Orally Administered Fumonisins Affect Porcine Red Cell Membrane Sodium Pump Activity and Lipid Profile Without Apparent Oxidative Damage.

Weaned piglets (n = 3 × 6) were fed 0, 15 and 30 mg/kg diet fumonisin (FB1, FB2 and FB3, i.e., FBs, a sphinganine analogue mycotoxin), from the age of 35 days for 21 days, to assess mycotoxin induced, dose-dependent changes in the red cells' membrane. Ouabain sensitive Na+/K+ ATPase activity was determined from lysed red cell membranes, membrane fatty acid (FA) profile was analysed, as well as antioxidant and lipid peroxidation endpoints. Final body weight was higher in the 30 mg/kg group (vs. control), even besides identical cumulative feed intake. After 3 weeks, there was a difference between control and the 30 mg/kg group in red cell membrane sodium pump activity; this change was dose-dependent (sig.: 0.036; R2 = 0.58). Membrane FA profile was strongly saturated with non-systematic inter-group differences; pooled data provided negative correlation with sodium pump activity (all individual membrane n6 FAs). Intracellular antioxidants (reduced glutathione and glutathione peroxidase) and lipid peroxidation indicators (conj. dienes, trienes and malondialdehyde) were non-responsive. We suppose a ceramide synthesis inhibitor (FB1) effect exerted onto the cell membrane, proven to be toxin dose-dependent and increasing sodium pump activity, with only indirect FA compositional correlations and lack of lipid peroxidation.

Occurrence and Human-Health Impacts of Mycotoxins in Somalia.

Mycotoxins are secondary metabolites produced by various molds that contaminate many staple foods and cause a broad range of detrimental health effects in animals and humans through chronic exposure or acute toxicity. As such, the worldwide contamination of food and feed with mycotoxins is a significant problem, especially in sub-Saharan Africa. In this study, mycotoxin occurrence in staple foods consumed in Somalia was determined. A total of 140 samples (42 maize, 40 sorghum, and 58 wheat) were collected from a number of markets in Mogadishu, Somalia, and analyzed by a UPLC-MS/MS multimycotoxin method that could detect 77 toxins. All of the maize samples tested contained eight or more mycotoxins, with aflatoxin B1 (AFB1) and fumonisin B1 (FB1) levels reaching up to 908 and 17 322 µg/kg, respectively, greatly exceeding the European Union limits and guidance values. The average probable daily intake of fumonisins (FB1 and FB2) was 16.70 µg per kilogram of body weight (kg bw) per day, representing 835% of the recommended provisional maximum tolerable daily intake value of 2 µg/(kg bw)/day. A risk characterization revealed a mean national margin of exposure of 0.62 for AFB1 with an associated risk of developing primary liver cancer estimated at 75 cancers per year per 100 000 people for white-maize consumption alone. The results clearly indicate that aflatoxin and fumonisin exposure is a major public-health concern and that risk-management actions require prioritization in Somalia.

Dose and Exposure Time-Dependent Renal and Hepatic Effects of Intraperitoneally Administered Fumonisin B1 in Rats.

Male Wistar rats were treated intraperitoneally (i.p.) with fumonisin B1 (FB1; 0, 20, 50 and 100 mg/kg dietary dose equivalent) for 5 and 10 days (n = 24⁻24 in each setting) to gain dose- and time-dependent effects on antioxidant status and oxidative stress response, clinical chemical endpoints and liver, kidney and lung histopathology and lymphocyte damage (genotoxicity). FB1 decreased feed intake, body weight gain and absolute liver weight, irrespective of the toxin dose. Relative kidney weight increased in the 10-day setting. Linear dose response was found for plasma aspartate aminotransferase, alanine aminotransferase, total cholesterol, urea and creatinine, and exposure time-dependence for plasma creatinine level. The latter was coupled with renal histopathological findings, tubular degeneration and necrosis and the detachment of tubular epithelial cells. The pronounced antioxidant response (reduced glutathione accretion, increasing glutathione peroxidase activity) referred to renal cortical response (5⁻10 days exposure at 50⁻100 ppm FB1). Hepatic alterations were moderate, referring to initial phase lipid peroxidation (exposure time dependent difference of conjugated diene and triene concentrations), and slight functional disturbance (↑ total cholesterol). Lymphocyte DNA damage was moderate, supporting a mild genotoxic effect of FB1.

Toxicological effects of fumonisin B1 in combination with other Fusarium toxins.

Fusarium is a fungal genus spread worldwide commonly associated to the production of several mycotoxins, where fumonisins (FBs) are of major importance due to its prevalence. Since mycotoxins have been reported to cause deleterious effects on mammalians, including carcinogenic, neurotoxic, estrogenic, and immune-suppressive, many countries had established regulations on the tolerated concentrations of such substances in foods and animal feed. Even though many mycotoxins - especially fusariotoxins - are concomitantly found in a single matrix, there is no regulation on co-occurrence levels. This is possibly a result of the lack of data in the literature on the toxicological interactions between different mycotoxins. Considering this, it is of utmost importance to gather what is currently known about the combination of FBs, considered to be the most ubiquitous mycotoxins, with other frequently reported fusariotoxins, such as zearalenone (ZEA), deoxynivalenol (DON), nivalenol (NIV), T-2 toxin (T-2), and other emerging mycotoxins. This paper gives an overview about the toxic effects of fusariotoxins individually and combined to FB1, also gathering the mechanisms and probable interactions between them. This important information may help to develop regulations covering multi-mycotoxins contamination, a growing concern of current days.

Creatine kinase and ATPase activities in piglets fed a fungal mycotoxin co-contaminated diet: Consequences in the pathogenesis of subclinical intoxication.

Creatine kinase (CK) activity, through the creatine-kinase-phosphocreatine (CK/PCr) system, provides a temporal and spatial energy buffer to maintain cellular energetic homeostasis, being responsible to provide adenosine triphosphate (ATP) to the proper function of ATPases enzymes, such as the sodium-potassium (Na+, K+-ATPase) and hydrogen (H+-ATPase) pumps. Thus, the aim of this study was to evaluate the involvement of CK/PCr system in the impairment of energetic homeostasis in piglets fed with a diet co-contaminated with mycotoxins, as well as the effects on ATPases enzymes. Animals were randomly divided in two groups (eight repetitions with two animals each): CON (basal diet) and MYC (mycotoxin diet; 9300 µg/kg of aflatoxins and 8000 µg/kg of fumonisins) which were feed during 15 days. Piglets that received a diet containing 300 µg/kg of aflatoxins and 8000 µg/kg of fumonisins (MYC group) presented lower body weight on days 10 and 15 of experiment when compared to control (CON group). Serum CK activity was lower on days 5, 10 and 15 of experiment in the MYC group. The same occurred for serum Na+, K+-ATPase and H+-ATPase activities on days 10 and 15 when compared to CON group. Moreover, serum calcium levels were superior on day 15 of experiment in the MYC group, while serum potassium and sodium levels were lower in comparison to CON group. Based on these evidences, a diet co-contaminated by aflatoxins and fumonisins inhibits serum CK activity, impairing the energetic homeostasis. This inhibition alters the activities of ATPases (Na+, K+-ATPase and H+-ATPase), contributing to the imbalance of Na+, K+ and Ca+ ionic levels. In summary, the cascade of alterations contributes directly to disease pathogenesis of piglets intoxicated by mycotoxins.

Induction of an altered lipid phenotype by two cancer promoting treatments in rat liver.

Changes in lipid metabolism have been associated with tumor promotion in rat liver. Similarities and differences of lipid parameters were investigated using the mycotoxin fumonisin B1 (FB1) and the 2-acetylaminofluorene/partial hepatectomy (AAF/PH) treatments as cancer promoters in rat liver. A typical lipid phenotype was observed, including increased membranal phosphatidylethanolamine (PE) and cholesterol content, increased levels of C16:0 and monounsaturated fatty acids in PE and phosphatidylcholine (PC), as well as a decrease in C18:0 and long-chained polyunsaturated fatty acids in the PC fraction. The observed lipid changes, which likely resulted in changes in membrane structure and fluidity, may represent a growth stimulus exerted by the cancer promoters that could provide initiated cells with a selective growth advantage. This study provided insight into complex lipid profiles induced by two different cancer promoting treatments and their potential role in the development of hepatocyte nodules, which can be used to identify targets for the development of chemopreventive strategies against cancer promotion in the liver.

In vivo formation of N-acyl-fumonisin B1.

Fumonisins are fungal toxins found in corn and in corn-based foods. Fumonisin B1 (FB1) is the most common and is toxic to animals, causes cancer in rodents, and is a suspected risk factor for cancer and birth defects in humans. The hydrolyzed form of FB1 (HFB1) also occurs in foods and is metabolized by rats to compounds collectively known as N-acyl-HFB1 (also known as N-acyl-AP1). N-acyl-HFB1 is structurally similar to ceramides, metabolites which have important structural and signaling functions in cells. FB1 is N-acylated in vitro to ceramide-like metabolites which, like FB1, are cytotoxic. However, metabolism of FB1 and inhibition of ceramide synthase by its metabolites in vivo has not been demonstrated. Male rats were dosed ip with 0.5, 1, or 2 mg/kg body weight FB1 on five consecutive days and the liver and kidney thereafter processed for chemical analysis. N-acyl derivatives of fumonisin B1 were identified for the first time in these principal target organs of FB1 in rats, at levels up to 0.4 nmol/g tissue using mass spectrometry. The N-acyl chain length of the metabolites varied in a tissue-dependent manner with C16 derivatives predominating in the kidney and C24 derivatives being prevalent in the liver. The toxicological significance of N-acyl-fumonisins is not known and warrants investigation.

Protective role of probiotic lactic acid bacteria against dietary fumonisin B1-induced toxicity and DNA-fragmentation in sprague-dawley rats.

The genus Fusarium, especially F. verticillioides and F. proliferatum, has been found in several agricultural products worldwide, especially in maize. Regardless the occurrence of symptoms, the presence of Fusarium in maize constitutes an imminent risk due to its ability to produce fumonisins, mycotoxins with proven carcinogenic effect on rats, swine, and equines and already classified as possible carcinogens to humans. The toxicity of incremental levels of fumonisin B1 (FB1), that is, 50, 100, and 200 mg FB1/kg diet, and the role of Lactobacillus delbrueckii subsp. lactis DSM 20076 (LL) and Pediococcus acidilactici NNRL B-5627 (PA) supplementation in counteracting the FB1 effects in intoxicated rats were monitored over a period of 4 weeks. Effects on the feed intake and body weight gain were noticed. A significant (p ≤ 0.05) increase in the level of liver and kidney functions markers and DNA fragmentation was also noticed in rat groups T100 and T200. The lactic acid bacteria (LAB) supplementation could bring back the normal serum biochemical parameters in rats fed on fumonisin B1-contaminated diets (T50 and T100) compared to FB1-treated groups. In rats of high-dosage dietary groups supplemented with LAB (T200-LL and T200-PA), the supplementation reduced the serum activity levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and creatinine by 11.3, 11.9, 32, and 20%, respectively. DNA fragmentations were observed in the rat group treated with 200 mg FB1 after 3 weeks, while fragmentation was noticed in treated groups with 100 and 200 mg FB1 after 4 weeks. No DNA fragmentation was apparent in FB1-treated rats co-administered the LL or PA strain. These results suggest that in male rats consuming diets containing FB1, there is a time- and dose-dependent increase in serum enzyme activities and DNA lesions. Moreover, Lb. delbrueckii subsp. lactis (LL) and P. acidilactici (PA) strains have a protective effect against antigenotoxicity and precancerous lesions.

Effects of fumonisin B1 alone and combined with deoxynivalenol or zearalenone on porcine granulosa cell proliferation and steroid production.

Fumonisin B1 (FB1) is a Fusarium mycotoxin frequently occurring in corn in combination with deoxynivalenol (DON) and zearalenone. The aim of this study was to determine if FB1, alone and combined with DON or α-zearalenol (ZEA), zearalenone major active metabolite, can affect granulosa cell proliferation, steroid production, and gene expression in swine. Porcine granulosa cells were cultured for 2 days in serum-containing medium followed by 1 or 2 days in serum-free medium with or without added treatments. Fumonisin B1 had inhibitory effects on granulosa cell proliferation. Deoxynivalenol strongly inhibited cell growth, and no significant difference was detected in combination with FB1. α-Zearalenol showed a stimulatory effect on granulosa cell numbers even in combination with FB1. Regarding steroid production, FB1 increased progesterone production, and FB1 had no effect on estradiol production. Deoxynivalenol strongly inhibited progesterone and estradiol production, and FB1 had no significant effect on this response. α-Zearalenol increased progesterone production, and its combination with FB1 produced additive effects. α-Zearalenol had no effect on estradiol production, whereas it decreased estradiol production when co-treated with FB1. Fumonisin B1 was found to decrease CYP11A1 messenger RNA abundance, and the stimulatory effect of FB1 on progesterone production was found to be not dependent on 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity suggesting that FB1 increases progesterone production through a different mechanism. The results show that these Fusarium mycotoxins can influence porcine granulosa cell proliferation and steroid production, thereby demonstrating their potential reproductive effects on swine.

A food photograph series for identifying portion sizes of culturally specific dishes in rural areas with high incidence of oesophageal cancer.

Rural areas of the Eastern Cape (EC) Province, South Africa have a high incidence of squamous cell oesophageal cancer (OC) and exposure to mycotoxin fumonisin has been associated with increased OC risk. However, to assess exposure to fumonisin in Xhosas--having maize as a staple food--it is necessary to determine the amount of maize consumed per day. A maize-specific food frequency questionnaire (M-FFQ) has recently been developed. This study developed a food photograph (FP) series to improve portion size estimation of maize dishes. Two sets of photographs were developed to be used alongside the validated M-FFQ. The photographs were designed to assist quantification of intakes (portion size photographs) and to facilitate estimation of maize amounts in various combined dishes (ratio photographs) using data from 24 h recalls (n = 159), dishing-up sessions (n = 35), focus group discussions (FGD) (n = 56) and published literature. Five villages in two rural isiXhosa-speaking areas of the EC Province, known to have a high incidence of OC, were randomly selected. Women between the ages of 18-55 years were recruited by snowball sampling and invited to participate. The FP series comprised three portion size photographs (S, M, L) of 21 maize dishes and three ratio photographs of nine combined maize-based dishes. A culturally specific FP series was designed to improve portion size estimation when reporting dietary intake using a newly developed M-FFQ.

Fumonisin FB1 treatment acts synergistically with methyl donor deficiency during rat pregnancy to produce alterations of H3- and H4-histone methylation patterns in fetuses.

SCOPE: Prenatal folate and methyl donor malnutrition lead to epigenetic alterations that could enhance susceptibility to disease. Methyl-deficient diet (MDD) and fumonisin FB1 are risk factors for neural tube defects and cancers. Evidence indicates that FB1 impairs folate metabolism. METHODS AND RESULTS: Folate receptors and four heterochromatin markers were investigated in rat fetuses liver derived from dams exposed to MDD and/or FB1 administered at a dose twice higher than the provisional maximum tolerable daily intake (PMTDI = 2 µg/kg/day). Even though folate receptors transcription seemed up-regulated by methyl depletion regardless of FB1 treatment, combined MDD/FB1 exposure might reverse this up-regulation since folate receptors transcripts were lower in the MDD/FB1 versus MDD group. Methyl depletion decreased H4K20me3. Combined MDD/FB1 decreased H4K20me3 even more and increased H3K9me3. The elevated H3K9me3 can be viewed as a defense mechanism inciting the cell to resist heterochromatin disorganization. H3R2me2 and H4K16Ac varied according to this mechanism even though statistical significance was not consistent. CONCLUSION: Considering that humans are exposed to FB1 levels above the PMTDI, this study is relevant because it suggests that low doses of FB1 interact with MDD thus contributing to disrupt the epigenetic landscape.

Calcium montmorillonite clay reduces urinary biomarkers of fumonisin B1 exposure in rats and humans.

Fumonisin B1 (FB1) is often a co-contaminant with aflatoxin (AF) in grains and may enhance AF's carcinogenicity by acting as a cancer promoter. Calcium montmorillonite (i.e. NovaSil, NS) is a possible dietary intervention to help decrease chronic aflatoxin exposure where populations are at risk. Previous studies show that an oral dose of NS clay was able to reduce AF exposure in a Ghanaian population. In vitro analyses from our laboratory indicated that FB1 (like aflatoxin) could also be sorbed onto the surfaces of NS. Hence, our objectives were to evaluate the efficacy of NS clay to reduce urinary FB1 in a rodent model and then in a human population highly exposed to AF. In the rodent model, male Fisher rats were randomly assigned to either FB1 control, FB1 + 2% NS or absolute control group. FB1 alone or with clay was given as a single dose by gavage. For the human trial, participants received NS (1.5 or 3 g day⁻¹) or placebo (1.5 g day⁻¹) for 3 months. Urines from weeks 8 and 10 were collected from the study participants for analysis. In rats, NS significantly reduced urinary FB1 biomarker by 20% in 24 h and 50% after 48 h compared to controls. In the humans, 56% of the urine samples analysed (n = 186) had detectable levels of FB1. Median urinary FB1 levels were significantly (p < 0.05) decreased by >90% in the high dose NS group (3 g day⁻¹) compared to the placebo. This work indicates that our study participants in Ghana were exposed to FB1 (in addition to AFs) from the diet. Moreover, earlier studies have shown conclusively that NS reduces the bioavailability of AF and the findings from this study suggest that NS clay also reduces the bioavailability FB1. This is important since AF is a proven dietary risk factor for hepatocellular carcinoma (HCC) in humans and FB1 is suspected to be a dietary risk factor for HCC and oesophageal cancer in humans.

Occurrence of fumonisins in Catalonia (Spain) and an exposure assessment of specific population groups.

Fumonisin B1 (FB1) and B2 (FB2) are mycotoxins produced by Fusarium verticillioides and F. proliferatum and common contaminants of cereal crops. The objectives of this study were to (1) study the occurrence of fumonisins in Catalonia (north-eastern region of Spain) and (2) assess the exposure of the Catalonian population to these mycotoxins. Contamination data was provided by a wide survey where 928 individual samples were pooled to analyse 370 composite samples. Fumonisins were extracted and purified using immunoaffinity columns and determined by HPLC with fluorescence detection. The raw consumption data came from a nutritional study specifically designed to assess the dietary intake of the main foodstuffs related to fumonisin contamination for all population age groups. In addition, two specific groups were selected with respect to maize consumption: immigrants and celiac sufferers. Contamination and consumption data were combined by simulation using an essentially parametric-parametric (P-P) method. The P-P method draws sampling values from distribution functions fitted to consumption and contamination datasets. Moreover, to quantify the accuracy and reliability of the statistical estimates, we built related confidence intervals using a Pseudo-Parametric bootstrap method. The results of this study show that fumonisins are commonly found in some commodities on the Catalonian market, such as beer, corn snacks and ethnic foods; however, the values were well below the permitted maximum EU levels. The most exposed group were infants followed by immigrants but, in all cases, they were below the TDI of 2 µg/kg bw/day.

Co-contamination of aflatoxin B1 and fumonisin B1 in food and human dietary exposure in three areas of China.

Aflatoxins and fumonisins are ubiquitous foodborne toxicants and the co-occurrence of these mycotoxins in human foods represents a significant public health concern, which has been strongly associated with human aflatoxicosis, neural tube defects, as well as many types of primary cancers. In this study the co-contamination of aflatoxin B(1) (AFB(1)) and fumonisin B(1) (FB(1)) in food and human dietary exposure was investigated in residents of three different areas of China. A total of 209 food samples were measured for AFB(1) and FB(1). The median AFB(1) levels were 13.5, 2.3 and 1.3 µg kg(-1) and the median FB(1) levels were 2.6, 0.4 and 0.3 mg kg(-1) in corn samples collected from Huaian (a high-risk area for oesophageal cancer), Fusui (a high-risk area for liver cancer) and Huantai (a low-risk area for both oesophageal and liver cancers), respectively. The median level of AFB(1) in plant oil of Fusui was the highest (52.3 µg kg(-1)) among all food samples analysed. Co-contamination of these two mycotoxins was found in corn, rice and wheat flour. Based on measured food consumption data, the averaged daily dietary intake of AFB(1) was 0.397 µg (range = 0.269-1.218 µg) in residents of Huantai, 1.723 µg (0.224-49.772 µg) in Huaian, and 2.685 µg (1.006-14.534 µg) in Fusui. The averaged FB(1) daily dietary intake was 92.4 µg (range = 55.0-362.1 µg) for residents of Huantai, 460.0 µg (83.2-2894.5 µg) in Huaian, and 138.6 µg (30.0-10,541.6 µg) in Fusui. These data suggest that the co-exposure to AFB(1) and FB(1) in residents of rural China may contribute to the aetiology of human chronic diseases in high-risk areas.

Simple intervention method to reduce fumonisin exposure in a subsistence maize-farming community in South Africa.

In the Centane magisterial area of South Africa, high rates of oesophageal cancer have been associated with home-grown maize contaminated with fumonisins. The aim of this study was to implement a simple intervention method to reduce fumonisin exposure in a subsistence-farming community. The hand-sorting and washing procedures, based on traditional maize-based food preparation practices, were previously customised under laboratory-controlled conditions. Home-grown maize and maize-based porridge collected at baseline were analysed for fumonisin B(1), B(2) and B(3). The geometric mean (95% confidence interval) of fumonisin contamination in the home-grown maize at baseline was 1.67 (1.21-2.32) mg kg(-1) and 1.24 (0.75-2.04) mg kg(-1) (dry weight) in the porridge. Fumonisin exposure was based on individual stiff porridge consumption and the specific fumonisin levels in the porridge (dry weight) consumed. Porridge (dry weight) consumption at baseline was 0.34 kg day(-1) and fumonisin exposure was 6.73 (3.90-11.6) µg kg(-1) body weight day(-1). Female participants (n = 22) were trained to recognise and remove visibly infected/damaged kernels and to wash the remaining maize kernels. The discarded kernels represented 3.9% by weight and the fumonisins varied from 17.1 to 76.9 mg kg(-1). The customised hand-sorting and washing procedures reduced fumonisin contamination in the maize and porridge by 84 and 65%, respectively. The intervention reduced fumonisin exposure by 62% to 2.55 (1.94-3.35) µg kg(-1) body weight day(-1). This simple intervention method has the potential to improve food safety and health in subsistence-farming communities consuming fumonisin-contaminated maize as their staple diet.

Evaluation of fumonisin biomarkers in a cross-sectional study with two high-risk populations in China.

Levels of serum and urinary sphinganine (Sa) and sphingosine (So), the Sa/So ratio, and urinary-free fumonisin B(1) (FB(1)) were determined in a cross-sectional study consisting of 43 adults in Huaian and 34 adults in Fusui, China. Home-produced corn had 100% contamination with FB(1). There were 93.0% (40/43) of Huaian subjects and 52.9% (18/34) of Fusui subjects with daily FB(1) intakes greater than 2 microg kg(-1) body weight, which showed a significant difference (p < 0.01). Levels of sphinganine and sphingosine and the Sa/So ratio were not correlated with levels of dietary exposure. The median level of the serum Sa/So ratio in Huaian subjects (0.41, range = 0.14-0.85) was significantly lower than that in Fusui subjects (0.78, range = 0.57-1.08) (p < 0.01). The median level of the urinary Sa/So ratio was also significantly lower in Huaian subjects (0.31, range = 0.08-1.33) than in Fusui subjects (0.57, range = 0.03-2.52) (p < 0.01). Urinary-free FB(1) was detected in 83.7% (36/43) of Huaian samples and in 82.4% (28/34) of Fusui urine samples (p > 0.05). However, the median level of urinary-free FB(1) in Huaian subjects, 3.91 (range = 0.06-253.61) ng mg(-1) creatinine, was significantly higher than 0.39 (range = 0.01-3.72) ng mg(-1) creatinine found in Fusui subjects (p < 0.01). These results suggest that urinary-free FB(1) may be a potential biomarker for human fumonisin exposure, while further validation is needed in human epidemiological and intervention studies.

Toxicokinetics and toxicological effects of single oral dose of fumonisin B1 containing Fusarium verticillioides culture material in weaned piglets.

Toxicokinetics and the toxicological effects of culture material containing fumonisin B(1) (FB(1)) were studied in male weaned piglets by clinical, pathological, biochemical and sphingolipid analyses. The animals received a single oral dose of 5 mg FB(1)/kg of body weight, obtained from Fusarium verticillioides culture material. FB(1) was detected by HPLC in plasma collected at 1-h intervals up to 6h and at 12-h intervals up to 96 h. FB(1) eliminated in feces and urine was quantified over a 96-h period and in liver samples collected 96 h post-intoxication. Blood samples were obtained at the beginning and end of the experiment to determine serum enzyme activity, total bilirubin, cholesterol, sphinganine (Sa), sphingosine (So) and the Sa/So ratio. FB(1) was detected in plasma between 30 min and 36 h after administration. The highest concentration of FB(1) was observed after 2 h, with a mean concentration of 282 microg/ml. Only 0.93% of the total FB(1) was detected in urine between 75 min and 41 h after administration, the highest mean concentration (561 microg/ml) was observed during the interval after 8 at 24 h. Approximately 76.5% of FB(1) was detected in feces eliminated between 8 and 84 h after administration, with the highest levels observed between 8 and 24 h. Considering the biochemical parameters, a significant increase only occurred in cholesterol, alkaline phosphatase and aspartate aminotransferase activities. In plasma and urine, the highest Sa and Sa/So ratios were obtained at 12 and 48 h, respectively.

Cytotoxicity of fumonisin B(1) in spheroid and monolayer cultures of rat hepatocytes.

Fumonisin B(1) (FB(1)), the most prevalent member of toxins produced by several species of Fusarium molds, which occur mainly in maize, causes several fatal hepatopathies and nephropathies of animals. The current study was scrutinized to ascertain different cytotoxic and morphological transformations in rat hepatocytes induced by the treatments of diverse concentrations (300, 500, or 1000 microM) of fumonisin B(1) in vitro, using both monolayer and spheroid cultures. In each hepatocyte culture, the cytotoxicity of FB(1) was augmented in dose- and time-response manners. Morphological transformations among FB(1)-treated groups integrated accumulation of lipid droplets, cytoplasmic vacuolation in hepatocyte monolayers, and bleb formation in the hepatocyte spheroids. Additionally, electron microscopy revealed the loss of microvilli, mitochondrial swelling, and formation of lamellar membranous whorl in the vacuoles and bile canaliculi-like structures. Appearance of electron dense bodies in the monolayers, and loss of cell-to-cell contact in spheroids were depicted in 1000 microM FB(1)-treated hepatocytes. These outcomes insinuate different vital events in explaining morphological transformations in the cell membrane and organelles, induced by fumonisins in rat hepatocytes.

[Etiology of iodinated radiocontrast nephrotoxicity and its attenuation by beraprost].

Radiocontrast nephropathy (RCN) is a major complication after radiographical examination with iodinated contrast media (CM). Although little is known about the mechanism of RCN, a direct toxic action on renal cells and/or decrease in renal blood flow are considered to be implicated in the pathogenesis of the disease/the condition, A large number of vasodilatory agents, including endothelin antagonists, adenosine antagonists, atrial natriuretic peptide, calcium channel blockers, dopamine, dopamine D1 receptor agonist fenoldopam, and prostaglandin E1 have been tried clinically to prevent RCN, however, most of them have failed. Although prophylactic effects of antioxidant N-acetylcysteine have recently been reported by several investigators, only hydration is a universally accepted protocol to prevent it. In our recent in vitro and in vivo study, we have elucidated that CM induced apoptosis of renal tubular cells through the reduction in Bcl-2 expression and the subsequent activation of caspase-9 and caspase-3. Moreover, we found that CM caused an increase in ceramide content in renal tubular cells, which leads to apoptosis by inhibiting the phosphorylation of Akt and cAMP responsive element binding protein (CREB) and the subsequent reduction in Bcl-2 expression. The inhibitor of ceramide synthase, fumonisin B1, reversed both the elevation of ceramide content and renal cell injury induced by CM. On the other hand, a prostacyclin analog beraprost prevented RCN in mice by the increase of endogenous cAMP and subsequent CREB phosphorylation resulted in enhancement of Bcl-2 expression. These findings suggest that ceramide synthesis inhibitor or beraprost is potentially useful for the prophylaxis of RCN.

Early toxic effects of fumonisin B1 in rat liver.

Mycotoxin fumonisin B(1) (FB(1)) is hepatotoxic and carcinogenic in experimental animals. It is known that long-term exposure of experimental animals to FB(1) causes apoptosis and lipid peroxidation. In this study, male adult Wistar rats were treated with single FB(1) doses (5, 50, and 500 microg/kg b.w.) and sacrificed 4, 24, and 48 hours after treatment. Parameters of oxidative stress, histopathological changes, and DNA damage were monitored in the liver of treated and control animals. Parameters of oxidative stress were not affected by such treatment. A significant increase in apoptotic cells appeared in animals when 5 microg/kg b.w. dose was given and sacrificed after 24 hours with further increase at higher doses. In contrast to the number of mitotic figures and karyomegaly seen mostly at lower FB(1) doses, necrosis was the prominent feature at higher doses. Significant increase in liver cells DNA mobility was observed 48 hours following treatment with 50 and 500 microg/kg b.w. as compared to control (tail length 15.2 +/- 0.3, 16.4 +/- 0.5, and 13.5 +/- 0.1 mum, respectively). Tail intensity appeared to be more sensitive parameter for detecting DNA damage even at 5 microg/kg b.w. after 48 hours (1.69 +/- 0.27% DNA; control 0.59 +/- 0.11% DNA). This study proved that FB(1)-induced DNA damage is time- and dose-dependent, and that it could be caused in Wistar rats by a single dose.