Anesthesia management of laparoscopic right colectomy in an older patient with postoperative tetralogy of Fallot with residual anomaly.

BACKGROUND: Diversity in hemodynamics of adult congenital heart disease necessitates a case-by-case selection of appropriate surgical and anesthetic options. However, previous case reports regarding the management of laparoscopic surgery in adult patients with congenital heart disease are limited. CASE PRESENTATION: A 72-year-old man who underwent a laparoscopic right colectomy for colon cancer had a residual ventricular septal defect and right ventricular outflow tract obstruction despite post-repair of tetralogy of Fallot. Pulmonary hypertension or right ventricular dysfunction was not observed. The preoperative pulmonary to systemic blood flow ratio (Qp/Qs) was 2.3. After positive pressure ventilation and insufflation, the amount of left-to-right ventricular shunting decreased, and the Qp/Qs approached 1.0, as calculated from pulmonary arterial and systemic arterial blood gas analysis. CONCLUSIONS: Laparoscopic surgery might be tolerable in patients with tetralogy of Fallot who have preserved the right ventricular function, left-to-right ventricular shunting, and no high pulmonary vascular resistance.

Young female participants show blunted placebo effects associated with blunted responses to a cue predicting a safe stimulus in the right dorsolateral prefrontal cortex.

Discrimination of cues predicting non-nociceptive/nociceptive stimuli is essential for predicting whether a non-painful or painful stimulus will be administered and for eliciting placebo/nocebo (pain reduction/pain enhancement) effects. Dysfunction of the neural system involved in placebo effects has been implicated in the pathology of chronic pain, while female sex is one of the important risk factors for development of chronic pain in young adults. The dorsolateral prefrontal cortex (dl-PFC) is suggested to be involved in placebo effects and is sensitive to sex and age. In this study, to examine the neural mechanisms by which sex and age alter placebo and nocebo effects, we analyzed cerebral hemodynamic activities in the dl-PFC in different sex and age groups during a differential conditioning task. During the training session, two different sounds were followed by low- and high-intensity electrical shocks. In the following recording session, electrical shocks, the intensity of which was mismatched to the sounds, were occasionally administered to elicit placebo and nocebo effects. In young female participants, both placebo effects and hemodynamic responses to the conditioned sounds in the right dl-PFC were significantly lower than those in elderly female participants, while there were no age differences in male participants. The hemodynamic responses to the sound paired with the safe stimulus in the right dl-PFC were significantly correlated with placebo effects, except in the young female group. These results suggest that blunted placebo effects in the young female participants are ascribed to blunted responses to the sound associated with the safe stimulus in the right dl-PFC, and that sex- and age-related factors may alter the responsiveness of the right dl-PFC to associative cues predicting a safe stimulus.

Impaired hemodynamic activity in the right dorsolateral prefrontal cortex is associated with impairment of placebo analgesia and clinical symptoms in postherpetic neuralgia.

The dorsolateral prefrontal cortex (dlPFC) is functionally linked to the descending pain modulation system and has been implicated in top down pain inhibition, including placebo analgesia. Therefore, functions of the dlPFC may be impaired in patients with chronic pain. Postherpetic neuralgia (PHN) is one of several syndromes with chronic neuropathic pain. In the present study, we investigated possible dysfunction of the dlPFC in chronic pain using patients with PHN. In a conditioning phase, heathy controls (n = 15) and patients with PHN (n = 7) were exposed to low (LF) and high (HF) frequency tones associated with noxious stimuli: weak (WS) and strong (SS) electrical stimulation, respectively. After the conditioning, cerebral hemodynamic activity was recorded from the bilateral dlPFC while the subjects were subjected to the cue tone-noxious electrical stimulation paradigm, in which incorrectly cued noxious stimuli were sometimes delivered to induce placebo and nocebo effects. The results indicated that hemodynamic responses to the LF tone in the right dlPFC was significantly lower in patients with PHN compared to the healthy controls. Furthermore, the same hemodynamic responses in the right dlPFC were correlated with placebo effects. In addition, clinical symptoms of PHN were negatively correlated to cerebral hemodynamic responses in the right dlPFC and magnitudes of the placebo effects. The results suggest that the right dlPFC, which is closely associated with the descending pain modulation system, is disturbed in PHN.

Relationships Between Intraoperative Hemodynamic Parameters and Delayed Hemodynamic Recovery After Valve Deployment in Transcatheter Aortic Valve Replacement.

OBJECTIVE: To determine the relationships between intraoperative hemodynamic parameters and delayed hemodynamic recovery after valve deployment and identify the predictive factors of delayed hemodynamic recovery by focusing on intraoperative hemodynamics in patients with transcatheter aortic valve replacement (TAVR). DESIGN: A retrospective study. SETTING: A single university hospital. PARTICIPANTS: Sixty-four patients who underwent elective TAVR between 2015 and 2017. INTERVENTIONS: No intervention. MEASUREMENTS AND MAIN RESULTS: The 64 patients were divided into the following 2 groups according to the time for recovery: systolic arterial pressure exceeded 90 mmHg and central venous oxygen saturation (ScvO2) exceeded 65%-delayed recovery (DR) (n = 36) group, and early recovery (ER) (n = 28) group. ScvO2 in the DR group was not lower than that in the ER group after induction of anesthesia. However, ScvO2 in the DR group gradually decreased and was lower than that in the ER group before valve deployment, despite improvement in blood pressure through the administration of vasopressor agents. CONCLUSION: ScvO2 monitoring during TAVR is useful to predict delayed recovery greater than 60 seconds after valve deployment in TAVR.

A choroid plexus cyst in the fourth ventricle of a Sprague-Dawley rat.

Choroid plexus cysts are rare lesions in the brain and are reported in humans and dogs. Herein, we report a choroid plexus cyst found in a 10-week-old female Sprague-Dawley rat. Histologically, a cyst measuring approximately 600 µm in diameter was found in the fourth ventricle of the brain. The cyst was lined with a single layer of flattened cells and was present in the connective tissue of the choroid plexus. Next to the cyst, a dilated tube was found with a similar morphology to the epithelium of the choroid plexus. Immunohistochemistry revealed that flattened cells lining the cyst were positive for cytokeratin and vimentin, and negative for GFAP and S-100, which is the same as in the normal choroid plexus, excluding vimentin. We diagnosed the present cyst as a spontaneously occurring choroid plexus cyst that was considered to be undergoing the epithelial-mesenchymal transition.

Lack of genotoxic mechanisms in early-stage furan-induced hepatocellular tumorigenesis in gpt delta rats.

Furan has been used as an intermediate in the chemical-manufacturing industry and has been shown to contaminate various foods. Although furan induces hepatocellular tumors in rodents, equivocal results from in vitro and in vivo mutagenicity tests have caused controversy regarding the involvement of genotoxic mechanisms in furan-induced carcinogenesis. In the present study, to elucidate the possible mechanisms underlying furan-induced hepatocarcinogenesis, a comprehensive medium-term analysis was conducted using gpt delta rats treated with furan at carcinogenic doses for 13 weeks. In the liver, the frequencies of gpt and Spi- mutants derived mainly from point and deletion mutations, respectively, were not changed, and there were no furan-specific gpt mutations in furan-treated rats. In contrast, the number and area of glutathione S-transferase placental form (GST-P)- positive foci were significantly increased in the high-dose group. Also, the ratio of PCNA-positive hepatocytes was significantly elevated in the same group, as supported by significant increases in cyclin d1 and cyclin e1 mRNA levels. Thus, it is highly probable that cell proliferation, but not genotoxic mechanisms, contribute to the development of GST-P foci in furan-treated rats. Based on the close relationship between GST-P and neoplastic hepatocytes, these data allowed us to hypothesize that cell proliferation following signal transduction other than the mitogen-activated protein kinase (MAPK)/ERK pathway may play a crucial role in early-stage furan-induced hepatocarcinogenesis. Copyright © 2016 John Wiley & Sons, Ltd.

Chemical structure-related mechanisms underlying in vivo genotoxicity induced by nitrofurantoin and its constituent moieties in gpt delta rats.

Nitrofurans are antimicrobial compounds containing a nitro group at the 5-position of the furan ring and an amine or hydrazide side chain derivative. One member of the nitrofurans, nitrofurantoin (NFT), is a renal carcinogen in male rats despite its still controversial genotoxicity. We investigated chemical structure-related modes of action of NFT, and reporter gene mutation assays for NFT and its constituent moieties were performed. NFT, 5-nitro-2-furaldehyde (NFA), or 1-aminohydantoin (AHD) was administered to male F344 gpt delta rats by gavage for 4 or 13 weeks at a carcinogenic or the maximum tolerated dose. NFT caused a significant increase in gpt mutant frequency (MF) at 13 weeks with G-base substitution mutations. An increase in gpt MF was also observed in the NFA-treated group at 13 weeks, but not in the AHD-treated group. 8-Hydroxydeoxyguanosine (8-OHdG) levels in the kidney DNA of NFT-treated rats were significantly increased after 4 weeks. NFT caused accumulation of hyaline droplets indicated by positive immunostaining and western blot analysis for α2u-globulin in the proximal tubules. An additional study, in which female gpt delta rats were given NFT at the same dose used for males, was performed to mitigate the effect of α2u-globulin. NFT exerted the same effects on female rat kidneys to the same extent as males in terms of gpt MF and 8-OHdG level. Thus, it is highly probable that the structure of the nitro furan plays a key role in NFT-induced genotoxicity and genotoxic mechanisms including oxidative DNA damage are involved in NFT-induced renal carcinogenesis. α2u-globulin-mediated nephropathy may be a prerequisite for NFT-induced renal carcinogenesis in male rats, and additionally NFT could be a latent carcinogen in female rats and other animal species.

Role of p53 in the progression from ochratoxin A-induced DNA damage to gene mutations in the kidneys of mice.

Carcinogenic doses of ochratoxin A (OTA) cause increases of mutant frequencies (MFs) of the red/gam gene (Spi(-)) in the kidneys of p53-deficient gpt delta mice, but not in p53-proficient mice. Here, we investigated the role of p53 in the progression from OTA-induced DNA damage to gene mutations. To this end, p53-proficient and -deficient mice were administered 5 mg/kg OTA for 3 days or 4 weeks by gavage. After 3 days of administration, comet assays were performed and there were no differences in the degrees of OTA-induced DNA damage between p53-proficient and -deficient mice. However, the frequencies of γ-H2AX-positive tubular epithelial cells in p53-deficient mice were significantly higher than those in p53-proficient mice, implying that p53 inhibited the progression from DNA damage to DNA double-strand breaks (DSBs). Evaluation of global gene expression and relevant mRNA/protein expression levels demonstrated that OTA increased the expression of Cdkn1a, which encodes the p21 protein, in p53-proficient mice, but not in p53-deficient mice. Moreover, in p53-deficient mice, mRNA levels of cell cycle progression and DSB repair (homologous recombination repair [HR])-related genes were significantly increased. Thus, G1/S arrest due to activation of the p53/p21 pathway may contribute to the prevention of DSBs in p53-proficient mice. In addition, single base deletions/insertions/substitutions were predominant, possibly due to HR. Overall, these results suggested that OTA induced DSBs at the carcinogenic target site in mice and that p53/p21-mediated cell cycle control prevented an increase in the formation of DSBs, leading to gene mutations.

Lack of nrf2 results in progression of proliferative lesions to neoplasms induced by long-term exposure to non-genotoxic hepatocarcinogens involving oxidative stress.

To explore the role of oxidative stress in chemical carcinogenesis driven by non-genotoxic mechanisms, nrf2-deficient (nrf2(-/-)) and nrf2-wild-type (nrf2(+/+)) mice were exposed to pentachlorophenol (PCP) at concentrations of 600 or 1200 ppm for 60 weeks, or piperonyl butoxide (PBO) at concentrations of 3000 or 6000 ppm in the diet for 52 weeks, respectively. Additional studies were performed to examine 8-hydroxydeoxyguanosine (8-OHdG) levels in liver DNA and hepatotoxicological parameters in serum following 8 weeks of exposure of each group to PBO at the same doses as in the long-term study. Exposure to 600 ppm PCP caused cholangiofibrosis (CF) only in nrf2(-/-) mice, while 1200 ppm PCP induced CF in both genotypes. Moreover, cholangiocarcinomas were found with significant incidence only in nrf2(-/-) mice treated with 1200 ppm PCP. Short-term exposure to 6000 ppm PBO caused significant elevation of 8-OHdG levels in both genotypes, while exposure to 3000 ppm caused a significant increase in 8-OHdG only in nrf2(-/-) mice. There were no inter-genotype changes in the incidences of regenerative hepatocellular hyperplasia (RHH) following long-term exposure to PBO. However, the incidence and multiplicity of hepatocellular adenomas, especially those observed in RHH, were much higher in nrf2-/- mice treated with 6000 ppm PBO than in nrf2+/+ mice treated with 6000 ppm PBO. Therefore, oxidative stress generated through PCP or PBO metabolism may promote the proliferation and progression of preneoplastic lesions to neoplasms.

Ochratoxin A induces DNA double-strand breaks and large deletion mutations in the carcinogenic target site of gpt delta rats.

Ochratoxin A (OTA) is a carcinogen targeting proximal tubules at the renal outer medulla (ROM) in rodents. We previously reported that OTA increased mutant frequencies of the red/gam gene (Spi(-)), primarily deletion mutations. In the present study, Spi(-) assays and mutation spectrum analyses in the Spi(-) mutants were performed using additional samples collected in our previous study. Spi(-) assay results were similar to those in our previous study, revealing large (>1kb) deletion mutations in the red/gam gene. To clarify the molecular progression from DNA damage to gene mutations, in vivo comet assays and analysis of DNA damage/repair-related mRNA and/or protein expression was performed using the ROM of gpt delta rats treated with OTA at 70, 210 or 630 µg/kg/day by gavage for 4 weeks. Western blotting and immunohistochemical staining demonstrated that OTA increased γ-H2AX expression specifically at the carcinogenic target site. In view of the results of comet assays, we suspected that OTA was capable of inducing double-strand breaks (DSBs) at the target sites. mRNA and/or protein expression levels of homologous recombination (HR) repair-related genes (Rad51, Rad18 and Brip1), but not nonhomologous end joining-related genes, were increased in response to OTA in a dose-dependent manner. Moreover, dramatic increases in the expression of genes involved in G2/M arrest (Chek1 and Wee1) and S/G2 phase (Ccna2 and Cdk1) were observed, suggesting that DSBs induced by OTA were repaired predominantly by HR repair, possibly due to OTA-specific cell cycle regulation, consequently producing large deletion mutations at the carcinogenic target site.

Molecular mechanisms underlying ochratoxin A-induced genotoxicity: global gene expression analysis suggests induction of DNA double-strand breaks and cell cycle progression.

Ochratoxin A (OTA) is a renal carcinogen primarily affecting the S3 segment of proximal tubules in rodents. In our previous study, we reported that OTA induces reporter gene mutations, primarily deletion mutations, in the renal outer medulla (OM), specifically in the S3 segment. In the present study, to identify genes involved in OTA-induced genotoxicity, we conducted a comparative analysis of global gene expression in the renal cortex (COR) and OM of kidneys from gpt delta rats administered OTA at a carcinogenic dose for 4 weeks. Genes associated with DNA damage and DNA damage repair, and cell cycle regulation were site-specifically changed in the OM. Interestingly, genes that were deregulated in the OM possessed molecular functions such as DNA double-strand break (DSB) repair (Rad18, Brip1, and Brcc3), cell cycle progression (Cyce1, Ccna2, and Ccnb1), G(2)/M arrest in response to DNA damage (Chek1 and Wee1), and p53-associated factors (Phlda3 and Ccng1). Significant increases in the mRNA levels of many of these genes were observed in the OM using real-time RT-PCR. However, genes related to oxidative stress exhibited no differences in either the number or function of altered genes in both the OM and COR. These results suggested that OTA induced DSB and cell cycle progression at the target site. These events other than oxidative stress could trigger genotoxicity leading to OTA-induced renal tumorigenicity.

Oxidative DNA damage and in vivo mutagenicity caused by reactive oxygen species generated in the livers of p53-proficient or -deficient gpt delta mice treated with non-genotoxic hepatocarcinogens.

Oxidative stress is thought to participate in chemical carcinogenesis and may trigger gene mutations. To accurately assess the carcinogenesis risk posed to humans by chemical exposure, it is important to understand the pathways by which reactive oxygen species (ROS) are generated and the effects of the resulting oxidative stress. In the present study, p53-proficient and -deficient gpt delta mice were given pentachlorophenol (PCP), phenobarbital (PhB) or piperonyl butoxide (PBO), which are classified as non-genotoxic hepatocarcinogens in rodents, at the respective carcinogenic doses for 13 weeks. Exposure to PCP or PBO, but not PhB, invoked significant increases in liver DNA 8-hydroxydeoxyguanosine (8-OHdG) levels. Treatment with PCP significantly increased mRNA levels of the gene encoding NAD(P):quinone oxidoreductase 1 (NQO1) in the liver, suggesting that redox cycling of the PCP metabolite tetrachlorohydroquinone gave rise to ROS. Exposure to PhB or PBO significantly elevated CYP 2B10 mRNA levels while NQO1 levels were also significantly increased in PBO-treated mice. Therefore, in addition to involvement of the CYP catalytic pathway in the ROS-generated system of PBO, catechol derivatives produced from the opening of the PBO functional group methylenedioxy ring probably resulted in ROS generation. However, PCP, PBO and PhB failed to increase gpt and red/gam gene mutations in the liver independently of p53. Overall, the action of oxidative stress by ROS derived from the metabolism of these carcinogens might be limited to cancer-promoting activity, which supports the previous classification of these carcinogens as non-genotoxic.

Effects of p53 knockout on ochratoxin A-induced genotoxicity in p53-deficient gpt delta mice.

Ochratoxin A (OTA) is a mycotoxin produced by fungal species and is carcinogenic targeting the S3 segment of the renal proximal tubules in rodents. We previously reported that exposure of gpt delta rats to OTA induced both mutations in the red/gam gene (Spi(-)), suggesting large deletion mutations, and fluctuations in genes transcribed by p53 in the kidneys, which were associated with DNA double-strand break (DSB) repair, particularly homologous recombination (HR) repair. In the present study, to investigate the effects of p53 knockout on OTA-induced mutagenicity, apoptosis, and karyomegaly in renal tubular cells, p53-proficient and p53-deficient gpt delta mice were given 1 and 5mg/kg of OTA for 4 weeks. Significant increases in Spi(-) mutant frequencies (MFs) were observed in the kidneys of p53-deficient gpt delta mice given 5 mg/kg of OTA, but not in the kidneys of p53-proficient gpt delta mice given the same dose. There were no changes in gpt MFs in both genotypes of mice treated with OTA. Western blotting analysis demonstrated that p53 protein levels in the kidneys of p53-proficient mice given OTA were significantly increased compared with the control. Incidences of apoptosis and karyomegaly in not only the outer stripe of outer medulla but also the cortex were significantly higher in p53-deficient at 5mg/kg than in p53-proficient gpt delta mice at same dose, which had no change in the cortex, the inner stripe of outer stripe, and the inner medulla. Given that p53 regulates HR repair in DSBs, these results suggest that OTA may promote large deletion mutations in the process of HR repair for DSBs. Additionally, the lower incidence of karyomegaly and apoptosis found in the p53-proficient gpt delta mice suggests that these phenomena may arise from OTA-induced DNA damage.

In vivo genotoxicity of methyleugenol in gpt delta transgenic rats following medium-term exposure.

Methyleugenol (MEG), which is commonly used as a fragrance and flavoring agent, has been shown to induce hepatocellular tumors in rodents. However, the role of genotoxicity as a possible mechanism of action is not fully understood even though the DNA-reactive metabolite of MEG has been identified. In this study, a gpt delta transgenic rat model was used to clarify whether genotoxic mechanisms are involved in MEG-induced hepatocarcinogenesis following medium-term exposure. F344 gpt delta rats were subjected to repeated oral administration of MEG at dosages of 0, 10, 30, or 100mg/kg (a carcinogenic dose) for 13 weeks. The relative weight of the liver of the male and female rats that were administered 100mg/kg MEG and the absolute weight of the liver of the male rats that were administered 100mg/kg MEG were significantly increased. In addition, the number and area of glutathione S-transferase placental form (GST-P) positive foci and proliferating cell nuclear antigen (PCNA) positive cell ratios in the hepatocytes were significantly increased in the male and female rats that were administered 100mg/kg MEG compared with the control animals. In the in vivo mutation assays, a significant increase in the gpt and Spi(-) mutant frequencies was observed in both sexes at the carcinogenic dose. These results suggest the possible participation of genotoxic mechanisms in MEG-induced hepatocarcinogenesis.

Possible involvement of sulfotransferase 1A1 in estragole-induced DNA modification and carcinogenesis in the livers of female mice.

Estragole (ES), a natural organic compound, is frequently used as a flavoring in food even though it is a hepatocarcinogen in mice. Although formation of ES-specific DNA adducts following conversion from ES to the nucleophilic metabolite by sulfotransferase 1A1 (SULT1A1) has been reported, the modes of action underlying ES-induced hepatocarcinogenesis remain uncertain because conventional genotoxicity tests for ES yield negative results. In the present study, taking notice of the fact that there is a sex difference in SULT1A1 activity in the mouse liver, we assessed the frequency of micronuclei in polychromatic erythrocytes and the mutant frequency (MF) of reporter genes in female gpt delta mice treated with ES at doses of 0 (corn oil), 37.5, 75, 150 or 300mg/kg body weight (bw) by gavage for 13 weeks. Results were compared with those obtained in males. Since one female was found dead at week one, the highest dose was reduced to 250mg/kg bw in females from week two. As reported previously in C57BL/6 mice, the mRNA levels of Sult1a1 in female gpt delta mice were significantly higher than those in the males. The levels of ES-specific DNA adducts in the females were higher than those in the males at all doses except the highest dose. In addition, MFs of the gpt gene were significantly increased from doses of 75mg/kg bw of females, but the increment was observed only at the highest dose in males. There were no changes in the micronucleus test among the groups. Thus, the overall data suggest that specific DNA modifications by the SULT1A1-mediated carbocation formation and the resultant genotoxicity are key events in the early stage of ES-induced hepatocarcinogenesis of mice.

In vivo genotoxicity of 1-methylnaphthalene from comprehensive toxicity studies with B6C3F1 gpt delta mice.

1-Methylnaphthalene (1-MN), a constituent of the polycyclic aromatic hydrocarbons (PAHs), is a lung carcinogen in mice. However, conventional genotoxicity tests such as the Ames test and sister chromatid exchange (SCE) test have yielded equivocal results. In the present study, the in vivo genotoxicity of 1-methylnaphthalene (1-MN) together with its toxicological profile was investigated in a 13-week repeated dose toxicity study of 1-MN using B6C3F1 gpt delta mice. In the serum biochemistry, significant increases in AST and ALP were observed in males of the 0.15% 1-MN group. From histopathological examination, the incidence of single cell necrosis in the liver was significantly increased in males of the 0.15% 1-MN group; however, no changes were observed in the lungs, the target organ of 1-MN. In an in vivo mutation assay, no changes in mutant frequencies of gpt and red/gam (Spi-) in lung DNA of 1-MN treated mice were observed at 13 weeks. In addition, there were no significant differences in the proliferating cell nuclear antigen (PCNA)-positive ratios in bronchiolar epithelial cells among the groups for either sex. These results suggest that 1-MN at a carcinogenic dose not induce overt toxicity for any organs and has no in vivo genotoxicity in the lungs.

Possible involvement of genotoxic mechanisms in estragole-induced hepatocarcinogenesis in rats.

Estragole (ES) is a natural organic compound used frequently as a flavoring food additive. Although it has been reported to be tumorigenic and induce DNA adducts in the mouse liver, there have been no reports regarding ES hepatocarcinogenicity in rats. In the current study, we therefore examined potent carcinogenicity, DNA adduct formation and in vivo genotoxicity of ES in the livers of wild and reporter gene-carrying F344 rats. Males were administered 600 mg/kg bw ES by gavage and sequentially sacrificed at weeks 4, 8 and 16 for GST-P and PCNA immunohistochemistry and measurement of ES-specific DNA adducts by LC-MS/MS in the livers. GST-P-positive foci increased with time in ES-treated rats from week 4, PCNA-labeling indices being similarly elevated at both weeks 4 and 8. ES-specific DNA adducts such as ES-3'-N(2)-dG, 3'-8-dG and 3'-N(6)-dA were consistently detected, particularly at week 4. In a second study, male F344 gpt delta rats were administered 0, 22, 66, 200 or 600 mg/kg bw ES for 4 weeks. Gpt mutant frequency in the liver was increased in a dose-dependent manner, with significance at 200 and 600 mg/kg bw in good correlation with PCNA-labeling indices. Mutation spectra analysis showed A:T to G:C transitions to be predominantly increased in line with the formation of ES-3'-N(6)-dA or 3'-8-dG. These results indicate that ES could be a possible genotoxic hepatocarcinogen in the rat, at least when given at high doses.

Site-specific in vivo mutagenicity in the kidney of gpt delta rats given a carcinogenic dose of ochratoxin A.

Ochratoxin A (OTA) can induce renal tumors that originate from the S3 segment of the proximal tubules in rodents, but the results of conventional mutagenicity tests have caused controversy regarding the role of genotoxic mechanisms in the carcinogenesis. Human exposure to OTA from various foods is unavoidable. Therefore, an understanding of OTA-induced renal carcinogenesis is necessary for accurate estimates of the human risk hazard. In the present study, a 13-week exposure of gpt delta rats to OTA at a carcinogenic dose induced karyomegaly and apoptosis at the outer stripe of the outer medulla (OM) of the kidney but failed to affect the reporter gene mutations in DNA extracted from whole kidneys. This site specificity resulting from the kinetics of specific transporters might be responsible for the negative outcome of in vivo mutagenicity. The kidney was then macroscopically divided, based on anatomical characteristics, into the cortex, the OM, and the inner medulla, each of which was histopathologically confirmed. Spi⁻ mutant frequencies (MFs) but not gpt MFs in the OM after a 4-week exposure to OTA were significantly higher than in controls despite the absence of cortical changes. There were also no changes in 8-hydroxydeoxyguanosine levels in kidney DNA. These results strongly suggest the involvement of a genotoxic mechanism, with the exception of oxidative DNA damage in OTA-induced renal carcinogenesis. In addition, the reporter gene mutation assay using DNA from target sites could be a more powerful tool to investigate in vivo genotoxicities.

Detection and quantification of specific DNA adducts by liquid chromatography-tandem mass spectrometry in the livers of rats given estragole at the carcinogenic dose.

Estragole (ES) is a natural constituent of several herbs and spices that acts as a carcinogen in the livers of rodents. Given that the proximal electrophilic form of ES with a reactive carbocation is generated by cytochrome P450 and a sulfotransferase metabolizing pathway, there is a possibility that the resultant covalent adducts with DNA bases may play a key role in carcinogenesis. The existence of ES-specific deoxyguanosine (dG) and deoxyadenosine (dA) adducts has already been reported with the precise chemical structures of the dG adducts being confirmed. In the present study, we examined ES-specific dA adduct formation using LC-ESI/MS after the reaction of dA with 1'-acetoxy-ES produced by a sulfotransferase metabolic pathway mimic. Although two peaks were observed in the LC-ESI/MS chromatogram, the identification of ES-3'-N(6)-dA as the measurable peak was determined by NMR analysis. To confirm ES-specific dG and dA adduct formation in vivo, an isotope dilution LC-ESI/MS/MS method applicable to in vivo samples for ES-3'-N(6)-dA together with the two major dG adducts, that is, ES-3'-C8-dG and ES-3'-N(2)-dG, was developed using selected ion recording. The limit of quantification was 0.2 fmol on column for ES-3'-C8-dG and ES-3'-N(2)-dG and 0.06 fmol on column for ES-3'-N(6)-dA, respectively. Using the developing analytical method, we attempted to measure adduct levels in the livers of rats treated with ES at a possible carcinogenic dose (600 mg/kg bw) for 4 weeks. ES-3'-C8-dG, ES-N(2)-dG, and ES-3'-N(6)-dA were detected at levels of 3.5 ± 0.4, 4.8 ± 0.8, and 20.5 ± 1.6/10(6) dG or dA in the livers of ES-treated rats. This quantitative data and newly developed technique for adduct observation in vivo might be helpful for ES hepatocarcinogenesis investigations.

Uterine Carcinosarcoma in a 2-year-old Female Wistar Hannover GALAS Rat.

Carcinosarcomas are rare tumors in humans as well as rats and most commonly occur in the uterus. Recently, we observed a case of incidental carcinosarcoma of the uterus in a female Wistar Hannover GALAS [BrlHan:WIST@ Jcl (GALAS)] rat at 2 years of age. Histopathologically, the tumor was characterized by an admixture of malignant epithelial and nonepithelial elements. The carcinomatous components represented a type of endometrial carcinoma, consisting of glandular and solid proliferation of large-sized tumor cells. Prominent mitoses and tumor cell invasion were observed. The sarcomatous components were characterized by multifocal proliferation of severe atypical cells with cartilage matrix and were diagnosed as chondrosarcoma. Transitions between carcinomatous and sarcomatous components were observed, and many tumor cells in the solid lesion showed immunohistochemical reactivity with both cytokeratin and vimentin. Based on these findings, this tumor was diagnosed as a uterine carcinosarcoma. This is the first report of uterine carcinosarcoma in Wistar Hannover GALAS [BrlHan:WIST@Jcl (GALAS)] rats.