Subchronic Feeding Study of the Mycotoxin Fumonisin B1 in B6C3F1 Mice and Fischer 344 Rats

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1 FUNDAMENTAL AND APPLIED TOXICOLOGY 24, 2- (995) Subchronic Feeding Study of the Mycotoxin Fumonisin B in B6CF Mice and Fischer 44 Rats KENNETH A. Voss, WILLIAM J. CHAMBERLAIN, CHARLES W. BACON, RONALD A. HERBERT,* DOUGLAS B. WALTERS,* AND WILLIAM P. NORRED Toxicology and Mycotoxin Research Unit, Agricultural Research Service, USDA, P.O. Box 5677 Athens, Georgia 6; and'national Toxicology Program, NIEHS, P.O. Box 22, Research Triangle Park, North Carolina 2779 Received December 27, 99; accepted June 28, 994 Subchronic Feeding Study of the Mycotoxin Fumonisin Bl in B6CF Mice and Fischer 44 Rats. Voss, K. A., CHAMBER- LAIN, W. J., BACON, C. W., HERBERT, R. A., WALTERS, D. B., AND NORRED, W. P. (995). Fundam. Appl. Toxicol. 24, 2-. Fumonisin Bl (FBI) is a mycotoxin produced by Fusarium moniliforme, a common fungus which occurs naturally on corn, and other Fusarium species. FBI and other fumonisins are now recognized as having potentially important animal and human health implications. However, few toxicologica) data are currently available. Male and female B6CF mice and Fischer 44 rats were fed diets containing,,, 9, 27, or 8 ppm FBI (=98% purity) for weeks. No differences in behavior or appearance, body weight or food consumption between control and FBI-fed groups were found. In mice, hepatopathy and altered serum chemical profiles indicative of hepatotoxicity were found in females fed the 8 ppm diet. No adverse effects were found in female mice fed <27 ppm FBI or in male mice at any dietary level studied. In rats, nephrosis involving the outer medulla was found in males fed >9 ppm and, to a lesser degree, in females fed 8 ppm FBI, while decreased kidney weight was found in both sexes at dietary levels >9 ppm FBI. Although the liver is a target organ of FBI in rats, hepatotoxicity was not found in rats fed diets containing up to 8 ppm FB for 9 days. Thus, FBI was toxic to both species following subchronic oral exposure, although significant interspecies differences in the no observed effect levels and organ-specific responses were found. C 995 Society of Toxicology. Fusarium moniliforme Sheldon, a fungus which commonly grows on corn throughout the world (Marasas et ai, 984b), has long been implicated as an etiological agent of equine leukoencephalomalacia (ELEM) (Wilson and Mar- To whom reprint requests should be addressed at Toxicology and Mycotoxin Research Unit, Richard B. Russell Agricultural Research Center, P.O. Box 5677 Athens, GA 6. onpot, 97; Kellerman et ai, 972) and porcine pulmonary edema (PPE) (Kriek et ai, 98a). F. moniliforme is also associated with human esophageal cancer in areas of southern Africa and China (Marasas et ai, 978, 988a; Yang, 98). Fumonisins were first isolated from F. moniliforme section Liseola by Gelderblom etal\\988) and later from F. proliferatum (Matsushima) Nirenberg, another species of that section (Ross et ai, 99). The fumonisins are also produced by fungi not yet placed within this section including, F. nygamai Burgess & Trimboli, F. dlamini Marasas, Nelson, & Toussoun, and F. napiforme Marasas, Nelson, & Rabie (Marasas et al, 99; Nelson el ai, 99; Thiel et ai, 99), all of which are important because of their association with cereal grains such as corn, millet, and sorghum. Fumonisins occur naturally on corn (Murphy et ai, 99; Sydenham et ai, 99a,b, 99; Voss et ai, 989), animal feeds (Ross et ai, 99a,b; Sydenham et ai, 992), corn-based foods (Pittet et ai, 992; Rheeder et ai, 992; Sydenham et ai, 99; Ueno et ai, 99), and "home grown" corn consumed by humans (Rheeder et ai, 992; Sydenham et ai, 99). Toxicological studies of fumonisins are limited. Early investigations have nonetheless shown that the most commonly occurring isomer, fumonisin Bl (FBI) (Fig. ), causes ELEM (Kellerman et ai, 99; Marasas et ai, 988b), PPE (Harrison et al., 99), and hepatotoxicity in all species examined (Colvin et ai, 99; Gelderblom et ai, 988; Harrison et ai, 99; Marasas et ai, 988b; Voss et al., 99). Gelderblom et al. (99) reported that diets which were marginally deficient in lipotropes, containing 5 ppm FBI, were hepatocarcinogenic to male rats; however, neither the effects of FBI in females nor the effects of lesser dietary concentrations in males were studied. In a preliminary 4-week investigation (Voss et al., 99), the liver and kidney of male and female rats were identified as target organs of FB. The data suggested that the kidney (no observed effect level = NOEL < ppm) was affected at /95 $6. Copyright 995 by the Society of Toxicology. All rights of reproduction in any form reserved. 2 Downloaded from on April 28

2 FUMONISIN Bl TOXICITY IN MICE AND RATS "CH, COOH COCr^CHCHjCOOH I COCHJCHCHJCOOH COOH FIG.. Chemical structure of fumonisin Bl. lower dietary levels than the liver (5 ppm < NOEL < ppm). The effects of fumonisins in mice are unknown although preliminary studies indicate that FBI is probably hepatotoxic to this species as well (Voss et al., 992). Given the importance of the mouse in investigations of xenobiotic toxicity and carcinogenicity, subchronic toxicological data for fumonisins in this species are needed. The present studies were done to compare the subchronic ( week) effects of FB in mice and rats; specifically to identify target organs, to characterize microscopic lesions, and to establish a NOEL for each species. Fumonisin Bl MATERIALS AND METHODS Fumonisin Bl (FBI) was extracted from F. momliforme (strain MRC 826) corn cultures and purified as previously described (Voss el al., 99). Purity (»98%) was assessed by comparison to a fumonisin B standard (R. Vleggaar, Division of Food Science and Technology, Pretoria, Republic of South Africa) using HPLC methods (Voss et al., 99). Diets Diets were prepared fresh weekly and stored frozen. FBI was manually mixed with basal feed (NIH Open Formula 7, certified diet containing <2 ppb aflatoxin and <.5 ppm FB I, Zeigler Brothers, Gardners, PA) to form a premix. The premix was blended into additional basal feed using a Patterson Kelley "V" blender with stirring intensifier bar to produce the 8 ppm diet. The,, 9, and 27 ppm diets were prepared by serial dilution with basal feed. The control group was given basal feed. Diet samples were OH periodically analyzed (n = 7) for FBI concentration using the HPLC method of Ross et al. (99a). Measured FBI concentrations (±SD) of the,,9, 27, and 8 ppm diets averaged.4 ±.5,.2 ±.9, 8.7 ±.64, 26.9 ± 2.7, and 78.4 ± 4.47 ppm, respectively. Animals and Husbandry Male and female B6CF mice and Fischer 44 rats (Taconic Farms, Inc., Germantown, NY), weeks of age, were acclimated for 2 weeks. Animals were individually housed in stainless steel, wire-mesh cages kept by species in environmentally controlled rooms having 2-hr light/dark cycles. Diets and fresh tap water were provided ad libitum. Experimental Design Mice and rats were assigned to six groups of animals/sex by stratified randomization according to body weight. Groups were fed the control or appropriate test diet for weeks. The animals were observed daily. Body weight and food consumption were measured weekly. Weekly FBI consumption (mg/kg BWt) was estimated from body weight, food consumption, and dietary FB concentration data. The animals, with the exception of 5 rats per sex which were randomly selected for 4-week clinical laboratory and pathology evaluations, were killed after weeks. Clinical laboratory studies. Animals were fasted overnight, lightly anesthetized with ether, and bled from the periorbital plexus. Alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (AP), lactate dehydrogenase (LDH), gamma-glutamyltranspeptidase (GGT) and creatine phosphokinase (CPK, rats only) activities, and creatinine, urea nitrogen, glucose, total protein, cholesterol, total bilirubin, triglyceride, and electrolyte (sodium, potassium, calcium, chloride, inorganic phosphorus, and total COJ concentrations were measured after weeks using a Synchron CX5 Clinical System and commercialreagentkits (Beckman Instruments, Brea, CA). In the mouse study, five animals per group were randomly selected for electrolyte measurements, while the remainder were evaluated for serum enzymes and nonelectrolyte constituents. To further investigate the nephrotoxic potential of FBI, BUN and creatinine determinations were also done for those mice selected for electrolyte measurements. For those rats killed after 4 weeks, only ALT, AST, AP, LDH, CPK, GGT, cholesterol, total bilirubin, blood urea nitrogen, and creatinine concentrations were measured..total leukocyte, erythrocyte and platelet counts, hematocrit, hemoglobin concentration, mean corpuscular volume, mean corpuscular hemoglobin, and mean corpuscular hemoglobin concentration were determined in rats killed after weeks using a Model 9 hematology series cell counter (Baker Instruments, Allentown, PA). Differential leukocyte counts were done by visual inspection of Wright-stained blood smears. Pathology. Fasted animals were euthanized (CO 2 gas) and necropsied. The adrenals (rats only), brain, heart, kidneys, liver, lungs, ovaries (rats only), spleen, and testes were weighed and their relative weights (organ to body weight ratios) calculated. The following tissues, orrepresentativepor- TABLE Daily FBI Ingestion (mg/kg BWt) Dietary FBI (ppmf Species Sex Mice Rats Males Females Males Females.* (.25-.8).* (.22^).7* (.7).8' (.8).84* (.68-.) LOC (.85-.9).2* (.2-.22).24' (.2-.25) 2.44* ( ).' (2.8^4.8).62* (.6-.65).7' (.7-.77) 7.8* (6.28-.) 9.7'( ).92* (.8-.99) 2.'( ) 2.*(l8.-.9) 28.9* ( ) 5.66* ( ) 6.5'( ) Note. Values in columns, by species, without shared superscript are significantly different, p <.5. " Values indicate average ipean of weeks. Range of individual mean values are indicated in parentheses; n - for mice, n = 9- for rats. Downloaded from on April 28

3 4 VOSS ET AL. Dietary FBI (ppm) I ; H P ; EZ2, ^2Zk 9: Body Weight, Food Consumption, and FBI Ingestion Mice. Weight gain and food consumption of all groups were similar. Calculated FBI ingestion (mg FBI/kg BWt/ day) of males fed the -8 ppm diets was significantly less (approximately 2%) than that of their respective female groups (Table ). Rats. Weight gain (% initial body weight) of male rats fed 8 ppm FBI was significantly decreased (approximately %) compared to the controls during Week. This decrement did not cause a significant difference in body weight and, after Week, weight gain of all groups was comparable. FBI had no effect upon food consumption. Calculated FBI ingestion of males fed -8 ppm FBI was significantly decreased ( to %) compared to their respective females (Table ). Clinical Laboratory Studies CHOL FIG. 2. Effect offbl on (top) serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), and lactate dehydrogenase (LDH); and (bottom) cholesterol (CHOL), protein (PRTN), and total bilirubin (BLRBN) of female B6CF mice fed FBI for weeks. Values are group means, n = 8 to ; error bars denote SD. Single asterisks identify groups which differ significantly (p <.5) from groups fed lesser FBI concentrations; for CHOL, double asterisk indicates group which differs from groups fed <9 ppm FBI. Mice. Serum cholesterol of males fed,, 27, or 8 ppm FBI was slightly, but significantly, less than control values. ALT, AST, AP, LDH, total protein, and total bilirubin of high-dose females as well as total cholesterol of females fed 27 or 8 ppm FBI were significantly increased (Fig. 2). No other differences were found. Rats. No differences were found for any variable, including serum creatinine, after 4 weeks. After weeks, serum creatinine of males fed 27 ppm FBI was slightly but significantly increased compared to the control group and serum creatinine of high-dose males and females was significantly increased compared to groups fed <27 ppm FBI (Table 2). No other differences between control and FBfed groups were found for either sex after weeks. Organ Weights tions thereof, and all gross lesions werefixedin Carson's buffered formalin, stained with hematoxylin and eosin, and examined (without knowledge of treatment) by light microscopy: adrenals, aorta, brain (mice only), epididymis, esophagus, eye/periorbital gland, gall bladder (mice only), heart, large intestine, small intestine, kidney, liver, lungs, mammary gland, mesenteric lymph node, pancreas, ovaries, prostate, salivary glands, sciatic nerve, seminal vesicles, skeletal (thigh) muscle, skin, spleen, sternum with marrow, stomach, testes, thymus, thyroid with parathyroids, trachea, urinary bladder, and uterus. Lesion severity was subjectively scored as minimal, mild, moderate, or severe. Histopathologjcal findings in target organs, including lesion severity, were independently reviewed and confirmed. The brains from all rats were stored frozen for ongoing neurochemical studies. Statistics. Data were analyzed by parametric and nonparametric methods using the scheme of Gad and Weil (982). Significance was judged atp <.5. RESULTS Clinical Observations FBI had no effect upon survival, appearance, or behavior of either species. Downloaded from on April 28 Mice. No organ weight effects were found. Rats. Absolute (g) and relative (% BWt) kidney weights of males fed 27 or 8 ppm FBI were significantly decreased after both 4 and weeks (Table 2). Kidney weight of males fed 9 ppm FB did not differ from those of the control group after 4 weeks. However, absolute kidney weight of this group was significantly decreased after weeks. No differences in kidney weight were found for females after 4 weeks. After weeks, relative kidney weight of females fed >9 ppm, as well as absolute and relative kidney weights of females fed =27 ppm FB, was significantly decreased. No other organ weight effects were found. Pathology Necropsy findings in both species were infrequent and fortuitously distributed, and considered incidental. Microscopic lesions related to FB were found in the liver and adrenals of female mice and the kidneys of rats.

4 FUMONISIN Bl TOXICITY IN MICE AND RATS TABLE 2 Final Body Weights (BWt), Absolute (g) and Relative (% BWt) Kidney Weights, and Serum Creatinine (Creat.) Concentrations of Male and Female Fischer 44 Rats Fed FBI for 4 or Weeks 4 weeks (n = 5) weeks (n = ) Diet (ppm) BWt(g) Kidney weight (% BWt) Creat. (mg/dl) BWt(g) Kidney weight (g) (% BWt) Creat. (mg/dl) Males (2.) 25(4.) 28(2.2) 27 (22.) 25 (24.) 24 (24.7) 2. (.22) 2.6 (.2) 2.6" (.) 2.^(.).84".75' (.22) (.9).88* (.).86 (.5).87 (.).85 (.).78* (.5).75* (.).49 (.7).44 (.2).45 (.4).46 (.4).48 (.4).47 (.7) (8.2) ;..52 (.4) (25.4) ;..64 (.2) 5(.4) :!.58' (.8) 24(2.4) :!.8* (.7) 28 (27.) ; >.7' (.2) (9.4) ; 2.5' (.).77** (.5).79 (.4).77 * (.4).7* (.5).67' (.7).6 l rf (.).45' (.5).49 * (.6).48** (.4).49 * (.7).5* (.).58' (.6) Females (.5) 42 (5.56) 45(7.98) 9(8.2) 46(.9) 4(7.) (.4) (.) (.8) (.5) (.7) (.7).88 (.).89 (.5).87 (.4).9 (.).86 (.4).85 (.4).5(.8).5 (.9).54(.).5(.).46 (.5).49 (.4) 8 (7.9) 79(4.4) 82(2.) 82(6.7) 7(2.) 76(4.).48 (.6).42 (.4).45* (.).4** (.2).* (.8).28' (.7).82 (.4).79* 4 (.4).8** (.).77* (.7).76" (.7).7' (.).49* (.6).5 (.).49* (.6).52* (.4).5* (.5).62* (.6) Note. Values in columns without shared superscript are significantly different, p <.5. Mice. Liver lesions, designated hepatopathy, were mild and limited to (all) high-dose females. The lesions were primarily centrilobular, although some midzonal involvement and bridging between central areas was seen (Fig. ). The principal features included individual hepatocyte necrosis and cytomegaly, increased numbers of mitotic figures, mixed neutrophil and macrophage infiltrates, and macrophage pigmentation. In some areas, there was an apparent loss of hepatocytes with collapse of the centrilobular zone. Macrophages within the adrenal cortex (x zone) of all females fed 8 ppm FB and two females fed 27 ppm FB contained minimal to mild amounts of a cytoplasmic pigment which was morphologically consistent with ceroid. Rats. Nephrosis was found in males fed 9, 27, or 8 ppm FBI and in females fed 8 ppm FBI (Table ). Within groups, there was no obvious difference in lesion severity or qualitative appearance of the kidneys from rats killed after 4 or weeks. Lesions found in males fed 8 ppm were generally mild but more obvious than those found at 27 ppm FBI, while lesions found in the latter group were more severe than the minimal histological changes seen in males fed 9 ppm or females fed 8 ppm FBI. The lesions were predominantly located in the outer stripe of the medulla with the more obvious lesions extending into the medullary rays. Typically, individual tubular cells were degenerate or necrotic. Pyknotic nuclei were scattered throughout the affected portion of the tubules and some necrotic cells with pyknotic nuclei and eosinophilic cytoplasm were sloughed into the tubular lumina. Other features were generalized cytoplasmic basophilia, slightly decreased cell size, and increased luminal diameter (Fig. 4). Mitoticfigureswere sporadically present and light chronic inflammatory infiltrates were occasionally found in the affected areas. No glomerular and vascular lesions were found. No Observed Effect Levels Based on the findings of this study, the NOEL for FBI was higher in mice than in rats. NOELs for the respective species were 27 and ppm. DISCUSSION The effects of purified FB in the mouse have not previously been reported, although fumonisin-containing diets formulated with crude F. moniliforme culture material were hepatotoxic to both male (Voss et ai, 992) and female mice (Voss et at., unpublished observations). Serum chemical profiles and microscopic liver lesions caused by culture material and by FB in this investigation were qualitatively similar. Thus, as with rats (Gelderblom et at., 988; Voss et ai, 99), the liver is a target organ of F. moniliforme in mice and hepatotoxicity is caused, at least in part, by FBI. Hepatic injury in this study was mild and limited to Downloaded from on April 28

5 6 VOSS ET AL. FIG.. Photomicrograph ofliver from female B6CF mouse fed8 ppmfbl for weeks. Note loss of cells from centrilobular areas (open arrow), single cell necrosis (solid arrows), hepatocellular cytomegaly and mitotic figure (curved arrow) (hematoxylin and eosin, X45). high-dose females. Although a sex-related difference in response cannot be dismissed, the absence of lesions in males may have simply reflected the persistently lower amount of FBI (mg/kg BWt) ingested by the latter. In female mice, the x zone of the adrenal is transient and normally disappears with the first pregnancy, but is retained for longer periods in nonparous females. The relationship between increased pigment deposition in the x zone of female mice and FBI ingestion is not known; however, this change may represent an early onset of degeneration and atrophy. X zone degeneration and atrophy has been reported to occur more rapidly in mice following the administration of some chemicals and corticosteroids (Dunn, 97; Ribelin, 984). An association between the hepatic lesions and the changes in the adrenal gland may be also be possible, while others have related the presence of ceroid in the adrenal gland to altered fat metabolism (Schardein et al., 967). Toxicological findings in rats were limited to the kidneys. Minimal to mild nephrosis was qualitatively similar to that found in earlier studies of/7, moniliforme (Voss et al., 989, 992) and FBI (Voss et al., 99) and, as reported previously, lesions were more extensive and occurred at lower dietary FBI concentrations in males than in females. However, decreased kidney weight, a consistent finding in rats Downloaded from on April 28 exposed to F. moniliforme or FBI (Voss et al., 989, 992, 99, unpublished observations), was found after weeks in both males and females fed >9 ppm FBI. This suggests that nephrosis may also have eventually developed in females following prolonged (> weeks) ingestion of the 9 or 27 ppm diets. Because estimated FBI ingestion (mg/kg BWt) in each group was significantly higher in females than in males, it can be inferred that there was a sex-related difference in the nephrotoxic response of rats to FB. This may have resulted from differences in proximal tubular function between male and female Fischer 44 rats or enhancement of toxicity by testosterone (Montgomery and Seely, 99). Alternatively, it has been suggested (Riley et al., 99b) that FBI induces nephropathy in rats by inhibiting renal sphingolipid metabolism and that males appeared to be more sensitive to this effect than females. If so, differences in renal response of male and female rats to FBI may have been a function of sex-related differences in kidney sphingolipid metabolism. Interestingly, induction of acute proximal tubular necrosis, increased serum creatinine concentrations, and altered renal sphingolipid profiles by intravenous injection of FBI to rabbits have also been reported recently (Gumprecht et al., 994). Kriek et al., (986) reported that rats fed F. moniliforme apparently adapt, insofar as the kidney is concerned, to

6 TABLE Incidence and Severity of Renal Lesions (Nephrosis) Found in Male and Female Fischer 44 Rats Fed FBI for 4 (n = 5) or (n = ) Weeks Finding Incidence (total animals) Normal Nephrosis Severity (number of lesions classified as) Minimal 4 weeks weeks Mild 4 weeks weeks Incidence (total animals) Normal Nephrosis Severity (number of lesions classified as) Minimal 4 weeks weeks Males Females FUMONISIN Bl TOXICITY IN MICE AND RATS 7 Dietary FBI (ppm) 9 ' 4" " " " " Note. Incidences designated by superscript differ significantly (p <.5) from controls T 8" 5 continued exposure and that renal lesions disappear within 4 to 6 weeks following their onset. Our results do not support this finding as lesions found after 4 and weeks were morphologically indistinguishable. Furthermore, decreased kidney weights in males fed 9 ppm FBI, decreased kidney weights in females fed >9 ppm FBI, and increased serum creatinine concentrations in males fed >2 ppm and females fed 8 ppm FBI were found after, but not 4, weeks. This suggests that tubular injury, albeit slight, persisted or was slightly exacerbated as FBI exposure continued. In earlier studies, diets containing 5 ppm FB were hepatotoxic to male BD IX rats after 26 weeks (Gelderblom et al, 99) while diets with ppm FBI were hepatotoxic to male and female Sprague-Dawley rats after 2 to 4 weeks (Voss et al, 99). The FB concentration of our high-dose diet, 8 ppm, did not cause liver injury. The extent to which differences inherent in the various rat strains and basal diets used, especially the (marginally) lipotrope-deficient diet used by Gelderblom et al. (99), influenced hepatotoxic response is unknown. Additional studies are needed to define the dose-response and NOEL for hepatotoxicity following subchronic and chronic FBI ingestion. Results of this study nonetheless confirm and extend our previous findings that FB is nephrotoxic at dosages which are not hepatotoxic. As in the studies of Gelderblom et al. (99) and Voss et al. (99), no evidence of testicular, esophageal, cardiovascular, or other findings attributed to F. moniliforme(kiieketal, 98b;Marasas^a/., 984a) was found and the fungal metabolites putatively responsible for these effects remain unidentified. FBI specifically inhibits the enzyme sphinganine (sphingosine) N-acyltransferase and consequently prevents the de novo biosynthesis of ceramide (Wang et al, 99). Wang et al. (99) hypothesized that disruption of sphingolipid metabolism leading to an increased cellular sphinganine/ sphingosine ratio (Sa/So) is a likely mechanism of fumonisin toxicity. Both FB and F. moniliforme increase Sa/So in in vitro systems (Riley et al., 992; Yoo et al, 992) and in tissues from various species in vivo (Riley et al, 99a; Wang et al, 992). In rats, Sa/So of liver and kidneys was increased by FBI (Riley et al., 99b), the increases appeared dose-related, and elevated Sa/So occurred prior to the onset of renal or hepatic injury as demonstrated by conventional serum chemical and histopathological methods. On the contrary, Haschek et al. (99) reported that fumonisin-induced sphingolipid alterations in swine did not correlate well with target organ pathology. Sphingolipid measurements were not undertaken in this study and, therefore, the effect of continuous FB ingestion on sphingolipids of mice and rats remains unknown. Our findings do suggest, however, that comparative investigations of FB exposure on liver and kidney sphingolipid homeostasis in these and other species may be useful for determining the mechanicam of fumonisin toxicity and for further defining the physiological functions of sphingolipids. Fumonisins have been found in corn-based food products from around the world (Pittet et al, 992; Rheeder et al., 992; Sydenham et al, 99; Ueno et al., 99). Relatively high levels of FBI, up to 2.8 ppm, were found in commercially purchased food from the United States (Sydenham et al, 99). In southern Africa, ppm FBI were found in "clean" samples of home-grown corn intended for human consumption while higher levels, up to 7 ppm FB, were found in moldy corn samples from a nearby region having a high human esophageal cancer rate (Rheeder et al, 992; Sydenham et al, 99). Interestingly, dietary NOELs for FBI obtained in this 9-day study, ppm in rats and 27 ppm in mice, were within the aforementioned ranges. Given these NOELs, the occurrence of fumonisins in feeds and foods, and indications that other fumonisins, particularly fumonisin B2, may exert similar biological effects (Gelderblom et al, 99), additional investigations to determine the chronic effects of these compounds are warranted. Downloaded from on April 28

7 8 VOSS ET AL. FIG. 4. Photomicrograph of kidney (outer medulla) of male Fischer 44 rat fed 8 ppm FBI for weeks. Note decreased epithelial cell size and increased luminal diameter (open arrows) and degenerate and necrotic epithelial cells (long arrow), some of which have pyknotic nuclei and are sloughed into the tubular lumina (short arrow) (hematoxylin and eosin, X45). Gelderblom, W. C. A., Cawood, M. E., Snyman, S. D., Vleggaar, R., and Marasas, W. F. O. (99). Structure-activityrelationshipsof fumonisins in short-term carcinogenesis and cytotoxicity assays. Food Chem. ToxiThe authors thank R. Bennett, N. Brice, P. Hayes, M. Nelms, P. Stancel, cot., K_ Tate, and E. Wray for their technical expertise. We also thank Dr. W. F. O. Marasas for generously supplying M RC 826, Dr. P. K. Hildebrant Gumprecht, L. A., Marcucci, A., Vesonder, R. F., Peterson, R. E., Scott, for pathology consultation, and Dr. G. A. Boorman for his consultations. J. R., Riley, R. T., Showker, J. L., Beasley, V. R., and Haschek, W. M. This work was jointly sponsored by the Agricultural Research Service, (994). Nephrotoxicity in rabbits induced by iv fumonisin B. ToxicoloUSDA and the National Toxicology Program, NIEHS under Interagency gist 4, 28. Research Agreement M-6. Harrison, L. R., Colvin, B. M., Greene, J. T., Newman, L. E., and Cole, J. R., Jr. (99). Pulmonary edema and hydrothorax in swine produced by fumonisin Bl, a toxic metabolite of Fusarium moniliforme. J. Vet. REFERENCES Diagn. Invest. 2, Colvin, B. M., Cooley, A. J., and Beaver, R. W. (99). Fumonisin toxico- Haschek, W. M., Kim, H-Y., Motelin, G. K., Stair, E. L., Beasley, V. R., sis in swine: Clinical and pathologic findings. J. Vet. Diagn. Invest. 5, Chamberlain, W. J., and Riley, R. T. (99). Pure fumonisin BI, as well as fumonisin-contaminated feed, alters swine serum and tissue sphin ganine and sphingosine levels, biomarlcers of exposure. Toxicologist, Dunn, T. B. (97). Normal and pathologic anatomy of the adrenal gland 22. of the mouse including neoplasms. J. Nail. Cancer Insl 44, Gad, S. C, and Weil, C. S. (982). Statistics for toxicologists. In Principles Kellerman, T. S., Marasas, W. F. O., Pienaar, J. G., and Naude, T. W. (972). A mycotoxicosis of equidae caused by Fusarium moniliforme and Methods of Toxicology (A. W. Hayes, Ed.), pp Raven Sheldon. A preliminary communication. Onderstepoort J. Vet. Res. 9, Press, New York Gelderblom, W. C. A., Jaskiewicz, K., Marasas, W. F. O., Thiel, P. G., Horak, R. M., Vleggaar, R., and Kriek, N. P. J. (988). Fumonisins Kellerman, T. S., Marasas, W. F. O., Thiel, P. G., Gelderblom, W. C. A., Cawood, M., and Coetzer, J. A. W. (99). Leukoencephalomalacia in Novel mycotoxins with cancer promoting activity produced by Fusartwo horses induced by oral dosing of fumonisin Bl. Onderstepoort J. ium moniliforme. Appl. Environ. Microbiol. 54, Vet. Res. 57, Gelderblom, W. C. A., Kriek, N. P. J., Marasas, W. F. O., and Thiel, P. G. (99). Toxicity and carcinogenicity of the Fusarium moniliforme me- Kriek, N. P. J., Kellerman, T. S., and Marasas, W. F. O. (98 a). Comparative study of the toxicity of Fusarium \enicillioides(=f. moniliforme) to tabolite, fumonisin Bl in rats. Carcinogenesis 2, ACKNOWLEDGMENTS Downloaded from on April 28

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