore, being detected by conventional analytical methods leading to their underestimation in this fraction. / 5000

No description available.

2008年三鹿三聚氰胺毒奶粉事件震驚國內外，該事件導致六名嬰兒腎結石死亡，逾三萬嬰幼兒從此生活在各種腎疾病的陰霾之下。此後奶產品安全問題尋出不窮，對國內奶產業造成嚴重的負面影響，令消費者對整個國內奶產業信心下降。事實上，在很多奶產品安全的危機中，遭受質疑的企業組織最後均被政府的檢測結果證實是無辜的。在危機中，組織的形象受到威脅，組織需通過不同的方法進行自我辯護。現存的文獻提出，危機溝通策略和組織對責任承擔的態度是兩個影響公眾對組織信心和媒體報導語調的重要因素。組織類型（國有或外資）也會影響公眾對組織的信心和媒體報導語調。過往研究也發現，公眾對組織的信心與媒體報導語調之間存在正相關的聯繫。此研究通過對兩個犯行危機情景的案例研究（2009多美滋危機事件和2010聖元危機事件），目的在於評估危機溝通策略的效用，同時也探討在不同的階段中危機溝通策略、組織責任承擔、組織類型、公眾對組織的信心和媒體報導語調之間的關係。研究成果發現文獻建議之在不同階段的最佳策略和組織責任承擔對公眾對組織的信心和媒體報導語調均無重要影響。然而，使用越少藉口和越多提供信息策略的組織贏得更多公眾信心，從而提升正面媒體報導。研究也發現，外企在第一和第二階段報導更正面，但最後國企反而取得正面的媒體報導。另外，組織類型與階段對組織選取策略與組織責任承擔均有影響。本研究結果顯示西方危機處理理論在低信任度社會如中國等未必適用。研究一方面透過更複雜的情境角度，進一步加深對現有危機傳播文獻的理解，例如引入不同階段的概念來評估危機管理的成效，另一方面也為在低信任社會中的奶產業企業提供有效的危機管理建議。 / Sanlu Melamine-contaminated Milk Scandal, the frequent outbreak of dairy product safety crises had a severe impact on the domestic dairy industry, resulting in a general loss of the consumers' confidence in the entire domestic dairy industry. In fact, in many crises the crisis-ridden organizations were eventually proven innocent by governmental departments. During a crisis, an organization's image is threatened, so that various communicative entities are used to defend this image. Based on the existing literature, this study aims at evaluating the effectiveness of crisis communicative strategies (CCSs) as well as investigating the relationships among CCSs, organization responsibility acceptance, organization ownership type (domestically owned or foreign-invested), confidence in organization and media coverage in different stages during the crisis by comparing the Dumex case in 2009 and the Synutra case in 2010. The results found that the posited optimal CCS in a particular stage and organization responsibility acceptance generally did not have significant effects on confidence in organization or media image coverage. However, the findings revealed that the less excuses and the more information providing strategies were employed, the higher the stakeholders' confidence in organization would be, which in turn significantly increased the positive image coverage. Certain CCSs, i.e., diversion, no response, also showed significant direct effects on media coverage. Moreover, foreign-invested organization appeared to enjoy favorable image coverage in Stage 1 and Stage 2, but domestically owned organization surpassed it in the last stage. Organization ownership type and stages also had significant impacts on the choices of CCSs and degree of organization responsibility acceptance. Stage was also a significant negative predictor of confidence in organization but not for media coverage. This study on one hand revealed that the western crisis management theory might not be accommodative to the low-trust context in mainland China and thus theoretically further the understanding of existing crisis communication literature in a more complex contextual perspective through integrating stages as a significant time factor into the evaluation of crisis management. On the other hand it also pragmatically provides useful suggestions on effective crisis strategic management to dairy corporate in low-trust societies. / Detailed summary in vernacular field only. / Huang, Peiyi. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 159-177). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts also in Chinese; appendixes in Chinese. / ABSTRACT (English version) --- p.i / ABSTRACT (Chinese version) --- p.iii / ACKNOWLEDGEMENT --- p.v / TABLE OF CONTENTS --- p.ix / Chapter 1. --- INTRODUCTION --- p.1 / Chapter 2. --- CONCEPTUALIZATION --- p.9 / Chapter 2.1 --- Crisis Management --- p.9 / Crisis --- p.9 / Crisis Management --- p.11 / Chapter 2.2 --- Outcome: Media Image Coverage --- p.14 / Chapter 2.3 --- Time Factor: Stages --- p.16 / Chapter 2.4 --- Strategic Factors --- p.20 / Crisis Communicative Strategies (CCSs) --- p.20 / Organization Responsibility Acceptance --- p.46 / Chapter 2.5 --- Organizational Factor: Organization Ownership Type --- p.50 / Chapter 2.6 --- Mediator: Confidence in Organization --- p.52 / Chapter 2.7 --- Research Framework, Hypotheses and Research Questions --- p.55 / Chapter 3. --- METHODOLOGY --- p.58 / Chapter 3.1 --- Case Selection --- p.58 / Case --- p.58 / Design --- p.61 / Chapter 3.2 --- Content Analysis --- p.65 / Data Collection --- p.65 / Data Coding --- p.67 / Inter-coder Reliability --- p.70 / Chapter 4. --- RESULTS --- p.71 / Chapter 4.1 --- Basic Sample Information --- p.71 / Chapter 4.2 --- Hypothesis Tests of Two Individual Cases --- p.71 / Case 1 (Dumex) --- p.73 / Chapter tCase 2 (Synutra) --- p.86 / Chapter 4.3 --- The Overall Results of Cases and Research Questions --- p.91 / Media Valance --- p.92 / Research Question 1 --- p.95 / Research Question 2 --- p.99 / Research Question 3 --- p.107 / Chapter 4.4 --- Summary of the Findings --- p.116 / Chapter 5. --- DISCUSSIONS AND IMPLICATIONS --- p.126 / Chapter 5.1 --- Stage as A Complex Concept --- p.126 / Controlling Other Dangers in a Dynamics Crisis --- p.127 / The Role of Governmental Intervention in a Low-trust Society --- p.129 / Chapter 5.2 --- Effects of CCSs on Media Image Coverage inLow-trust Society --- p.132 / Chapter 5.3 --- Mediating Effects of Confidence in Organization --- p.139 / Chapter 5.4 --- Suggestions of Applications of CCSs in Low-trust Society --- p.141 / Chapter 5.5 --- Limit Predictive Power of Organization Responsibility Acceptance --- p.148 / Chapter 5.6 --- Effects of Organization Ownership Type --- p.150 / Chapter 6. --- LIMITATIONS AND FUTURE RESEARCH DIRECTIONS --- p.154 / Chapter 7. --- REFERENCES --- p.159 / Chapter 8. --- APPENDIXES --- p.178

Twelve lactating Holstein dairy cows were randomly divided into four groups of three animals each. Group A served as the control, group B was dosed at 0.05ppm/day of DDE (2,2-bis(P-chlorophenyl-1, 1-dichloroethylene), cows in group C were dosed at 0.1ppm DDE/day, while group D cows were dosed at 1.0ppm DDE/day. DDE was administered in a residue free peanut oil solution for 32-consecutive days. Milk samples were taken daily during the 32 day dosing period and for an additional 32 days after the dosing period. Quantitative analysis of DDE residue in milk fat was determined by using a Tracor MT-220 gas chromatograph with a Tritium electron capture detector. The average increase in DDE milk fat concentration during the dosing period was directly related to intake levels. DDE was the only organochlorine compound detected in the milk fat. The general slope and shape of the curves of milk fat DDE levels were similar for all treatments. The levels of DDE increased rapidly after the onset of dosing. After 15 days of dosing and throughout the remaining 17 days of the dosing period, milk fat DDE increased at a relatively slow rate. The level of milk fat DDE declined rapidly as soon as the DDE residue source was withdrawn. At the end of the 32-day post-dosing period, one cow from each group was slaughtered and samples were taken from muscles, brain, lung, lymph, spleen, kidney fat, heart, gonad, placenta, udder, and kidney for DDE analysis. Considerable DDE was found in the muscle, lymph, kidney fat, and udder tissues.

Thesis (M.S.P.H.)--University of Michigan, 1939.

Thesis (M.S.P.H.)--University of Michigan, 1939.