In-vivo and in-silico toxicity studies of daidzein: an isoflavone from soy.

Daidzein is a naturally occurring compound belonging to the class isoflavones and found in soya beans and other legumes. Acute oral toxicity was performed as per OECD guideline (TG 423) with slight modifications. A repeated dose toxicity study was carried out as per OECD guideline (TG 407). In-silico toxicity such as AMES toxicity, carcinogenicity, mutagenicity, immunotoxicity, hepatotoxicity, skin irritation, reproductive effect, rat and mouse toxicity, LD50, hERG I, II inhibitor and minnow toxicity were predicted using online servers and tools. In an acute oral toxicity study, daidzein did not show any mortality in experimental animals. The No Observed Adverse Effect Level (NOAEL) of daidzein was found to be above 5000 mg/kg. 28 days treatment of diadzein at all doses did not show changes in hematology parameters, clinical biochemistry and kidney function parameters. Gross necropsy or histopathology of important organs showed no signs of toxicity. In-silico predicted parameters also demonstrated risks ranging from low to a nontoxic level. Thus, daidzein was found to be safe in acute and repeated oral dose toxicity studies at all selected doses. In-silico study also indicated that daidzein is safe.

Comparative cardiopulmonary toxicity of exhausts from soy-based biofuels and diesel in healthy and hypertensive rats.

Increased use of renewable energy sources raise concerns about health effects of new emissions. We analyzed relative cardiopulmonary health effects of exhausts from (1) 100% soy biofuel (B100), (2) 20% soy biofuel + 80% low sulfur petroleum diesel (B20), and (3) 100% petroleum diesel (B0) in rats. Normotensive Wistar-Kyoto (WKY) and spontaneously hypertensive rats were exposed to these three exhausts at 0, 50, 150 and 500 µg/m(3), 4 h/day for 2 days or 4 weeks (5 days/week). In addition, WKY rats were exposed for 1 day and responses were analyzed 0 h, 1 day or 4 days later for time-course assessment. Hematological parameters, in vitro platelet aggregation, bronchoalveolar lavage fluid (BALF) markers of pulmonary injury and inflammation, ex vivo aortic ring constriction, heart and aorta mRNA markers of vasoconstriction, thrombosis and atherogenesis were analyzed. The presence of pigmented macrophages in the lung alveoli was clearly evident with all three exhausts without apparent pathology. Overall, exposure to all three exhausts produced only modest effects in most endpoints analyzed in both strains. BALF γ-glutamyl transferase (GGT) activity was the most consistent marker and was increased in both strains, primarily with B0 (B0 > B100 > B20). This increase was associated with only modest increases in BALF neutrophils. Small and very acute increases occurred in aorta mRNA markers of vasoconstriction and thrombosis with B100 but not B0 in WKY rats. Our comparative evaluations show modest cardiovascular and pulmonary effects at low concentrations of all exhausts: B0 causing more pulmonary injury and B100 more acute vascular effects. BALF GGT activity could serve as a sensitive biomarker of inhaled pollutants.

Validação de metodologia QuEChERS-acetato para a análise de multirresíduo de agrotóxicos em amostras de soja e de extrato solúvel de soja utilizando cromatografia líquida de alta eficiência acoplada à espectrometria de massas sequencial / Validation of acetate QuEChERS methodology for pesticides multiresidue analysis in soybean samples and soybean-soluble extract by means of high-performance liquid chromatography coupled to tandem mass spectrometry

Com o aumento da utilização da soja e seus derivados na alimentação humana torna-se importante a avaliação da possibilidade de contaminação desses produtos por resíduos de agrotóxicos. Neste contexto,este estudo efetuou a validação da metodologia QuEChERS-acetato, para análise de 144 resíduos de agrotóxicos em soja e no extrato solúvel de soja por meio de cromatografia líquida acoplada à espectrometria de massas sequencial. Os parâmetros avaliados foram: seletividade (efeito matriz nos dois tipos de amostras), linearidade (faixa de trabalho, significância da regressão e homogeneidade dos resíduos da regressão), exatidão (recuperação), precisão (repetitividade) e limite de detecção e de quantificação.As curvas analíticas apresentaram R2 ≥ 0,95 e r ≥ 0,98 na faixa de trabalho (0,002 a 0,200 μg.mL-1). A exatidão e precisão em dois níveis de fortificação das duas matrizes apresentaram valores de 70 a 120 %de recuperação e CV(%) ≤ 20 %, respectivamente. O limite de detecção e de quantificação apresentou resultados satisfatórios. A metodologia validada possibilitou a determinação de 122 substâncias na matriz soja e 124 na matriz de extrato solúvel de soja...

Contribuições dos estudos de percepção de risco para a análise e o gerenciamento de exposições humanas aagrotóxicos: o caso de Lucas do Rio Verde, MT / Contributions of studies of risk perception for the analysis and management of human exposures to pesticides: the case of Lucas do Rio Verde, MT

Os estudos de Percepção de Risco surgem entre as décadas de 1970 e 1980, visando aomelhor entendimento sobre as motivações que determinam diferentes indivíduos egrupos a reagirem ante um determinado perigo. O principal ponto de partida dessesestudos é conhecer no que diferem as respostas de especialistas e não especialistas(“leigos”) diante de um mesmo problema. Tanto no meio rural quanto no meio urbano,os estudos de percepção de riscos são notadamente importantes por caracterizarsituações que outros tipos de estudo (epidemiológicos, toxicológicos, avaliações derisco) não são capazes de demonstrar. Assim, esta Tese de Doutorado objetivacompreender a importância dos estudos de percepção de riscos para a análise dasexposições humanas a agrotóxicos, a partir de um estudo de caso realizado nomunicípio de Lucas do Rio Verde, MT, importante polo agrícola de produção de soja.Com base nos resultados desse estudo exploratório, buscou-se analisar, de forma crítica,os determinantes da percepção de riscos associados à exposição humana a agrotóxicos,devidamente contextualizados por experiências registradas na literatura de referência. Apartir dos resultados desse estudo procurou-se consolidar a necessidade deincorporarmos os estudos de percepção de riscos, de forma sistemática, à lógica deatenção e vigilância de populações vulneráveis em face do intenso uso de agrotóxicosnos diversos processos de produção agrícola do país, bem como às iniciativas deavaliação e gerenciamento de riscos que tenham nesse tema seu foco...

Risk Perception studies arise between the 1970s and 1980s aiming to understand majormotivations that determine different individuals and groups to act when facing aparticular hazard. The main starting point of these studies is to understand the differingresponses of experts and non-experts ("lay people") facing the same problem. Both inrural and urban areas, risk perception studies are especially important to evincesituations that other types of studies (epidemiological, toxicological, risk assessments)are not able to demonstrate. This DSc. Dissertation aims to understand the importanceof risk perception studies for the analysis of human exposures to pesticides, using asbaseline data from a case study in Lucas do Rio Verde municipality, Mato Grosso State,Central Brazil, an important agricultural region for soybean production. Based on theresults of this exploratory study, we sought to examine, critically, the determinants ofrisk perception associated with human exposure to pesticides, contextualized throughexperiences registered in the reference literature. The results of this study showed theimportance of incorporating risk perception studies, systematically, into health care andhealth surveillance of vulnerable populations living in areas of intensive pesticides usein agriculture, as well as in the scope of risk assessment and management initiativesfocusing on this issue...

Bacteria grown on natural gas prevent soybean meal-induced enteritis in Atlantic salmon.

Dietary inclusion of solvent extracted soybean meal (SBM) is associated with inflammation in the distal intestine of salmonid fish, commonly referred to as SBM-induced enteritis. The enteritis is linked to alcohol soluble components in SBM, but the mechanisms have not been established. Previous studies show that bacterial meal (BM) containing mainly Methylococcus capsulatus grown on natural gas is a suitable protein source for salmonids. The BM is rich in nucleotides, phospholipids, and small peptides that might be beneficial for intestinal homeostasis. In this study, a fish meal (FM)-based control diet (FM diet) and diets with 200 g/kg SBM (SBM diet), 300 g/kg BM (BM diet), and 300 g/kg BM and 200 g/kg SBM (BM-SBM diet) were fed to juvenile Atlantic salmon (Salmo salar) for 80 d. Dietary inclusion of SBM reduced growth (P = 0.007). Inclusion of BM reduced digestibility of protein (P = 0.002) and lipids (P = 0.011) and increased (P < 0.01) the relative weights (g/kg whole body) of total gut, liver, and stomach, and mid and distal intestine. Fish fed the SBM diet developed enteritis, lacked carbonic anhydrase 12 in the brush border of epithelial cells in distal intestine, and had more epithelial cells reacting for proliferating cell nuclear antigen compared with fish fed the other diets. Fish fed the same amount of SBM combined with BM showed no signs of inflammation in the distal intestine. Our results demonstrate that BM grown on natural gas can be used to prevent SBM-induced enteritis in Atlantic salmon.

Histopathological effects of aloe barbadensis and soybean Oil on rat liver / Efectos histopatológicos de aloe barbadensis y aceite de soya en hígado de rata

Aloe Barbadensis, which is a species of Aloe vera, is a popular plant used by the common people and in alternative medicine. This study aimed to analyze the effects of Aloe Barbadensis and soybean oil on liver. For this study Wistar Albino female rats were taken and divided into 3 equal groups; the first group was the control group wherein no treatment was applied, second group in which the dissolved form of A. barbadensis in the soybean oil was applied (25 mg/day), and the third group which only soybean oil was applied (500 mg/day). Biopsy materials were taken from the lobus dexter of the livers of the rats and analyzed with light microscope after the necessary standard processing of histologic slides. Group I demonstrated normal structural characteristics of rat liver. In Group II and Group III, we observed nuclear enlargement, mild increase in chromatin and hydropic degeneration and binucleation in some hepatocytes. Liver histology demonstrated congestion in portal veins, sinusoids and the central veins. Merely in Group III, portal venous congestion and in Group II sinusoidal congestion was evident parenchyma of the liver. Additionally in Group III liver histology demonstrated plasmocyte infiltration in portal areas. Our study showed that using soybean with Aloe Barbadensis is synergystic and increasing each others effects. However we didn't observe mononeuclear infiltrations in Group II, these show antinflammatory effects of Aloe Barbadensis. It is determined that, depending on the used dose of Aloe Barbadensis, the toxic effect can change. If Aloe Barbadensis used very high doses it can have toxic effect on hepatocytes.

Aloe Barbadensis, una especie de Aloe vera, es una planta popular usada por el común de las personas y también en la medicina alternativa. El estudio tuvo como objetivo analizar los efectos del Aloe Barbadensis y aceite de soya en el hígado. Para el estudio se emplearon ratas Wistar hembras Albino y se dividieron en 3 grupos: grupo control I sin tratamiento; grupo II A. barbadensis disuelta en aceite de soja (25 mg / día), y grupo III tratado sólo con aceite de soja (500 mg / día). Fueron extraídas biopsias del lóbulo derecho del hígado de las ratas y luego se analizaron con microscopio de luz. En el grupo I el hígado de las ratas era normal. En los grupos II y III, se observó aumento del tamaño nuclear, leve aumento de la cromatina y degeneración hidrópica y binucleación en algunos hepatocitos. La histología hepática mostró la congestión en las venas porta, sinusoides y las centrales. En el grupo III, la congestión venosa portal y en el Grupo II la congestión sinusoidal fue evidente. Además, el Grupo III reveló infiltración de plasmocitos en áreas portales. El uso de soja con Aloe Barbadensis es sinergista y aumenta cada uno de otros efectos. Infiltraciones mononucleares en el grupo III determinan la reacción inflamatoria. Sin embargo, no observamos infiltración mononuclear en el Grupo II, éste mostró efectos antiinflamatorios de la Aloe Barbadensis. Esto determina que, dependiendo de la dosis usada de Aloe Barbadensis, los efectos tóxicos pueden cambiar. Si es usado en altas dosis Aloe Barbadensis puede producir efectos tóxicos en los hepatocitos.

Análise comparativa de mapas protéicos de amostras de soja convencionais e tolerantes ao herbicida glifosato visando à inocuidade alimentar / Comparative analysis of maps soy protein samples of conventional and tolerant to the herbicide glyphosate for food safety

A soja geneticamente modificada tolerante ao herbicida glifosato tem sido a cultura derivada da engenharia genética mais cultivada atualmente no mundo. Como todo alimento GM a soja tem sido alvo de investigação em relação a sua Biossegurança. Novas estratégias têm sido desenvolvidas e aplicadas neste campo de pesquisa, sendo que métodos rápidos e eficientes de análise proteômica têm sido utilizados para avaliação e monitoramento da segurança e inocuidade alimentar, indicando mudanças no perfil protéico entre variedades convencionais e GM. O objetivo do presente trabalho foi avaliar os mapas protéicos de amostras de soja convencionais e suas derivadas geneticamente modificadas tolerantes ao herbicida glifosato, utilizando técnicas de análise proteômica com ênfase para inocuidade alimentar. Foram utilizadas seis amostras de soja, sendo três convencionais parentais e três derivadas GM, cultivadas entre 2004-2005, em Goiás. O extrato bruto protéico foi submetido à análise por eletroforese unidimensional e bidimensional. A eletroforese 2D, foi realizada utilizando tiras com gradiente de pH de 3-10 e 4-7. As imagens dos mapas protéicos das seis variedades, produzidas em replicatas, foram analisadas pelo software ImageMaster 2D Platinum. O potencial alergênico do extrato protéico bruto foi avaliado para todas as variedades utilizando soro de pacientes alérgicos à soja através de immunoblotting. Nos resultados obtidos observou-se a presença das principais frações protéicas da soja pela eletroforese unidimensional sem alteração significativa entre as amostras parentais e GM, exceto para uma banda de 115 kDa presente nas amostras parentais, mas ausente nas amostras GM. A partir da análise por eletroforese 2D foram identificadas as formas peptídicas correspondentes às frações de β-conglicinina e glicinina bem como diversas outras proteínas encontradas na soja como o inibidor de tripsina e a lipoxigenase. Através do software foi possível observar que um spot apresentou...

Genetically modified soya-tolerant to the herbicide glyphosate culture has been derived from the more cultivated genetic engineering in the world today. As GM soya beans whole food has been investigated in relation to your biosafety. New strategies have been developed and applied research in this field, and fast and efficient methods of analysis proteomics have been used for assessment and monitoring of food security and safety, indicating changes in own protein profile between conventional and GM varieties. The aim of this work was to assess the maps soy protein samples of conventional and genetically modified their derived to the herbicide glyphosate-tolerant, using Proteomics analysis techniques with emphasis on food safety. Six samples were used for conventional soya, three and three derived from GM parental, grown between 2004-2005. The crude protein extract own was subjected to analysis by electrophoresis one-dimensional and two-dimensional. 2D electrophoresis using Strip was held with pH gradient of 3-10 and 4-7. Protein maps images of six varieties produced in replicates have been analysed by the 2D Platinum software ImageMaster. The potential allergenic in crude protein extracts was evaluated for all varieties using allergic patient serum soya by immunoblotting. In the results obtained noted the presence of the main protein fractions of soya by one-dimensional electrophoresis without significant change between parental and GM samples, except for a band of 115 parental kDa present in the sample, but absent in GM samples. From the analysis by 2D electrophoresis peptides forms were identified corresponding to fractions of β-conglicinina and glicinina as well as several other proteins found in soy as trypsin inhibitor and lipoxygenase. Through the software has been possible to observe that a spot presented statistical difference between the samples tested, expressed in greater concentration in the samples GM in parenting. In tests of allergenicity, GM...

SBTX, a new toxic protein distinct from soyatoxin and other toxic soybean [Glycine max] proteins, and its inhibitory effect on Cercospora sojina growth.

SBTX, a novel toxin from soybean, was purified by ammonium sulfate fractionation followed by chromatographic steps DEAE-Cellulose, CM-Sepharose and Superdex 200 HR fast-protein liquid chromatography (FPLC). Lethality of SBTX to mice (LD(50) 5.6 mg/kg) was used as parameter in the purification steps. SBTX is a 44-kDa basic glycoprotein composed of two polypeptide chains (27 and 17 kDa) linked by a disulfide bond. The N-terminal sequences of the 44 and 27kDa chains were identical (ADPTFGFTPLGLSEKANLQIMKAYD), differing from that of 17 kDa (PNPKVFFDMTIGGQSAGRIVMEEYA). SBTX contains high levels of Glx, Ala, Asx, Gly and Lys and showed maximum absorption at 280 nm, epsilon(1cm)(1%) of 6.3, and fluorescence emission in the 290-450 nm range upon excitation at 280nm. The secondary structure content was 35% alpha-helix, 13% beta-strand and beta-sheet, 27% beta-turn, 25% unordered, and 1% aromatic residues. Immunological assays showed that SBTX was related to other toxic proteins, such as soyatoxin and canatoxin, and cross-reacted weekly with soybean trypsin inhibitor and agglutinin, but it was devoid of protease-inhibitory and hemagglutinating activities. The inhibitory effect of SBTX on growth of Cercospora sojina, fungus causing frogeye leaf spot in soybeans, was observed at 50 microg/ml, concentration 112 times lesser than that found to be lethal to mice. This effect on phytopathogenic fungus is a potential attribute for the development of transgenic plants with enhanced resistance to pathogens.

A model to estimate the oestrogen receptor mediated effects from exposure to soy isoflavones in food.

The advantages that regular consumption of a diet containing soy may have on human health have been enshrined in a major health claim that has been approved by the Food and Drug Administration in the USA, regarding potential protection from heart disease by soy. This could have a major influence on the dietary consumption patterns of soy for consumers and lead to the development of soy enriched foods to enable consumers to achieve the benefits thought to be associated with increased soy consumption in a Western diet. If an increase in soy consumption is beneficial to particular disease conditions, there is always the possibility that there will be effects other than those that are desirable. For soy-containing foods there has been concern that the phytoestrogen content of soy, which is composed of several isoflavones, could be a separate health issue, due to the oestrogen-like activity of isoflavones. To address this, a method has been developed to estimate, relative to 17-beta oestradiol, the activity of the common isoflavones present in soy phytoestrogens, based on their binding to and transcriptional activation of the major oestrogen receptor sub-types alpha and beta. Using this approach, the additional oestrogen-like activity that would be expected from inclusion of soy supplemented foodstuffs in a Western diet, can be determined for different sub-populations, who may have different susceptibilities to the potential for the unwanted biological effects occurring with consumption of soy enriched foods. Because of the theoretical nature of this model, and the controversy over the nature of whether some of the oestrogen-like effects of phytoestrogens are adverse, the biological effects of soy isoflavones and their potential for adverse effects in man, is also reviewed. The question that is critical to the long term safe use of foods enriched in soy is, which observed biological effects in animal studies are likely to also occur in man and whether these would have an adverse effect on human health.

Synergistic effects of high-dose soybean intake with iodine deficiency, but not sulfadimethoxine or phenobarbital, on rat thyroid proliferation.

The specificity and dose dependence of the synergistic effects of soybean intake with iodine deficiency on the induction of thyroid proliferation were investigated in female F344 rats. In the first experiment, rats were divided into 6 groups, each consisting of 5 animals, and fed a basal diet containing 20% gluten, an iodine-deficient basal diet alone or an iodine-deficient diet containing 0.2%, 1.0%, 5.0% or 25% defatted soybean for 5 weeks. Soybean feeding synergistically induced thyroid hyperplasias with iodine deficiency only at the 25% dose. In the second experiment, rats were also divided into 6 groups, each consisting of 5 animals, and fed a basal diet, a diet containing 20% defatted soybean, 0.025% sulfadimethoxine (SDM), 20% defatted soybean + 0.025% SDM, 0.05% phenobarbital (PB) or 20% defatted soybean + 0.05% PB for 5 weeks. The SDM treatments significantly (P < 0.05 - 0.01) increased the thyroid weights, but this increase rate was less prominent in the SDM + soybean group than in the SDM alone group. The PB treatment was also associated with a tendency for increase in thyroid weight, but again this was smaller in the PB + soybean group than in the PB alone group. Although the SDM or PB treatments reduced the serum triiodothyronine and thyroxine levels and consequently increased the serum thyroid-stimulating hormone (TSH) levels, the soybean feeding did not affect or rather attenuated these changes. Our results clearly indicate that soybean feeding does not synergistically enhance the effects of SDM or PB on the rat thyroid. Thus it can be concluded that soybean intake specifically interacts with iodine deficiency in induction of thyroid proliferative lesions in rats, only at high doses.

Effects of soya bean flakes and liquorice root extract on enzyme induction and toxicity in B6C3F1 mice.

Both soya bean flakes (SBF) and liquorice root extract (LRE) have previously been reported to have anticarcinogenic properties, which have been thought to be related to an increased activity of specific enzymes responsible for the detoxification of chemical carcinogens. 30- and 90-day studies were conducted in male B6C3F1 mice to determine which, if any, of several detoxification enzymes are induced by SBF or LRE. Mice fed 8 and 25% LRE showed a variety of adverse clinical signs, poor weight gain and 30% mortality. Significant increases in liver:body weight ratios were observed in both the SBF and LRE groups. No significant treatment-related gross autopsy findings were observed in any of the SBF groups. A number of abnormalities were observed in the LRE groups, including lesions of the kidney, liver, spleen and thymus. Liver samples from the 90-day study were analysed for 7-ethoxycoumarin O-deethylase (7-ECOD), benzo[a]pyrene hydroxylase (BPH), superoxide dismutase (SOD), glutathione S-transferase (GST) and UDP-glucuronyl transferase (UDPGT) at 90 days, and at an interim 30-day autopsy. No treatment-related increases were observed for BPH or SOD. Both SBF and LRE induced modest increases in UDPGT activity. SBF induced modest increases in GST activity, but LRE decreased this activity. 7-ECOD activity was significantly increased by LRE and decreased by SBF. Samples from a 30-day study in which both LRE and SBF were administered at various dose levels were examined for UDPGT activity; all dose groups showed decreases in UDPGT activity relative to controls. The results suggest that both SBF and LRE may alter the activities of specific enzymes involved in the detoxification of chemical carcinogens; however, the combination of these two foodstuffs may not produce an additive effect in B6C3F1 mice.

[Fungi N-nitrosamines and mutagens in the extract of the sour corn-soybean cakes from high incidence area of stomach cancer].

Sour corn-soybean cake is the main food of the inhabitants in high incidence area of stomach cancer in Linqu county Shandong province. In the extract of the sour corn-soybean cakes, twelve mycotoxin-producing fungi and 3 N-nitrosamines (NDMA, NDEA, NMEA) were detected and the finding rates of the fungi and the N-nitrosamines were 93.3% and 92.3%, respectively; the concentration of NDMA was 0.4-3.8 ng/ml, NDEA 0.2-8.1 ng/ml, and NMEA 0.3-1.4 ng/ml. The positivity rate of the Ames test (most positive materials were direct mutagens) was 44.12%. The experimental results showed that the extract of the sour corn-soybean cakes containing carcinogenic and mutagenic subjects could have some causal relationship with the incidence of stomach cancer.

Effects of dietary soya bean trypsin inhibitor concentrate on initiation and growth of putative preneoplastic lesions in the pancreas of the rat.

Two studies evaluated the effects of soya bean trypsin inhibitor concentrate (STIC) on early stages of pancreatic carcinogenesis in Wistar rats. In experiment 1, the effects of a 3-month administration of diets containing 3.7% STIC were compared with the effects of administration of diets containing 20% corn oil, in rats pretreated with a single azaserine injection sufficient to initiate putative preneoplastic atypical acinar cell foci. Experiment 2 investigated the capacity of STIC to initiate pancreatic carcinogenesis. Diets containing 3.7% STIC were fed for 4 wk, then diets containing either 5 or 20% corn oil were fed for 3 months. Pancreases were quantitatively evaluated for foci. All groups of azaserine-initiated rats had large numbers of atypical acinar cell foci per cm3 of pancreas. Of these, the group fed 3.7% STIC had pancreatic foci that occupied a significantly greater (P less than 0.01) percentage volume of pancreas than did groups fed 20% corn oil or control diets, which contained 5% corn oil and no added trypsin inhibitor. Very few or no foci were observed in all other groups of either experiment 1 or 2. STIC had a much greater effect on the growth of azaserine-induced lesions than did corn oil. STIC alone did not appear to initiate pancreatic lesions.

Effects of a cholecystokinin receptor antagonist on rat exocrine pancreatic response to raw soya flour.

1 Raw soya flour (RSF) in the diet induces pancreatic hypertrophy and hyperplasia in the rat, changes ascribed to production of a high circulating level of cholecystokinin (CCK) due to inhibition of trypsin in the duodenum. Prolonged ingestion results in pancreatic adenomas and carcinomas. 2 L-364, 718, a potent, highly specific CCK antagonist was used to investigate the short-term role of CCK. 3 In rats fed 50% RSF and L-364, 718 5 mg kg-1 p.o. twice daily for 4 d, there was inhibition of pancreatic hypertrophy and hyperplasia, which is further evidence that peripherally-acting CCK plays a major role in the generation of RSF-mediated changes in the pancreas.

Residue trypsin inhibitor: data needs for risk assessment.

Trypsin inhibitor (TI) occurs naturally in many foods from plants, notably soybean protein products. Heat treatment inactivates TI and improves nutritional quality, but residual TI activity of 5 to 20% remains after typical commercial treatments. Chronic feeding of TI or products that contain TI can inhibit trypsin and chymotrypsin, stimulate their secretion, cause hypertrophy and hyperplasia of the pancreas, and lead to adenomas and carcinomas of the exocrine pancreas. In the rat, TI promotes pancreatic carcinogenesis initiated by azaserine. Data needed for possible risk assessment on TI would include 2-year bioassays from animals treated with TI and fed diets carefully controlled for type and amount of fat (which also promotes pancreatic carcinogenesis). The effects of TI on protein nutrition would have to be considered when identifying the maximum tolerated dose. Major reductions in human dietary TI exposure may not be feasible because of the multiple sources of TI, the substantial promotion by other factors such as fat, and the adverse effects of excessive heat on food products. For risk assessment of TI in a particular food, other promotors and the feasibility of decreasing TI intake must be considered.

Pancreatic growth after partial resection of normal and enlarged pancreas in rats fed soya flour.

Pancreatic growth was studied after partial resection of the normal-sized pancreas in rats fed heated soya flour (HSF) or the enlarged gland in rats fed raw soya flour (RSF). Resection involved the removal of the splenic and gastric segments and in both the normal and enlarged gland this represents a loss of approximately 55% of total pancreatic mass. After partial resection animals were either continued on these preresected diets or changed to the alternative diets. For at least the first 8 days after resection, in all conditions studied, there was a significant increase in DNA synthesis in the pancreas, involving both parenchymal and nonparenchymal cells as shown by autoradiography. The increased cell turnover was not associated with any increase in total DNA content of the gland, indicating that the increase paralleled cell loss in response to injury caused by the surgery. By 160 days after resection of the normal pancreas, RSF feeding caused both hypertrophy and hyperplasia of the remnant, but after partial resection of the enlarged gland, growth was limited to hypertrophy. These results suggest that the pancreas has a limited capacity for additional growth after that initially caused by RSF.

Fate of pancreatic nodules induced by raw soya flour in rats.

We have previously shown that rats fed raw soya flour (RSF) for more than four months develop hyperplastic foci of pancreatic acinar cells, which undergo malignant change if feeding RSF is continued throughout the life of the animals. The tendency to undergo malignant change is augmented by the additional use of a genotoxic carcinogen such as azaserine. The present study has sought to examine the reversibility of the focal neoplastic change in the pancreas. Rats fed RSF for 24 weeks and then given a diet not containing soya flour (NSC) had a normal pancreas when killed after 60 weeks of study. When RSF was fed for only 36 weeks, however, some of the rats developed pancreatic cancer even though the diet had been switched to NSC. Similarly, while azaserine in the dose used in the present study does not produce pancreatic cancer in our strain of Wistar rats, coincident administration of RSF for 12 weeks (but not for six weeks) resulted in progression to pancreatic adenoma. Although change from RSF to NSC after 30 weeks resulted in rapid reduction in pancreatic weight and content of RNA, neoplastic foci persisted and became frankly malignant. We conclude that phenotypic reversion to normal of the RSF diet- and azaserine-treated rat pancreas is only possible if RSF alone is fed continuously for not more than about 24 weeks or six weeks if the rats have been exposed to a pancreatic initiating carcinogen.

Effects of feeding partial and intermittent raw soya flour diets on the rat pancreas.

Continuous administration of a diet consisting of raw soya flour produces pancreatic cancer in rats and sensitises the rat pancreas to the action of genotoxic carcinogens. We have therefore studied the effects of continuous feeding of diets containing lesser amounts of raw soya flour (5%, 25% and 50%) and feeding raw soya flour intermittently (2 days each week). The study has shown that a diet containing as little as 5% raw soya flour stimulates focal proliferation of the pancreatic acinar cells and sensitises to the action of azaserine. Similarly, intermittent feeding of raw soya flour induced focal proliferation of the acinar pancreas and, when 100% raw soya flour diet was fed for 2 days each week, resulted in the development of pancreatic cancer in some of the rats. We conclude that raw soya flour must be excluded from the diets of rats used in toxicological and carcinogenicity studies.

The effect of the long-term feeding of raw soy flour on the pancreas of the mouse and hamster.

The effects of the long-term feeding of mice and hamsters with raw (RSF) or heated (HSF) soy flours were investigated both in the presence and absence of chemical carcinogens. Mice which had been fed RSF for 18 months had enlarged pancreas but only a relatively low incidence of atypical acinar cell nodules (AACN). Mice on either RSF or HSF were also relatively resistant to the carcinogenic effects of azaserine which is known to produce a high incidence of AACN in rats. Hamsters which had been fed RSF for 15 months did not exhibit pancreatic enlargement and had a very low incidence of pancreatic tumors. Although the incidence of tumors in hamsters which had been injected with N-nitrosobis (2-oxopropyl)amine and maintained on HSF was very high (88%), those on RSF had a tumor incidence of less than 10%. Thus, there appears to be a marked difference in the response of the pancreas in different species of animals to the long-term effects of feeding RSF. This should be taken into consideration in evaluating the potential carcinogenicity of the trypsin inhibitors.