1 4819 114 OCCURRENCE OF TOXICITY AND CELL PROLIFERATION AFTER A SINGLE GAVAGE ADMINISTRATION OF CHLOROFORM TO MALE F344 RATS. CHLOROFORM, AN INDUSTRIAL SOLVENT AND ONE OF THE MOST COMMON ENVIRONMENTAL CONTAMINANTS WHICH PRODUCES CARCINOGENIC EFFECTS IN THE LIVER AND KIDNEY OF RODENTS, IS NOT GENOTOXIC IN MOST TRADITIONAL BACTERIAL AND MAMMALIAN TEST SYSTEMS. ITS CARCINOGENIC POTENTIAL APPEARS ATTRIBUTABLE TO THE SUSTAINED CELL TURNOVER (REGENERATIVE HYPERPLASIA) WHICH RESULTS FROM CHRONIC CHLOROFORM TOXICITY. IN THIS PRESENT STUDY, CELL PROLIFERATION (REPLICATIVE DNA SYNTHESIS, RDS) AND HISTOPATHOLOGICAL CHANGES IN HEPATOCYTES AND RENAL TUBULAR EPITHELIAL CELLS WERE ASSESSED IN MALE F344 RATS FOLLOWING A SINGLE GAVAGE CHLOROFORM EXPOSURE (50, 150 OR 500 MG/KG). IN ADDITION, BIOCHEMICAL PARAMETERS (BUN, GOT, LDH AND NAG) WERE EXAMINED USING PLASMA AND URINE SAMPLES. CELL PROLIFERATION AND HISTOPATHOLOGICAL CHANGES (E.G. HYPERTROPHY, NECROSIS, VACUOLATION) WERE ONLY SEEN AT THE DOSE OF 500 MG/KG IN THE LIVER AND KIDNEY. AT THE SAME DOSE, ALL BIOCHEMICAL MARKERS WERE INCREASED AT THE 24 TO 48 HR TIME POINTS. THESE RESULTS OBTAINED ARE THUS IN LINE WITH EARLIER FINDINGS POINTING TO EPIGENETIC CARCINOGENICITY. 1998 2 4121 35 MECHANISMS OF CHEMICALLY INDUCED RENAL CARCINOGENESIS IN THE LABORATORY RODENT. LABORATORY STUDIES WITH CLASSICAL RENAL CARCINOGENS IN THE RAT AND MOUSE, AS WELL AS RESEARCH INVESTIGATION WITH SOME OF THE CHEMICALS PROVING POSITIVE FOR THE KIDNEY IN NATIONAL TOXICOLOGY PROGRAM CARCINOGENICITY BIOASSAYS, HAVE DEMONSTRATED THE EXISTENCE OF A RANGE OF DIVERSE MECHANISMS UNDERLYING RODENT KIDNEY CARCINOGENESIS. THE CLASSICAL CARCINOGENS USED AS EXPERIMENTAL MODELS FOR STUDYING RENAL TUMOR PATHOGENESIS, SUCH AS THE NITROSAMINES, ARE GENOTOXIC AND INTERACT DIRECTLY WITH DNA, FORMING DNA ADDUCTS WITH MUTAGENIC POTENTIAL. IN CONTRAST, POTASSIUM BROMATE AND FERRIC NITRILOTRIACETATE (FE-NTA), ALSO EFFECTIVE RENAL CARCINOGENS, APPEAR TO CAUSE INDIRECT DAMAGE TO DNA MEDIATED BY OXIDATIVE STRESS. A NUMBER OF NONGENOTOXIC CHEMICALS ARE ASSOCIATED WITH EPIGENETIC RENAL TUMOR INDUCTION IN RODENTS, AND THE ACTIVITY OF THESE TENDS TO INVOLVE PROLONGED STIMULATION OF CELL PROLIFERATION THROUGHOUT THE DURATION OF EXPOSURE. THIS MODE OF ACTION REFLECTS A SUSTAINED REGENERATIVE RESPONSE, EITHER DUE TO DIRECT CHEMICAL TOXICITY TO THE TUBULE CELLS, AS WITH CHLOROFORM, OR TO INDIRECT CYTOTOXICITY ASSOCIATED WITH LYSOSOMAL OVERLOAD, AS IN ALPHA2U-GLOBULIN ACCUMULATION IN MALE RATS RESULTING FROM THE ADMINISTRATION OF SUCH CHEMICALS AS D-LIMONENE AND TETRACHLOROETHYLENE. THE HISTOPATHOLOGIC NATURE OF HYDROQUINONE RENAL CARCINOGENESIS SUGGESTS THAT AN ADDITIONAL EPIGENETIC PATHWAY TO RENAL TUBULE TUMOR FORMATION IN RATS MAY BE THROUGH CHEMICAL-MEDIATED EXACERBATION OF, AND INTERACTION WITH, THE AGE-RELATED SPONTANEOUS RENAL DISEASE, CHRONIC PROGRESSIVE NEPHROPATHY. THESE VARIOUS MECHANISTIC PATHWAYS HAVE IMPLICATIONS FOR THE NATURE OF THE INDUCED CANCER PROCESS WITH RESPECT TO TUMOR INCIDENCE, LATENCY, MALIGNANCY, AND SEX PREDISPOSITION. 1998 3 1295 25 DECREASED GLOBAL DNA METHYLATION IN THE WHITE BLOOD CELLS OF HIGH FAT DIET FED VERVET MONKEYS (CHLOROCEBUS AETHIOPS). EPIGENETIC MECHANISMS ARE ASSOCIATED WITH THE DEVELOPMENT OF MANY CHRONIC DISEASES AND DUE TO THEIR REVERSIBLE NATURE OFFER A UNIQUE WINDOW OF OPPORTUNITY TO REVERSE THE DISEASE PHENOTYPE. THIS STUDY INVESTIGATED WHETHER GLOBAL DNA METHYLATION CORRELATES WITH DYSGLYCEMIA IN THE VERVET MONKEY (CHLOROCEBUS AETHIOPS). DIET-INDUCED CHANGES IN DNA METHYLATION WERE OBSERVED WHERE GLOBAL DNA METHYLATION WAS TWOFOLD LOWER IN MONKEYS FED A HIGH FAT DIET (N = 10) COMPARED TO MONKEYS FED A STANDARD DIET (N = 15). AN INVERSE CORRELATION WAS OBSERVED BETWEEN DNA METHYLATION, BLOOD GLUCOSE CONCENTRATIONS, BODYWEIGHT, AND AGE, ALTHOUGH THE ASSOCIATION WAS NOT STATISTICALLY SIGNIFICANT. CONSUMPTION OF A HIGH FAT DIET IS ASSOCIATED WITH THE DEVELOPMENT OF METABOLIC DISEASE; THUS, THESE RESULTS SUGGEST THE USE OF GLOBAL DNA METHYLATION AS A BIOMARKER TO ASSESS THE RISK FOR METABOLIC DISEASE. MOREOVER, THIS STUDY PROVIDES FURTHER SUPPORT FOR THE USE OF THE VERVET MONKEY AS A MODEL SYSTEM TO STUDY METABOLIC DISEASES SUCH AS TYPE 2 DIABETES. INTEGRATION OF ALTERED DNA METHYLATION PROFILES INTO PREDICTIVE MODELS COULD FACILITATE RISK STRATIFICATION AND ENABLE INTERVENTION STRATEGIES TO INHIBIT DISEASE PROGRESSION. SUCH INTERVENTIONS COULD INCLUDE LIFESTYLE MODIFICATIONS, FOR EXAMPLE, THE INCREASED CONSUMPTION OF FUNCTIONAL FOODS WITH THE CAPACITY TO MODULATE DNA METHYLATION, THUS POTENTIALLY REVERSING THE DISEASE PHENOTYPE AND PREVENTING DISEASE. 2014 4 1819 28 EFFECTS OF CHRONIC OCHRATOXIN A EXPOSURE ON P53 HETEROZYGOUS AND P53 HOMOZYGOUS MICE. EXPOSURE TO THE MYCOTOXIN OCHRATOXIN A (OTA) CAUSES NEPHROPATHY IN DOMESTIC ANIMALS AND RODENTS AND RENAL TUMORS IN RODENTS AND POULTRY. HUMANS ARE EXPOSED TO OTA BY CONSUMING FOODS MADE WITH CONTAMINATED CEREAL GRAINS AND OTHER COMMODITIES. MANAGEMENT OF HUMAN HEALTH RISKS DUE TO OTA EXPOSURE DEPENDS, IN PART, ON ESTABLISHING A MODE OF ACTION (MOA) FOR OTA CARCINOGENESIS. TO FURTHER INVESTIGATE OTA'S MOA, P53 HETEROZYGOUS (P53+/-) AND P53 HOMOZYGOUS (P53+/+) MICE WERE EXPOSED TO OTA IN DIET FOR 26 WEEKS. THE FORMER ARE SUSCEPTIBLE TO TUMORIGENESIS UPON CHRONIC EXPOSURE TO GENOTOXIC CARCINOGENS. OTA-INDUCED RENAL DAMAGE BUT NO TUMORS WERE OBSERVED IN EITHER STRAIN, INDICATING THAT P53 HETEROZYGOSITY CONFERRED LITTLE ADDITIONAL SENSITIVITY TO OTA. RENAL CHANGES INCLUDED DOSE-DEPENDENT INCREASES IN CELLULAR PROLIFERATION, APOPTOSIS, KARYOMEGALY, AND TUBULAR DEGENERATION IN PROXIMAL TUBULES, WHICH WERE CONSISTENT WITH OCHRATOXICOSIS. THE LOWEST OBSERVED EFFECT LEVEL FOR RENAL CHANGES IN P53+/- AND P53+/+ MICE WAS 200 MUG OTA/KG BW/DAY. BASED ON THE LACK OF TUMORS AND THE SEVERITY OF RENAL AND BODY WEIGHT CHANGES AT A MAXIMUM TOLERATED DOSE, THE RESULTS WERE INTERPRETED AS SUGGESTIVE OF A PRIMARILY NONGENOTOXIC (EPIGENETIC) MOA FOR OTA CARCINOGENESIS IN THIS MOUSE MODEL. 2015 5 4821 39 OCHRATOXIN A: 13-WEEK ORAL TOXICITY AND CELL PROLIFERATION IN MALE F344/N RATS. OCHRATOXIN A (OTA) IS NEPHROTOXIC AND A POTENT RENAL CARCINOGEN. MALE RATS ARE MOST SUSCEPTIBLE TO OTA TOXICITY, AND CHRONIC ADMINISTRATION OF OTA (70 AND 210 MICROG/KG BW) FOR 2 YEARS HAS BEEN SHOWN TO INDUCE HIGH INCIDENCES OF ADENOMAS AND CARCINOMAS ARISING FROM THE STRAIGHT SEGMENT OF THE PROXIMAL TUBULE EPITHELIUM. IN CONTRAST, TREATMENT WITH A LOWER DOSE OF 21 MICROG/KG BW DID NOT RESULT IN INCREASED TUMOR RATES, SUGGESTING A NONLINEAR DOSE RESPONSE FOR RENAL TUMOR FORMATION BY OTA. SINCE THE MECHANISM OF OTA CARCINOGENICITY IS STILL LARGELY UNKNOWN, THIS STUDY WAS CONDUCTED TO INVESTIGATE EARLY FUNCTIONAL AND PATHOLOGICAL EFFECTS OF OTA AND TO DETERMINE IF SUSTAINED STIMULATION OF RENAL CELL PROLIFERATION PLAYS A ROLE. MALE F344/N RATS WERE TREATED WITH OTA FOR UP TO 13 WEEKS UNDER CONDITIONS OF THE NATIONAL TOXICOLOGY PROGRAM (NTP) BIOASSAY. CELL PROLIFERATION IN THE RENAL CORTEX AND OUTER STRIPE OF THE OUTER MEDULLA (OSOM) WAS DETERMINED USING BROMODEOXYURIDINE INCORPORATION AND IMMUNOHISTOCHEMISTRY. HISTOPATHOLOGICAL EXAMINATION SHOWED RENAL ALTERATIONS IN MID- AND HIGH-DOSE-TREATED ANIMALS INVOLVING SINGLE-CELL DEATH AND PROMINENT NUCLEAR ENLARGEMENT WITHIN THE STRAIGHT PROXIMAL TUBULES. TREATMENT WITH OTA AT DOSES OF 70 AND 210 MICROG/KG BW LED TO A MARKED DOSE- AND TIME-DEPENDENT INCREASE IN RENAL CELL PROLIFERATION, EXTENDING FROM THE MEDULLARY RAYS INTO THE OSOM. NO EFFECTS WERE EVIDENT IN KIDNEYS OF LOW-DOSE-TREATED ANIMALS OR IN THE LIVER, WHICH IS NOT A TARGET FOR OTA CARCINOGENICITY. A NO OBSERVED EFFECT LEVEL IN THIS STUDY WAS ESTABLISHED AT 21 MICROG/KG BW, CORRELATING WITH THE DOSE IN THE NTP 2-YEAR BIOASSAY THAT DID NOT PRODUCE RENAL TUMORS. THE APPARENT CORRELATION BETWEEN ENHANCED CELL TURNOVER AND TUMOR FORMATION INDUCED BY OTA INDICATES THAT STIMULATION OF CELL PROLIFERATION MAY PLAY AN IMPORTANT ROLE IN OTA CARCINOGENICITY AND PROVIDES FURTHER EVIDENCE FOR AN EPIGENETIC, THRESHOLDED MECHANISM. 2007 6 5843 31 STUDIES ON THE CARCINOGENICITY OF POTASSIUM IODIDE IN F344 RATS. A CHRONIC TOXICITY AND CARCINOGENICITY STUDY, IN WHICH MALE AND FEMALE F344/DUCRJ RATS WERE GIVEN POTASSIUM IODIDE (KI) IN THE DRINKING WATER AT CONCENTRATIONS OF 0, 10, 100 OR 1000 PPM FOR 104 WEEKS, AND A TWO-STAGE CARCINOGENICITY STUDY OF APPLICATION AT 0 OR 1000 PPM FOR 83 WEEKS FOLLOWING A SINGLE INJECTION OF N-BIS(2-HYDROXYPROPYL)NITROSAMINE (DHPN), WERE CONDUCTED. IN THE FORMER, SQUAMOUS CELL CARCINOMAS WERE INDUCED IN THE SALIVARY GLANDS OF THE 1000 PPM GROUP, BUT NO TUMORS WERE OBSERVED IN THE THYROID. IN THE TWO-STAGE CARCINOGENICITY STUDY, THYROIDAL WEIGHTS AND THE INCIDENCE OF THYROID TUMORS DERIVED FROM THE FOLLICULAR EPITHELIUM WERE SIGNIFICANTLY INCREASED IN THE DHPN+KI AS COMPARED WITH THE DHPN ALONE GROUP. THE RESULTS OF OUR STUDIES SUGGEST THAT EXCESS KI HAS A THYROID TUMOR-PROMOTING EFFECT, BUT KI PER SE DOES NOT INDUCE THYROID TUMORS IN RATS. IN THE SALIVARY GLAND, KI WAS SUGGESTED TO HAVE CARCINOGENIC POTENTIAL VIA AN EPIGENETIC MECHANISM, ONLY ACTIVE AT A HIGH DOSE. 2000 7 3623 39 IN VIVO COMET ASSAY ON ISOLATED KIDNEY CELLS TO DISTINGUISH GENOTOXIC CARCINOGENS FROM EPIGENETIC CARCINOGENS OR CYTOTOXIC COMPOUNDS. THE OBJECTIVE OF THIS STUDY WAS TO DETERMINE THE ABILITY OF THE ALKALINE IN VIVO COMET ASSAY (PH>13) TO DISTINGUISH GENOTOXIC CARCINOGENS FROM EPIGENETIC CARCINOGENS WHEN PERFORMED ON FRESHLY ISOLATED KIDNEY CELLS AND TO DETERMINE THE POSSIBLE INTERFERENCE OF CYTOTOXICITY BY ASSESSING DNA DAMAGE INDUCED BY RENAL GENOTOXIC, EPIGENETIC OR TOXIC COMPOUNDS AFTER ENZYMATIC ISOLATION OF KIDNEY CELLS FROM OFA SPRAGUE-DAWLEY MALE RATS. THE ABILITY OF THE COMET ASSAY TO DISTINGUISH (1) GENOTOXICITY VERSUS CYTOTOXICITY AND (2) GENOTOXIC VERSUS NON-GENOTOXIC (EPIGENETIC) CARCINOGENS, WAS THUS INVESTIGATED BY STUDYING FIVE KNOWN GENOTOXIC RENAL CARCINOGENS ACTING THROUGH DIVERSE MECHANISMS OF ACTION, I.E. STREPTOZOTOCIN, ARISTOLOCHIC ACIDS, 2-NITROANISOLE, POTASSIUM BROMATE AND CISPLATIN, TWO RODENT RENAL EPIGENETIC CARCINOGENS: D-LIMONENE AND CICLOSPORINE AND TWO NEPHROTOXIC COMPOUNDS: STREPTOMYCIN AND INDOMETHACIN. ANIMALS WERE TREATED ONCE WITH THE TEST COMPOUND BY THE APPROPRIATE ROUTE OF ADMINISTRATION AND GENOTOXIC EFFECTS WERE MEASURED AT THE TWO SAMPLING TIMES OF 3-6 AND 22-26H AFTER TREATMENT. REGARDING THE TISSUE PROCESSING, THE LIMITED BACKGROUND LEVEL OF DNA MIGRATION OBSERVED IN THE NEGATIVE CONTROL GROUPS THROUGHOUT ALL EXPERIMENTS DEMONSTRATED THAT THE ENZYMATIC ISOLATION METHOD IMPLEMENTED IN THE CURRENT STUDY IS APPROPRIATE. ON THE OTHER HAND, STREPTOZOTOCIN, 20MG/KG, USED AS POSITIVE REFERENCE CONTROL CONCURRENTLY TO EACH ASSAY, CAUSED A CLEAR INCREASE IN THE MEAN OLIVE TAIL MOMENT MEDIAN VALUE, WHICH ALLOWS VALIDATING THE CURRENT METHODOLOGY. UNDER THESE EXPERIMENTAL CONDITIONS, THE IN VIVO RODENT COMET ASSAY DEMONSTRATED GOOD SENSITIVITY AND GOOD SPECIFICITY: ALL THE FIVE RENAL GENOTOXIC CARCINOGENS WERE CLEARLY DETECTED IN AT LEAST ONE EXPRESSION PERIOD EITHER DIRECTLY OR INDIRECTLY, AS IN THE CASE OF CISPLATIN: FOR THIS CROSS-LINKING AGENT, THE SIGNIFICANT DECREASE IN DNA MIGRATION OBSERVED UNDER STANDARD ELECTROPHORESIS CONDITIONS WAS CLEARLY AMPLIFIED WHEN THE DURATION OF ELECTROPHORESIS WAS INCREASED UP TO 40MIN. IN CONTRAST, EPIGENETIC AND NEPHROTOXIC COMPOUNDS FAILED TO INDUCE ANY SIGNIFCANT INCREASE IN DNA MIGRATION. IN CONCLUSION, THE IN VIVO RODENT COMET ASSAY PERFORMED ON ISOLATED KIDNEY CELLS COULD BE USED AS A TOOL TO INVESTIGATE THE GENOTOXIC POTENTIAL OF A TEST COMPOUND IF NEOPLASIC/PRENEOPLASIC CHANGES OCCUR AFTER SUBCHRONIC OR CHRONIC TREATMENTS, IN ORDER TO DETERMINE THE ROLE OF GENOTOXICITY IN TUMOR INDUCTION. MOREOVER, THE EPIGENETIC CARCINOGENS AND CYTOTOXIC COMPOUNDS DISPLAYED CLEARLY NEGATIVE RESPONSES IN THIS STUDY. THESE RESULTS ALLOW EXCLUDING A DNA DIRECT-ACTING MECHANISM OF ACTION AND CAN THUS SUGGEST THAT A THRESHOLD EXISTS. THEREFORE, THE CURRENT IN VIVO RODENT COMET ASSAY COULD CONTRIBUTE TO ELUCIDATE AN EPIGENETIC MECHANISM AND THUS, TO UNDERTAKE A RISK ASSESSMENT ASSOCIATED WITH HUMAN USE, DEPENDING ON THE EXPOSURE LEVEL. 2007 8 4822 25 OCHRATOXIN A: 50 YEARS OF RESEARCH. SINCE OCHRATOXIN A (OTA) WAS DISCOVERED, IT HAS BEEN UBIQUITOUS AS A NATURAL CONTAMINANT OF MOLDY FOOD AND FEED. THE MULTIPLE TOXIC EFFECTS OF OTA ARE A REAL THREAT FOR HUMAN BEINGS AND ANIMAL HEALTH. FOR EXAMPLE, OTA CAN CAUSE PORCINE NEPHROPATHY BUT CAN ALSO DAMAGE POULTRIES. HUMANS EXPOSED TO OTA CAN DEVELOP (NOTABLY BY INHALATION IN THE DEVELOPMENT OF ACUTE RENAL FAILURE WITHIN 24 H) A RANGE OF CHRONIC DISORDERS SUCH AS UPPER UROTHELIAL CARCINOMA. OTA PLAYS THE MAIN ROLE IN THE PATHOGENESIS OF SOME RENAL DISEASES INCLUDING BALKAN ENDEMIC NEPHROPATHY, KIDNEY TUMORS OCCURRING IN CERTAIN ENDEMIC REGIONS OF THE BALKAN PENINSULA, AND CHRONIC INTERSTITIAL NEPHROPATHY OCCURRING IN NORTHERN AFRICAN COUNTRIES AND LIKELY IN OTHER PARTS OF THE WORLD. OTA LEADS TO DNA ADDUCT FORMATION, WHICH IS KNOWN FOR ITS GENOTOXICITY AND CARCINOGENICITY. THE PRESENT ARTICLE DISCUSSES HOW RENAL CARCINOGENICITY AND NEPHROTOXICITY CAUSE BOTH OXIDATIVE STRESS AND DIRECT GENOTOXICITY. CAREFUL ANALYSES OF THE DATA SHOW THAT OTA CARCINOGENIC EFFECTS ARE DUE TO COMBINED DIRECT AND INDIRECT MECHANISMS (E.G., GENOTOXICITY, OXIDATIVE STRESS, EPIGENETIC FACTORS). ALTOGETHER THIS PROVIDES STRONG EVIDENCE THAT OTA CARCINOGENICITY CAN ALSO OCCUR IN HUMANS. 2016 9 4820 30 OCHRATOXIN A AS A POTENTIAL ETIOLOGIC FACTOR IN ENDEMIC NEPHROPATHY: LESSONS FROM TOXICITY STUDIES IN RATS. VARIOUS REPORTS SUGGEST THAT CHRONIC DIETARY EXPOSURE TO OCHRATOXIN A (OTA), A MYCOTOXIN FREQUENTLY DETECTED IN VARIOUS FOOD ITEMS MAY BE LINKED TO THE PATHOGENESIS OF ENDEMIC NEPHROPATHY, A CHRONIC TUBULOINTERSTITIAL KIDNEY DISEASE WHICH OCCURS IN GEOGRAPHICALLY LIMITED AREAS OF THE BALKAN REGION. OTA IS A POTENT NEPHROTOXIN AND RENAL CARCINOGEN. HOWEVER, THE PATHOLOGICAL LESIONS OBSERVED IN KIDNEYS OF RATS TREATED WITH OTA APPEAR BE RATHER DIFFERENT FROM THE CLINICAL AND PATHOLOGICAL CHARACTERISTICS OF ENDEMIC NEPHROPATHY. MOREOVER, INCREASING EVIDENCE SUGGESTS THAT OTA DOES NOT BIND TO DNA BUT INDUCES TUMORS BY AN EPIGENETIC, THRESHOLDED MECHANISM. THIS IMPLIES THAT THERE IS A DOSE BELOW WHICH NO ADVERSE HEALTH EFFECTS ARE EXPECTED TO OCCUR. BASED ON FOOD CONSUMPTION DATA AND OTA SERUM CONCENTRATIONS, IT APPEARS THAT HUMAN EXPOSURE - EVEN IN AREAS WITH RELATIVELY HIGH DIETARY EXPOSURE TO OTA SUCH AS ENDEMIC VILLAGES - IS SEVERAL ORDERS OF MAGNITUDE BELOW DOSES KNOWN TO CAUSE NEPHROTOXICITY AND TUMOR FORMATION IN LABORATORY ANIMALS. WHILE IT IS UNDOUBTEDLY IMPORTANT TO ENCOURAGE PREVENTION OF FOOD CONTAMINATION BY OTA AND OTHER MYCOTOXINS, THESE OBSERVATIONS SUGGEST THAT OTA IS NOT LIKELY TO BE AN ETIOLOGICAL FACTOR INVOLVED IN BEN AND INDICATE A NEED TO SEARCH FOR NEW CLUES FOR THE ETIOLOGY OF THIS ENDEMIC KIDNEY DISEASE. 2007 10 837 38 CHEMICALLY INDUCED RENAL TUBULE TUMORS IN THE LABORATORY RAT AND MOUSE: REVIEW OF THE NCI/NTP DATABASE AND CATEGORIZATION OF RENAL CARCINOGENS BASED ON MECHANISTIC INFORMATION. THE INCIDENCE OF RENAL TUBULE CARCINOGENESIS IN MALE AND FEMALE RATS OR MICE WITH 69 CHEMICALS FROM THE 513 BIOASSAYS CONDUCTED TO DATE BY THE NCI/NTP HAS BEEN COLLATED, THE CHEMICALS CATEGORIZED, AND THE RELATIONSHIP BETWEEN CARCINOGENESIS AND RENAL TUBULE HYPERPLASIA AND EXACERBATION OF THE SPONTANEOUS, AGE-RELATED RODENT DISEASE CHRONIC PROGRESSIVE NEPHROPATHY (CPN) EXAMINED. WHERE INFORMATION ON MECHANISM OR MODE OF ACTION EXISTS, THE CHEMICALS HAVE BEEN CATEGORIZED BASED ON THEIR ABILITY TO DIRECTLY OR INDIRECTLY INTERACT WITH RENAL DNA, OR ON THEIR ACTIVITY VIA EPIGENETIC PATHWAYS INVOLVING EITHER DIRECT OR INDIRECT CYTOTOXICITY WITH REGENERATIVE HYPERPLASIA, OR EXACERBATION OF CPN. NINE CHEMICALS WERE IDENTIFIED AS DIRECTLY INTERACTING WITH DNA, WITH SIX OF THESE PRODUCING RENAL TUBULE TUMORS AT HIGH INCIDENCE IN RATS OF BOTH SEXES, AND IN SOME CASES ALSO IN MICE. OCHRATOXIN A WAS THE MOST POTENT COMPOUND IN THIS GROUP, PRODUCING A HIGH TUMOR INCIDENCE AT VERY LOW DOSES, OFTEN WITH METASTASIS. THREE CHEMICALS WERE DISCUSSED IN THE CONTEXT OF INDIRECT DNA DAMAGE MEDIATED BY AN OXIDATIVE FREE RADICAL MECHANISM, ONE OF THESE BEING FROM THE NTP DATABASE. A THIRD CATEGORY INCLUDED FOUR CHEMICALS THAT HAD THE POTENTIAL TO CAUSE DNA DAMAGE FOLLOWING CONJUGATION WITH GLUTATHIONE AND SUBSEQUENT ENZYMATIC ACTIVATION TO A REACTIVE SPECIES, USUALLY A THIOL-CONTAINING ENTITY. TWO CHEMICALS WERE ALLOCATED INTO THE CATEGORY INVOLVING A DIRECT CYTOTOXIC ACTION ON THE RENAL TUBULE FOLLOWED BY SUSTAINED COMPENSATORY CELL PROLIFERATION, WHILE NINE WERE INCLUDED IN A GROUP WHERE THE CELL LOSS AND SUSTAINED INCREASE IN RENAL TUBULE CELL TURNOVER WERE DEPENDENT ON LYSOSOMAL ACCUMULATION OF THE MALE RAT-SPECIFIC PROTEIN, ALPHA2MU-GLOBULIN. IN A SIXTH CATEGORY, MORPHOLOGIC EVIDENCE ON TWO CHEMICALS INDICATED THAT THE RENAL TUMORS WERE A CONSEQUENCE OF EXACERBATED CPN. FOR THE REMAINING CHEMICALS, THERE WERE NO PERTINENT DATA ENABLING ASSIGNMENT TO A MECHANISTIC CATEGORY. ACCORDINGLY, THESE CHEMICALS, ACTING THROUGH AN AS YET UNKNOWN MECHANISM, WERE GROUPED AS EITHER BEING ASSOCIATED WITH AN ENHANCEMENT OF CPN (CATEGORY 7, 16 CHEMICALS), OR NOT ASSOCIATED WITH ENHANCED CPN (CATEGORY 8, 4 CHEMICALS). A NINTH CATEGORY DEALT WITH 11 CHEMICALS THAT WERE REGARDED AS PRODUCING INCREASES IN RENAL TUBULE TUMORS THAT DID NOT REACH STATISTICAL SIGNIFICANCE. A 10TH CATEGORY DISCUSSED 6 CHEMICALS THAT INDUCED RENAL TUMORS IN MICE BUT NOT IN RATS, PLUS 8 CHEMICALS THAT PRODUCED A LOW INCIDENCE OF RENAL TUBULE TUMORS IN MICE THAT DID NOT REACH STATISTICAL SIGNIFICANCE. AS MORE MECHANISTIC DATA ARE GENERATED, SOME CHEMICALS WILL INEVITABLY BE PLACED IN DIFFERENT GROUPS, PARTICULARLY THOSE FROM CATEGORIES 7 AND 8. A LARGE NUMBER OF CHEMICALS IN THE SERIES EXACERBATED CPN, BUT THOSE IN CATEGORY 7 ESPECIALLY MAY BE CANDIDATES FOR INCLUSION IN CATEGORY 6 WHEN FURTHER INFORMATION IS GLEANED FROM THE RELEVANT NTP STUDIES. ALSO, NEW DATA ON SPECIFIC CHEMICALS WILL PROBABLY EXPAND CATEGORY 5 AS CYTOTOXICITY AND CELL REGENERATION ARE IDENTIFIED AS OBLIGATORY STEPS IN RENAL CARCINOGENESIS IN MORE CASES. ADDITIONAL CONFIRMATORY OUTCOMES ARISING FROM THIS REVIEW ARE THAT METASTASES FROM RENAL TUBULE TUMORS, WHILE ENCOUNTERED WITH CHEMICALS CAUSING DNA DAMAGE, ARE RARE WITH THOSE ACTING THROUGH AN EPIGENETIC PATHWAY, WITH THE EXCEPTION BEING FUMONISIN B1; THAT MALE RATS AND MICE ARE GENERALLY MORE SUSCEPTIBLE THAN FEMALE RATS AND MICE TO CHEMICAL INDUCTION OF RENAL TUBULE TUMORS; AND THAT A BACKGROUND OF ATYPICAL TUBULE HYPERPLASIA IS A USEFUL INDICATOR REFLECTING A CHEMICALLY ASSOCIATED RENAL TUBULE TUMOR RESPONSE. WITH RESPECT TO RENAL TUBULE TUMORS AND HUMAN RISK ASSESSMENT, CHEMICALS IN CATEGORIES 1 AND 2, AND POSSIBLY 3, WOULD CURRENTLY BE JUDGED BY LINEAR DEFAULT METHODS; CHEMICALS IN CATEGORY 4 (AND PROBABLY SOME IN CATEGORY 3) AS EXHIBITING A THRESHOLD OF ACTIVITY WARRANTING THE BENCHMARK APPROACH; AND THOSE IN CATEGORIES 5 AND 6 AS REPRESENTING MECHANISMS THAT HAVE NO RELEVANCE FOR EXTRAPOLATION TO HUMANS. 2004 11 4824 26 OCHRATOXIN A: THE CONTINUING ENIGMA. THE MYCOTOXIN OCHRATOXIN A (OTA) HAS BEEN LINKED TO THE GENESIS OF SEVERAL DISEASE STATES IN BOTH ANIMALS AND HUMANS. IT HAS BEEN DESCRIBED AS NEPHROTOXIC, CARCINOGENIC, TERATOGENIC, IMMUNOTOXIC, AND HEPATOTOXIC IN LABORATORY AND DOMESTIC ANIMALS, AS WELL AS BEING THOUGHT TO BE THE PROBABLE CAUSAL AGENT IN THE DEVELOPMENT OF NEPHROPATHIES (BALKAN ENDEMIC NEPHROPATHY, BEN AND CHRONIC INTERSTITIAL NEPHROPATHY, CIN) AND UROTHELIAL TUMORS IN HUMANS. AS A RESULT, SEVERAL INTERNATIONAL AGENCIES ARE CURRENTLY ATTEMPTING TO DEFINE SAFE LEGAL LIMITS FOR OTA CONCENTRATION IN FOODSTUFFS (E.G., GRAIN, MEAT, WINE, AND COFFEE), IN PROCESSED FOODS, AND IN ANIMAL FODDER. IN ORDER TO ACHIEVE THIS GOAL, AN ACCURATE RISK ASSESSMENT OF OTA TOXICITY INCLUDING MECHANISTIC AND EPIDEMIOLOGICAL STUDIES MUST BE CARRIED OUT. OCHRATOXIN HAS BEEN SUGGESTED BY VARIOUS RESEARCHERS TO MEDIATE ITS TOXIC EFFECTS VIA INDUCTION OF APOPTOSIS, DISRUPTION OF MITOCHONDRIAL RESPIRATION AND/OR THE CYTOSKELETON, OR, INDEED, VIA THE GENERATION OF DNA ADDUCTS. THUS, IT IS STILL UNCLEAR IF THE PREDOMINANT MECHANISM IS OF A GENOTOXIC OR AN EPIGENETIC NATURE. ONE ASPECT THAT IS CLEAR, HOWEVER, IS THAT THE TOXICITY OF OTA IS SUBJECT TO AND CHARACTERIZED BY LARGE SPECIES- AND SEX-SPECIFIC DIFFERENCES, AS WELL AS AN APPARENTLY STRICT STRUCTURE-ACTIVITY RELATIONSHIP. THESE CONSIDERATIONS COULD BE CRUCIAL IN THE INVESTIGATION OF OTA-MEDIATED TOXICITY. FURTHERMORE, THE USE OF APPROPRIATE IN VIVO AND IN VITRO MODEL SYSTEMS APPEARS TO BE VITAL IN THE GENERATION OF RELEVANT EXPERIMENTAL DATA. THE INTENTION OF THIS REVIEW IS TO COLLATE AND DISCUSS THE CURRENTLY AVAILABLE DATA ON OTA-MEDIATED TOXICITY WITH PARTICULAR FOCUS ON THEIR RELEVANCE FOR THE IN VIVO SITUATION, AND ALSO TO SUGGEST POSSIBLE FUTURE STRATEGIES FOR UNLOCKING THE SECRETS OF OCHRATOXIN A. 2005 12 1358 21 DEVELOPMENT OF RATIOMETRIC ELECTROCHEMICAL MOLECULAR SWITCHES TO ASSAY ENDOGENOUS FORMALDEHYDE IN LIVE CELLS, WHOLE BLOOD AND CREATININE IN SALIVA. FORMALDEHYDE IS A REACTIVE CARBONYL SPECIES (RCS) THAT IS PRODUCED NATURALLY IN THE HUMAN BODY VIA METABOLIC AND EPIGENETIC BIOCHEMICAL PROCESSES, YET IN HIGH CONCENTRATIONS IS HIGHLY TOXIC TO THE ENVIRONMENT AS WELL AS TO LIVING ORGANISMS. THEREFORE, WE DESIGNED TWO RATIOMETRIC ELECTROCHEMICAL MOLECULAR REDOX PROBES, FORMALDEHYDE OXIDATIVE LATENT PROBE (FOLP) AND DIHYDROXY-FORMALDEHYDE OXIDATIVE LATENT PROBE (HFOLP), FOR THE SELECTIVE PROFILING OF ENDOGENOUS FORMALDEHYDE. FOLP AND HFOLP EACH UNDERWENT THE AZA-COPE REACTION WITH FORMALDEHYDE FOLLOWED BY HYDROLYSIS TO ELIMINATE UNMASK REDOX REPORTER N-ALKYLATED AMINOFERROCENE (AAF) TO MONITOR THEIR RESPONSE CURRENT. THE FOLP AND HFOLP SENSORS SHOWED BROAD DYNAMIC RANGES OF 0.12-1000 MUM AND 0.09-3 MM FOR FORMALDEHYDE WITH DETECTION LIMITS OF 48.2 NM AND 31.6 MUM, RESPECTIVELY. ALSO, SINCE FORMALDEHYDE IS THE BYPRODUCT OF BIOCHEMICAL REACTIONS FOR DETECTING CREATININE AND CREATININE IS AN IMPORTANT BIOMARKER FOR CHRONIC KIDNEY DISEASE (CKD), WE TESTED THE FOLP PROBE FOR ITS ABILITY TO MONITOR CREATININE. IT SUCCESSFULLY DID SO, AND THIS ABILITY WAS USED TO DEVELOP AN ELECTROCHEMICAL PLATFORM FOR THE QUANTIFICATION OF CREATININE; IT SHOWED A DYNAMIC RANGE OF 3.25-200 MUM AND A LIMIT OF DETECTION (1.3 MUM). IN ADDITION, THE FOLP-BASED ASSAY PLATFORM DELIVERED A RELIABLE ANALYTICAL PERFORMANCE FOR THE QUANTIFICATION OF FORMALDEHYDE IN HUMAN WHOLE BLOOD AND OF CREATININE IN SALIVA, AND ALSO FOR THE REAL-TIME MONITORING OF ENDOGENOUS FORMALDEHYDE SECRETION IN HELA CELLS. MOREOVER, THE CONCENTRATIONS DETERMINED USING OUR METHOD WERE FOUND TO BE CONSISTENT WITH THOSE DETERMINED USING FORMALDEHYDE AND CREATININE FLUOROMETRIC ASSAY KITS. 2021 13 818 22 CHARACTERISTICS OF THE SPECTRUM OF PROLIFERATIVE LESIONS OBSERVED IN THE KIDNEY AND URINARY BLADDER OF FISCHER 344 RATS AND B6C3F1 MICE. MANY RODENT RENAL AND BLADDER CARCINOGENS RELY UPON EPIGENETIC MECHANISMS OF CARCINOGENESIS; SUCH MECHANISMS ARE LIKELY TO INFLUENCE THE SPECTRUM OF URINARY TRACT TUMORS OBSERVED IN CONTROL AND TREATED ANIMALS. THIS IS REFLECTED IN SEVERAL FEATURES OF CHEMICALLY INDUCED RODENT URINARY TRACT NEOPLASMS, INCLUDING A LOW OVERALL TUMOR INCIDENCE, AN INCREASED PREVALENCE OF URINARY TRACT TUMORS IN RATS COMPARED TO MICE AND MALES COMPARED TO FEMALES, THE TENDENCY FOR EPITHELIAL TUMORS TO PREDOMINATE OVER NONEPITHELIAL TYPES, AND DEMONSTRATED LINKS TO CHRONIC PROGRESSIVE NEPHROPATHY AND UROLITHIASIS. SUCH TENDENCIES ARE ALSO CHARACTERISTIC OF SPONTANEOUS URINARY TRACT TUMORS IN RODENTS. DATA TO SUPPORT THESE OBSERVATIONS CAN BE DERIVED FROM LARGE HISTORICAL DATABASES SUCH AS THE TOXICOLOGY DATA MANAGEMENT SYSTEM, MAINTAINED BY NATIONAL TOXICOLOGY PROGRAM. 2002 14 3267 20 HEPATOCELLULAR CARCINOMA AND POSSIBLE CHEMICAL AND BIOLOGICAL CAUSES: A REVIEW. THE DEVELOPMENT OF HEPATOCELLULAR CARCINOMA (HCC) IS A MULTISTEP PROCESS. IN HCC, PROGRESSIVE AND MORPHOLOGICALLY DISTINCT PRENEOPLASTIC LESIONS/ALTERATIONS ASSOCIATED WITH CHRONIC LIVER INJURY, INFLAMMATION, HEPATOCELLULAR DEGENERATION/REGENERATION, NECROSIS, AND SMALL-CELL DYSPLASIA CAN BE OBSERVED. THE INCIDENCE OF HCC EXHIBITS REGIONAL AND ETHNIC DIFFERENCES. SEVERAL CYTOTOXIC AND DNA-DAMAGING CHEMICALS ARE SUGGESTED TO BE THE UNDERLYING CAUSES OF HCC-FOR EXAMPLE, ACRYLAMIDE, PERFLUOROOCTANOIC ACID (PFOA), POLYCHLORINATED BIPHENYLS (PCBS), BENZO(A)PYRENE (BAP), PERFLUORINATED CHEMICALS (PFCS), VINYL CHLORIDE MONOMER (VCM), AND DIETARY CONTAMINANTS (AFLATOXINS, OCHRATOXINS). ALSO SUGGESTED ARE SUBSTANCES OF ABUSE (ALCOHOL) AND BIOLOGICAL AGENTS, SUCH AS HEPATITIS B AND C AND HUMAN IMMUNODEFICIENCY VIRUS 1 (HIV-1). THESE CAN ACT THROUGH GENETIC AND/OR EPIGENETIC MECHANISMS. THIS REVIEW WILL SHORTLY ADDRESS THE GENETIC AND EPIGENETIC MECHANISMS OF HCC AND FOCUS ON CYTOTOXIC AND DNA-DAMAGING CHEMICALS AND BIOLOGICAL AGENTS, EXPOSURE TO WHICH ARE SUGGESTED TO LEAD TO HCC INITIATION, PROMOTION, AND/OR PROGRESSION. 2017 15 5100 34 POLYCHLORINATED BIPHENYLS (PCBS) ALTER DNA METHYLATION AND GENOMIC INTEGRITY OF SHEEP FETAL CELLS IN A SIMPLIFIED IN VITRO MODEL OF PREGNANCY EXPOSURE. POLYCHLORINATED BIPHENYLS (PCBS) ARE PERSISTENT ORGANIC POLLUTANTS UBIQUITOUSLY DETECTABLE IN THE ENVIRONMENT AND IN THE FOOD CHAIN. PRENATAL EXPOSURE TO PCBS NEGATIVELY AFFECTS FETAL DEVELOPMENT AND PRODUCES LONG-TERM DETRIMENTAL EFFECTS ON CHILD HEALTH. THE PRESENT STUDY SOUGHT TO EVALUATE THE CYTOTOXIC AND GENOTOXIC EFFECTS OF CHRONIC PCB EXPOSURE ON FETAL CELLS DURING PREGNANCY. TO THIS AIM, SHEEP EMBRYONIC FIBROBLASTS (SEF) AND AMNIOCYTES (SA) WERE CULTURED IN VITRO IN THE PRESENCE OF LOW DOSES OF PCBS FOR A PERIOD OF 120DAYS, COMPARABLE TO THE FULL TERM OF OVINE PREGNANCY. CELLULAR PROLIFERATION RATES, GLOBAL DNA METHYLATION, CHROMOSOME INTEGRITY, AND MARKERS OF DNA DAMAGE WERE EVALUATED AT DIFFERENT TIME POINTS. MOREOVER, SEF TREATED WITH PCBS FOR 60DAYS WERE LEFT UNTREATED FOR ONE FURTHER MONTH AND THEN EXAMINED IN ORDER TO EVALUATE THE REVERSIBILITY OF PCB-INDUCED EPIGENETIC DEFECTS. PCB-TREATED SEF WERE MORE SENSITIVE THAN SA TREATED WITH PCBS, IN TERMS OF LOW CELL PROLIFERATION, AND INCREASED DNA DAMAGE AND GLOBAL DNA METHYLATION, WHICH WERE STILL DETECTABLE AFTER INTERRUPTION OF PCB TREATMENT. THESE DATA INDICATE THAT CHRONIC EXPOSURE OF FETAL CELLS TO PCBS CAUSES PERMANENT GENOMIC AND EPIGENETIC INSTABILITY, WHICH MAY INFLUENCE BOTH PRENATAL AND POST-NATAL GROWTH UP TO ADULTHOOD. OUR IN VITRO MODEL OFFER A SIMPLE AND CONTROLLED MEANS OF STUDYING THE EFFECTS OF DIFFERENT CONTAMINANTS ON FETAL CELLS - ONE THAT COULD SET THE STAGE FOR TARGETED IN VIVO STUDIES. 2018 16 4123 32 MECHANISMS OF DIMETHYLBENZANTHRACENE-INDUCED IMMUNOTOXICITY. TRADITIONAL METHODS FOR TOXICOLOGICAL ASSESSMENT HAVE IMPLICATED THE IMMUNE SYSTEM AS A FREQUENT TARGET ORGAN OF TOXIC INSULT FOLLOWING CHRONIC EXPOSURE TO CERTAIN ENVIRONMENTAL CHEMICALS, RADIATION OR THERAPEUTIC DRUGS (XENOBIOTICS). IMMUNOTOXICITY IS EXPRESSED AS AUTOIMMUNITY, CHEMICAL HYPERSENSITIVITY OR IMMUNOSUPPRESSION. A TIERED APPROACH FOR CHARACTERIZING CHEMICAL AND DRUG-INDUCED IMMUNOMODULATION HAS BEEN DEVELOPED AND VALIDATED IN LABORATORY ANIMALS. POLYCYCLIC AROMATIC HYDROCARBONS (PAH) HAVE BEEN STUDIED BECAUSE OF THEIR UBIQUITOUS PRESENCE IN THE ENVIRONMENT AND CARCINOGENIC POTENTIAL. SINCE IMMUNOSUPPRESSION INDUCED BY PAH CARCINOGENS HAS BEEN IMPLICATED AS AN EPIGENETIC MECHANISM IN THE OUTGROWTH OF INITIATED CELLS, THIS TIERED APPROACH WAS USED TO CHARACTERIZE THE MECHANISM OF PAH IMMUNOSUPPRESSIVE CAPACITY. PREVIOUSLY, STUDIES IN THIS LABORATORY HAVE DEMONSTRATED THAT SUBCHRONIC EXPOSURE OF B6C3F1 MICE TO PAH CARCINOGENS SUPPRESSES BOTH HUMORAL IMMUNITY (HI) AND CELL-MEDIATED IMMUNITY (CMI), CONCURRENTLY WITH DECREASED RESISTANCE TO TUMOR CHALLENGE. THE POTENT CARCINOGENIC PAH, 7,12-DIMETHYLBENZ[A]ANTHRACENE (DMBA) WAS SUBCHRONICALLY ADMINISTERED SUBCUTANEOUSLY AT 5, 50, OR 100 MICROGRAMS/G OF BODY WEIGHT. NATURAL KILLER (NK) CELL TUMOR CYTOLYSIS, GENERATION OF CYTOTOXIC T-CELLS (CTL), AND LYMPHOPROLIFERATION TO MITOGENS AND ALLOGENEIC SPLENOCYTES IN MIXED LEUKOCYTE CULTURES (MLC) WERE QUANTITATED 3-5 DAYS AFTER EXPOSURE TO ASSESS CMI. MITOGEN AND ALLOANTIGEN-INDUCED PROLIFERATION (MLC) OF SPLENOCYTES WAS SUPPRESSED UP TO 90%. CTL AND NK TUMOR CYTOLYSIS OF RADIOLABELLED TARGET CELLS WERE SIMILARLY DEPRESSED UP TO 88 AND 82%, RESPECTIVELY. IMPAIRMENT OF MLC OR CTL RESPONSES CORRELATED WITH INCREASED SUSCEPTIBILITY TO CHALLENGE WITH PYB6 SARCOMA CELLS. HI WAS MEASURED BY QUANTITATING THE NUMBER OF ANTIBODY (IGM) PLAQUE-FORMING CELLS (PFC) PRODUCED IN RESPONSE TO T-CELL DEPENDENT ANTIGEN CHALLENGE (SHEEP ERYTHROCYTES) AND WAS SIMILARLY SUPPRESSED UP TO 95%. TO UNDERSTAND THE MECHANISM OF PAH-INDUCED IMMUNOTOXICITY, SPLENOCYTES FROM DMBA-EXPOSED MICE WERE SENSITIZED TO ALLOANTIGENS IN THE PRESENCE OF INTERLEUKIN-2 (IL-2) BECAUSE THERE WERE INDICATIONS THAT T-HELPER CELL FUNCTION WAS SUPPRESSED. IN THESE PRELIMINARY STUDIES, CTL SUPPRESSION COULD BE COMPLETELY RESTORED BY THE ADDITION OF THE T-CELL GROWTH SUPPORTING LYMPHOKINE (IL-2) DURING THE INDUCTIVE PHASE OF CTL GENERATION, SUGGESTING THAT DMBA EXPOSURE DIRECTLY OR INDIRECTLY INDUCED DEFICITS IN T-HELPER CELL FUNCTION. 1985 17 2838 21 FORMALDEHYDE CARCINOGENICITY RESEARCH: 30 YEARS AND COUNTING FOR MODE OF ACTION, EPIDEMIOLOGY, AND CANCER RISK ASSESSMENT. FORMALDEHYDE IS A WIDELY USED HIGH PRODUCTION CHEMICAL THAT IS ALSO RELEASED AS A BYPRODUCT OF COMBUSTION, OFF-GASSING OF VARIOUS BUILDING PRODUCTS, AND AS A FIXATIVE FOR PATHOLOGISTS AND EMBALMERS. WHAT IS NOT OFTEN REALIZED IS THAT FORMALDEHYDE IS ALSO PRODUCED AS A NORMAL PHYSIOLOGIC CHEMICAL IN ALL LIVING CELLS. IN 1980, CHRONIC INHALATION OF HIGH CONCENTRATIONS OF FORMALDEHYDE WAS SHOWN TO BE CARCINOGENIC, INDUCING A HIGH INCIDENCE OF NASAL SQUAMOUS CELL CARCINOMAS IN RATS. SOME EPIDEMIOLOGIC STUDIES HAVE ALSO FOUND INCREASED NUMBERS OF NASOPHARYNGEAL CARCINOMA AND LEUKEMIA IN HUMANS EXPOSED TO FORMALDEHYDE THAT RESULTED IN FORMALDEHYDE BEING CONSIDERED A KNOWN HUMAN CARCINOGEN. THIS ARTICLE REVIEWS THE DATA FOR RODENT AND HUMAN CARCINOGENICITY, EARLY MODE OF ACTION STUDIES, MORE RECENT MOLECULAR STUDIES OF BOTH ENDOGENOUS AND EXOGENOUS DNA ADDUCTS, AND EPIGENETIC STUDIES. IT GOES ON TO DEMONSTRATE THE POWER OF THESE RESEARCH STUDIES TO PROVIDE CRITICAL DATA TO IMPROVE OUR ABILITY TO DEVELOP SCIENCE-BASED CANCER RISK ASSESSMENTS, INSTEAD OF DEFAULT APPROACHES. THE COMPLEXITY OF CONSTANT PHYSIOLOGIC EXPOSURE TO A KNOWN CARCINOGEN REQUIRES THAT NEW WAYS OF THINKING BE INCORPORATED INTO DETERMINATIONS OF CANCER RISK ASSESSMENT FOR FORMALDEHYDE, OTHER ENDOGENOUS CARCINOGENS, AND THE ROLE OF BACKGROUND ENDOGENOUS DNA DAMAGE AND MUTAGENESIS. 2013 18 86 25 A PATERNAL HYPERCALORIC DIET AFFECTS THE METABOLISM AND FERTILITY OF F1 AND F2 WISTAR RAT GENERATIONS. INCREASED FAT AND CARBOHYDRATE INTAKES BASED ON THE WESTERN DIET ARE IMPORTANT LIFESTYLE MODIFICATIONS THAT LEAD TO HYPERCALORIC INPUTS, OBESITY, AND MALE FERTILITY NEGATIVE EFFECTS. EPIGENETIC TRANSMISSION MAY ALSO PREDISPOSE DESCENDED GENERATIONS TO CHRONIC DISEASES, SUCH AS OBESITY, TYPE 2 DIABETES, BEHAVIORAL, AND REPRODUCTIVE DISORDERS. THE PRESENT STUDY SOUGHT TO EVALUATE THE INFLUENCE OF A HIGH-FAT-HIGH-SUGAR (HFHS) DIET SUPPLIED TO WISTAR RATS FROM 25 TO 90 DAYS OF LIFE ON REPRODUCTIVE AND METABOLIC PARAMETERS IN MALE GENERATIONS F0, F1, AND F2. THE STANDARD GROUP RECEIVED THE NORMOCALORIC - NUVILAB QUIMTIA(R) -3.86 KCAL/KG. THE HYPERCALORIC DIET (HD) GROUP RECEIVED THE HFHS DIET - PRAGSOLUCOES(R) -4.77 KCAL/KG. BODY WEIGHT, ADIPOSITY, F1 AND F2 PREPUBERTAL AGE EVALUATIONS, ORAL GLUCOSE TOLERANCE TEST, INSULIN TOLERANCE TEST, ORGAN WEIGHTS, SPERM COUNT AND MORPHOLOGY ASSESSMENTS, AND HISTOMETRIC TESTICULAR ANALYSES WERE PERFORMED. THE HFHS DIET PROMOTED DYSLIPIDEMIA, HIGHER ADIPOSITY, LOWER RELATIVE ORGAN WEIGHTS, AND HIGHER MEAN KIDNEY WEIGHT, DECREASED MEAN TESTICLE AND PARENCHYMA WEIGHTS AND LOWER HEIGHT OF SEMINIFEROUS EPITHELIUM (HE) FOR THE F0 GENERATION. F1 AND F2 OFFSPRING OF HD GROUP DISPLAYED EARLY PREPREPUBERTAL DEVELOPMENT, ALTHOUGH DID NOT ALTER THE METABOLIC PARAMETERS. DECREASED HE AND TUBULAR TESTICULAR COMPARTMENT VOLUMETRIC DENSITY AND INCREASED INTERTUBULAR TESTICULAR COMPARTMENT VOLUMETRIC DENSITY AND VOLUME IN THE F1 GENERATION OF HD GROUP WERE OBSERVED. ALTERATIONS IN HISTOMETRY OF INTERTUBULAR TESTICULAR COMPARTMENT WERE ALSO NOTED. IT IS CONCLUDED THAT THE HFHS EXPERIMENTAL MODEL ALTERED ONLY PATERNAL METABOLIC PARAMETERS. HOWEVER, REPRODUCTIVE PARAMETERS OF THE THREE GENERATIONS WERE AFFECTED. 2020 19 1980 28 EPIGENETIC ALTERATIONS IN CYTOCHROME P450 OXIDOREDUCTASE (POR) IN SPERM OF RATS EXPOSED TO TETRAHYDROCANNABINOL (THC). AS MARIJUANA LEGALIZATION IS INCREASING, RESEARCH REGARDING POSSIBLE LONG-TERM RISKS FOR USERS AND THEIR OFFSPRING IS NEEDED. LITTLE DATA EXISTS ON EFFECTS OF PATERNAL TETRAHYDROCANNABINOL (THC) EXPOSURE PRIOR TO REPRODUCTION. THIS STUDY DETERMINED IF CHRONIC THC EXPOSURE ALTERS SPERM DNA METHYLATION (DNAM) AND IF SUCH EFFECTS ARE INTERGENERATIONALLY TRANSMITTED. ADULT MALE RATS UNDERWENT ORAL GAVAGE WITH THC OR VEHICLE CONTROL. DIFFERENTIALLY METHYLATED (DM) LOCI IN MOTILE SPERM WERE IDENTIFIED USING REDUCED REPRESENTATION BISULFITE SEQUENCING (RRBS). ANOTHER COHORT WAS INJECTED WITH VEHICLE OR THC, AND SPERM DNAM WAS ANALYZED. FINALLY, THC-EXPOSED AND CONTROL ADULT MALE RATS WERE MATED WITH THC-NAIVE FEMALES. DNAM LEVELS OF TARGET GENES IN BRAIN TISSUES OF THE OFFSPRING WERE DETERMINED BY PYROSEQUENCING. RRBS IDENTIFIED 2,940 DM CPGS MAPPING TO 627 GENES. SIGNIFICANT HYPERMETHYLATION WAS CONFIRMED (P < 0.05) FOLLOWING ORAL THC ADMINISTRATION FOR CYTOCHROME P450 OXIDOREDUCTASE (POR), INVOLVED IN TOXIN PROCESSING AND DISORDERS OF SEXUAL DEVELOPMENT. POR HYPERMETHYLATION WAS NOT OBSERVED AFTER THC INJECTION OR IN THE SUBSEQUENT GENERATION. THESE RESULTS SUPPORT THAT THC ALTERS DNAM IN SPERM AND THAT ROUTE OF EXPOSURE CAN HAVE DIFFERENTIAL EFFECTS. ALTHOUGH WE DID NOT OBSERVE EVIDENCE OF INTERGENERATIONAL TRANSMISSION OF THE DNAM CHANGE, LARGER STUDIES ARE REQUIRED TO DEFINITIVELY EXCLUDE THIS POSSIBILITY. 2020 20 835 27 CHEMICAL CARCINOGEN MECHANISMS OF ACTION AND IMPLICATIONS FOR TESTING METHODOLOGY. CHEMICAL CARCINOGENS ARE OF TWO DISTINCT TYPES, DNA-REACTIVE AND EPIGENETIC. TESTING METHODOLOGY CAN BE DIRECTED TOWARD DETECTING EFFECTS OF BOTH TYPES OF CARCINOGEN. CARCINOGENS OF THE DNA-REACTIVE TYPE ARE DEFINED BY THE FORMATION OF COVALENTLY BOUND DNA ADDUCTS. THESE CHEMICALS HAVE STRUCTURES THAT YIELD ELECTROPHILIC REACTANTS EITHER DIRECTLY OR AFTER BIOACTIVATION. THESE AGENTS CAUSE GENOMIC ALTERATION IN THE STRUCTURE OR FUNCTION OF DNA IN THE TARGET CELL. IN ADDITION, THESE COMPOUNDS CAN EXERT OTHER CELLULAR AND TISSUE EPIGENETIC EFFECTS, SUCH AS CELL PROLIFERATION AND GROWTH PROMOTION. CARCINOGENS OF THE EPIGENETIC (PARAGENETIC) TYPE, IN CONTRAST, DO NOT REACT WITH DNA, BUT RATHER DISPLAY CELLULAR EFFECTS SUCH AS NEOPLASM GROWTH PROMOTION, CYTOTOXICITY, INHIBITION OF TISSUE GROWTH REGULATION, PEROXISOME PROLIFERATION, ENDOCRINE MODIFICATION, IMMUNOSUPPRESSION AND/OR SUSTAINED TISSUE ISCHEMIA THAT CAN BE THE BASIS FOR INCREASES IN NEOPLASIA. THEIR CHEMICAL STRUCTURE IS SUCH THAT THEY DO NOT GIVE RISE TO A REACTIVE ELECTROPHILE. THE TESTING METHODOLOGIES TO IDENTIFY EITHER TYPE FOLLOW A DECISION POINT APPROACH DESIGNED TO IDENTIFY POTENTIAL CARCINOGENICITY AND YIELD MECHANISTIC INFORMATION ON THE PRODUCTION OF EFFECTS THAT UNDERLIE CARCINOGENICITY. IT HAS 5 STAGES FOCUSING ON THE CHEMICAL STRUCTURE, DNA-REACTIVITY, EPIGENETIC EFFECTS, LIMITED BIOASSAYS AND FINALLY THE APPLICATION OF THE ACCELERATED BIOASSAY (ABA). ABA REQUIRES 40 WEEKS AND APPLIES THE USE OF SENSITIVE MARKERS FOR INDUCTION OF NEOPLASIA IN COMPARISON TO POSITIVE CONTROL COMPOUNDS FOR IMPORTANT ORGANS IN HUMAN CARCINOGENESIS. IT ENABLES DATA ACQUISITION OF THE ENTIRE CARCINOGENIC PROCESS DIRECTED TOWARD DEVELOPING MECHANISTIC INFORMATION. THE ABA HAS THE POTENTIAL TO REPLACE THE CHRONIC BIOASSAY IN RODENTS IN SOME CIRCUMSTANCES AND CAN SERVE AS AN ALTERNATIVE TO A CHRONIC BIOASSAY IN A SECOND SPECIES. 1996