[Suitability of Culture Broth and Conditions for Escherichia coli Growth and Gas Production as a Test for Food Additives in EC Broth].

The growth and gas production test for Escherichia coli in the microbiological examination of food additives is stipulated in the ninth edition of Japan's Specifications and Standards for Food Additives (JSFA) and described as a part of the "Confirmation Test for Escherichia coli" in "Microbial Limit Tests" in the same manuscript. The growth and gas production test for E. coli indicated that the positive or negative of "gas production and/or turbidity" in EC broth should be confirmed after incubating at 45.5±0.2℃ for 24±2 h. If both gas production and turbidity are negative, the culture is additionally incubated up to 48±2 h to determine E. coli contamination. The internationally referenced Bacteriological Analytical Manual of the U.S. FDA had revised the incubation temperature in tests for coliforms and E. coli from 45.5±0.2℃ to 44.5±0.2℃ in 2017. Therefore, we conducted research in anticipation of this temperature change being reflected in the microbiological examination of the JSFA. We used seven EC broth products and six food additives across eight products that are available in Japan in order to compare the growth and gas production at temperatures of 45.5±0.2℃ and 44.5±0.2℃ of E. coli NBRC 3972, which is designated as the test strain in JSFA. Both with/without food additives, the number of EC broth products in which medium turbidity and gas production by the strain were positive in three out of three tubes at all test times was greater at 44.5±0.2℃ than at 45.5±0.2℃. These results suggest that the growth and gas production test for E. coli could be more appropriately conducted by incubation at 44.5±0.2℃ in the "Confirmation Test for Escherichia coli" for E. coli in the JSFA in comparison to 45.5±0.2℃. Furthermore, there were differences in the growth and gas production of E. coli NBRC 3972 depending on the EC broth product used. Therefore, the importance of "Media growth promotion test" and "Method suitability test" in the ninth edition of the JSFA should be emphasized.

Determination of the biological origin of enzyme preparations using SDS-PAGE and peptide mass fingerprinting.

Enzymes are mainly extracted from the culture broth of microorganisms. Various commercially available enzyme preparations (EPs) are derived from different microorganisms, and the source of the EP should be the same as that mentioned in the manufacture's information. The development of analytical methods that can determine the origin of the final products is important for ensuring that the EPs are nontoxic, especially when used as food additives. In this study, various EPs were subjected to SDS-PAGE, and the main protein bands were excised. After in-gel digestion, the generated peptides were analysed using MALDI-TOF MS, and protein identification was performed by searching the set of peptide masses against protein databases. In total, 36 EPs including amylase, ß-galactosidase, cellulase, hemicellulase and protease were analysed, and the information about the enzyme sources was obtained for 30 EPs. Among these, the biological sources determined for 25 EPs were consistent with the manufacturer's information; for the remaining five, enzymes produced by closely-related species were shown as matching proteins due to high sequence similarity. Six enzymes derived from four microorganisms could not be identified because their protein sequences were not registered in the database. As these databases are expanded, this approach of using SDS-PAGE and peptide mass fingerprinting (PMF) can determine the biological origin of enzymes rapidly and contribute to ensuring the safety of EPs.

Association between participation in hospital-led community activities and sense of security in continued community living among older adults in a rural district of Japan: A cross-sectional study.

For older adults to continue living in a community, they need to have a certain sense of security, especially in terms of the availability of healthcare in the community. The aim of this cross-sectional study was to explore important factors of the sense of security among older adults in their continued community living, with particular attention to hospital-led community activities. The participants comprised 252 randomly sampled older adults aged 65 years or older, living in a local community in western Japan, and ranging from being independent to physically and cognitively frail. Participants' sense of security in continued community living was assessed using a modified scale from past research on cancer care. Activities provided by local community organisations and hospitals were examined. The participants' mean age was 75.0 years, 144 (57.8%) were female and 32 (13.3%) were frail. Hospital-led groups (e.g. health lectures) and individual (e.g. health counselling) activities were used by 73 (30.5%) and 76 (31.9%) participants respectively. Among participants, 174 (73.4%) had participated in activities run by the local community, such as senior day celebrations or senior centre activities. A stronger sense of security was associated with participation in hospital-led individual activities (ß = 0.171, p = .036), being a member of a neighbourhood association (ß = 0.156, p = .020), frequency of contact with family members (ß = 0.145, p = .034) and lower depression (ß = -0.269, p < .001). Participation in community hospital-led individual activities may provide older adults opportunities to discuss their health-related concerns in a community setting, and thus might enhance their sense of security. In the aged society, the role of healthcare facilities may need to be expanded to facilitate outreach for older adults in the community to enhance their sense of security and actualise ageing in place.

Clinical Features of Patients with Active Eosinophilic Granulomatosis with Polyangiitis Successfully Treated with Mepolizumab.

BACKGROUND: In some patients with eosinophilic granulomatosis with polyangiitis (EGPA), remission cannot be induced, despite treatment with corticosteroids and immunosuppressants. We evaluated the clinical features of patients with EGPA in whom mepolizumab was effective. METHODS: There were 59 EGPA patients treated at Hiratsuka City Hospital, Japan, between April 2018 and September 2020, and 30 of them received mepolizumab. Twenty (66.7%) experienced a "marked effect" (the daily dose of corticosteroid or immunosuppressant could be decreased, or the interval between intravenous immunoglobulin (IVIG) treatments could be prolonged) and 10 (33.3%) experienced a "weak effect" (these measures were not achieved). Eosinophil numbers, serum IgG levels, daily doses of corticosteroids and immunosuppressants, and the interval between IVIG treatments at diagnosis and before and after mepolizumab initiation were determined. RESULTS: Eosinophil numbers at diagnosis were significantly higher in the marked-effect group than in the weak-effect group (p < 0.05) but not before mepolizumab initiation or at the last visit. Birmingham Vasculitis Activity Scores (BVASs) before mepolizumab initiation (p < 0.05) and at last visit (p < 0.01), and frequency of relapse before treatment initiation (p < 0.05) were significantly higher, and the serum IgG level before mepolizumab treatment was significantly lower in the weak-effect group than in the marked-effect group. The weak-effect group received higher doses of corticosteroids, even if the corticosteroid dose could be reduced for a while after mepolizumab initiation. CONCLUSION: High peripheral blood eosinophil numbers at EGPA diagnosis were suggestive of a positive clinical response to mepolizumab.

Medical Care-Related Decisions among Patients Diagnosed with Early Stage Malignant Brain Tumor: A Qualitative Study.

Medical care-related decision-making among patients with malignant brain tumors has not been sufficiently discussed. This study aimed to develop a framework for understanding patients' experiences in the decision-making process. Semi-structured interviews with 14 patients were analyzed using a grounded theory approach, focusing on their 48 decision-making points. Additionally, interviews with two family members and seven healthcare providers, and participant observations were used to gain contextual insight into patients' experiences. Patients faced decisions while they struggled in vulnerability under shock, fear, and anxiety while hoping. Under this context, they showed four decision-making patterns: (1) led by the situation, (2) controlled by others, (3) entrusted someone with the decision, and (4) myself as a decision-making agent. Across these patterns, the patients were generally satisfied with their decisions even when they did not actively participate in the process. Healthcare providers need to understand patients' contexts and their attitudes toward yielding decision-making to others.

Proenkephalin+ regulatory T cells expanded by ultraviolet B exposure maintain skin homeostasis with a healing function.

Regulatory T (Treg) cells, expressing CD25 (interleukin-2 receptor α chain) and Foxp3 transcription factor, maintain immunological self-tolerance and suppress various immune responses. Here we report a feature of skin Treg cells expanded by ultraviolet B (UVB) exposure. We found that skin Treg cells possessing a healing function are expanded by UVB exposure with the expression of an endogenous opioid precursor, proenkephalin (PENK). Upon UVB exposure, skin Treg cells were expanded with a unique TCR repertoire. Also, they highly expressed a distinctive set of genes enriched in "wound healing involved in inflammatory responses" and the "neuropeptide signaling pathway," as indicated by the high expression of Penk. We found that not only was PENK expression at the protein level detected in the UVB-expanded skin Treg (UVB-skin Treg) cells, but that a PENK-derived neuropeptide, methionine enkephalin (Met-ENK), from Treg cells promoted the outgrowth of epidermal keratinocytes in an ex vivo skin explant assay. Notably, UVB-skin Treg cells also promoted wound healing in an in vivo wound closure assay. In addition, UVB-skin Treg cells produced amphiregulin (AREG), which plays a key role in Treg-mediated tissue repair. Identification of a unique function of PENK+ UVB-skin Treg cells provides a mechanism for maintaining skin homeostasis.

A New Protocol for the Detection of Sterigmatocystin-producing Aspergillus Section Versicolores Using a High Discrimination Polymerase.

Aspergillus section Versicolores species, except Aspergillus sydowii, produce a carcinogenic mycotoxin sterigmatocystin (STC). Since these fungi are found in varied environmental milieu including indoor dust and food products, our aim was to develop a sensitive and convenient assay to detect STC producing fungal strains. We made use of a high discrimination DNA polymerase (HiDi DNA polymerase), for single nucleotide polymorphism (SNP)-based PCR amplification. Using specific primer pairs based on the SNPs between A. sydowii and other strains of Aspergillus section Versicolores, we succeeded in amplifying the genomic DNA all target strains except A. sydowii. These results confirm that the SNP-based PCR amplification technique, using a high discrimination DNA polymerase, was a reliable and robust screening method for target fungal strains.

Innate immune response reflects disease activity in eosinophilic granulomatosis with polyangiitis.

BACKGROUND: Eosinophilic granulomatosis with polyangiitis (EGPA) is a disease characterized by allergic granulomatosis, necrotizing vasculitis, and peripheral blood eosinophilia. Interleukin (IL)-33, thymic stromal lymphopoietin (TSLP), and type 2 innate lymphoid cells (ILC2) are involved in the innate and type 2 immune responses in EGPA. However, the relationships among these molecules and the mechanisms underlying the development of EGPA remain unknown. OBJECTIVE: We investigated the relationships among peripheral blood eosinophil count, serum IL-33 and TSLP concentration, and peripheral blood ILC2 count in patients with EGPA, chronic eosinophilic pneumonia (CEP), or bronchial asthma (BA). METHODS: We recruited 86 patients with EGPA in three groups (remission, relapse, and onset), 25 patients with CEP at active or inactive stages of disease, and 11 patients with BA. In patients with EGPA, CEP, or BA, serum IL-33, sST2, and TSLP concentrations were determined using ELISA and peripheral blood ILC2 counts (as Lin-1- CD127+ CRTH2+ cells) were determined using flow cytometry. RESULTS: Peripheral blood eosinophil count or ILC2 count, and serum sST2 or TSLP concentration were higher in patients with EGPA at onset than in those with EGPA at relapse or remission, or in those with BA or CEP. Serum IL-33 concentration was higher in patients with EGPA at relapse than in those with EGPA at onset or remission, or in those with BA or CEP. In a logistic regression model, EGPA disease activity was correlated with serum IL-33 concentration and peripheral blood ILC2 count, but not daily systemic and inhaled corticosteroid dose or immunosuppressant use. Eosinophil count was correlated with peripheral blood ILC2 count and serum TSLP concentration, but not serum IL-33 concentration. CONCLUSIONS: Increased peripheral blood ILC2 count and serum IL-33 concentration were associated with disease activity in EGPA. Increases in serum IL-33 concentration may indicate the presence of active vasculitis rather than peripheral or tissue eosinophilia.

The Experience of Persons With Hematological Malignancy When Communicating With Health Care Professionals.

This study aimed to elucidate the experiences of Japanese persons with hematological malignancy (PHMs) in communicating with health care professionals (HCPs), from diagnosis to the end of life, as recalled by their families. We interviewed 14 bereaved families and analyzed the data using the basic techniques of grounded theory. We found that PHMs lived to the fullest possible when they experienced ownership of their illness process despite their disease. The ownership was made possible by active communication from HCPs: first, acknowledging the PHM's way of life, including reaching out from the HCPs and appreciating sincerely PHMs' hopes and will; and second, paving the way ahead, including giving prospects and offering choices. The study underlines that rather than just providing information about the disease, HCPs need to actively ask about and show respect for the PHM's way of life. Only after achieving this can HCPs communicate possible future pathways with PHMs.

Characterization of Sarcocystis fayeri's actin-depolymerizing factor as a toxin that causes diarrhea.

Raw horsemeat has the potential to induce food poisoning which often presents with diarrheal symptoms. A sample of horsemeat was found to be infected with Sarcocystis fayeri, and a 15-kDa protein isolated from the cysts of S. fayeri was found to clearly show its diarrhea-inducing activity. A nested polymerase chain reaction was used to clone the cDNA of the 15-kDa protein. The deduced amino acid sequence showed homology to actin-depolymerizing factor (ADF). A recombinant 15-kDa protein depolymerized prepolymerized actins in a test tube. The 15-kDa protein possessed conserved amino acid sequences of ADF of Toxoplasma gondii and Eimeria tenella. These characteristics indicate that the 15-kDa protein of S. fayeri belongs to the ADF/cofilin protein family. The recombinant 15-kDa protein evoked fluid accumulation in the looped ileum, resulting in diarrhea, but it did not kill the cultured fibroblast cells, macrophages or intestinal mucosal cells. In addition, the culture supernatant of the macrophages treated with the recombinant 15-kDa protein killed the fibroblast L929 cells. This fact indicates that ADF of S. fayeri induced cytotoxic substances, such as tumor necrosis factor-α, according to the published reports. Although further experiments are needed now to elucidate the enterotoxic mechanism of S. fayeri's ADF, our findings may offer new insight into research on parasites and parasite-instigated food poisoning.

Relationship between patient group participation and self-care agency among patients with a history of cardiac surgery: A cross-sectional study.

BACKGROUND: Little is known regarding the influence of participation in patient groups on self-care in patients with a cardiac surgery history. OBJECTIVES: To investigate the relationship between patient group participation and self-care among patients with a cardiac surgery history. METHODS: Participants were 956 patients with cardiac surgery history from a patient group. Information on self-care agency, patient group participation, and health status was collected through a self-administered questionnaire. RESULTS: There were 566 valid responses. Participants were mostly male (76.4%), and the mean age was 70.6 years. A high social support level from a patient group was associated with each subscale of the self-care agency as follows: self-care operations (odds ratio [OR] 1.08, 95% confidence interval [CI] 1.04-1.12), adjusting one's condition (OR 1.04, 95% CI 1.01-1.07), and attention to self-care (OR 1.05, 95% CI 1.02-1.07). CONCLUSIONS: Patient group participation may promote self-care performance in patients with a cardiac surgery history.

Postmortem diagnosis of massive gastrointestinal bleeding in a patient with aberrant right subclavian artery-esophageal fistula.

Case: Aberrant right subclavian artery-esophageal fistula is a rare, but fatal, complication. A 55-year-old febrile man with a nasogastric feeding tube developed sudden massive hematemesis and shock. Outcome: Upper endoscopy revealed an intragastric hematoma with no active bleeding observed except for oozing from an esophageal tear. Enhanced computed tomography scan detected aberrant right subclavian artery but was unable to determine the bleeding source. Repeat endoscopy carried out on day 2 confirmed hemostasis and the disappearance of the intragastric hematoma. However, the patient suddenly developed recurrent massive hematemesis with refractory shock on day 4 and died. Postmortem computed tomography revealed endoscopic clips in contiguity with aberrant right subclavian artery; a final diagnosis of aberrant right subclavian artery-esophageal fistula was made. Conclusion: Our case demonstrates aberrant right subclavian artery-esophageal fistula may present with transient spontaneous hematemesis in a state of shock, possibly related to fever of unknown origin, and is challenging to diagnose by repeated endoscopy once hematemesis develops.

A toxin isolated from Sarcocystis fayeri in raw horsemeat may be responsible for food poisoning.

Food poisoning has been reported after the consumption of raw horsemeat in Japan. Diarrhea with a short incubation period is a common symptom in such cases of food poisoning. Cysts found in horsemeat ingested by patients have been identified as Sarcocystis fayeri based on morphological and genetic evaluation and findings from experimental feeding of cysts to dogs, which resulted in the excretion of sporocysts. The extracts of the horsemeat containing the cysts produced a positive enterotoxic response in the rabbit ileal loop test. Intravenous injection of a 15-kDa protein isolated from the cysts induced diarrhea and lethal toxicity in rabbits, and the protein produced enterotoxicity in the ileal loop test as did the extracts of the horsemeat containing the cysts. The partial amino acid sequence of the 15-kDa protein was homologous to the actin-depolymerizing factor of Toxoplasma gondii and Eimeria tenella. These findings indicate that the 15-kDa protein of S. fayeri is a toxin that causes food poisoning after consumption of parasitized horsemeat.

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.

Cell cycle progression, but not genotoxic activity, mainly contributes to citrinin-induced renal carcinogenesis.

Citrinin (CTN) is a food-contaminating mycotoxin that efficiently induces renal tumors in rats. However, the modes of carcinogenic action are still unknown, preventing assessment of the risks of CTN in humans. In the present study, the proliferative effects of CTN and its causal factors were investigated in the kidneys of gpt delta rats. In addition, three in vivo genotoxicity assays (reporter gene mutation using gpt delta rats and comet and micronucleus assays using F344 rats) were performed to clarify whether CTN was genotoxic in vivo. CTN was administrated at 20 and 40mg/kg/day, the higher dose being the maximal tolerated dose and a nearly carcinogenic dose. In the kidney cortex of gpt delta rats, significant increases in the labeling indices of proliferating cell nuclear antigen (PCNA)-positive cells were observed at all doses of CTN. Increases in the mRNA expression levels of Ccna2, Ccnb1, Ccne1, and its transcription factor E2f1 were also detected, suggesting induction of cell cycle progression at all tested doses of CTN. However, histopathological changes were found only in rats treated with the higher dose of CTN, which was consistent with increases in the mRNA expression levels of mitogenic factors associated with tissue damage/regeneration, such as Hgf and Lcn2, at the same dose. Thus, the proliferative effects of CTN may result not only from compensatory reactions, but also from direct mitogenic action. Western blot analysis showed that ERK phosphorylation was increased at all doses, implying that cell cycle progression may be mediated by activation of the ERK pathway. On the other hand, in vivo genotoxicity analyses were negative, implying that CTN did not have the potential for inducing DNA damage, gene mutations, or chromosomal aberrations. The overall data clearly demonstrated the molecular events underlying CTN-induced cell cycle progression, which could be helpful to understand CTN-induced renal carcinogenesis.

[Control of toxicity of Sarcocystis fayeri in horsemeat by freezing treatment and prevention of food poisoning caused by raw consumption of horsemeat].

More than 27 outbreaks per year of food poisoning caused by consuming horse meat were reported in Kumamoto Prefecture (including Kumamoto City) from January 2009 to September 2011. It was found that the causative agent of the outbreaks was a protein with a molecular weight of 15 kDa that had originated from bradyzoites of Sarcocystis fayeri parasitizing the horse meat. Rabit ileal loop tests showed that pepsin treatment of homogenates of frozen horse meat containing the cysts of S. fayeri induced loss of toxicity, presumably by digestion of the proteinous causative agent(s). Slices of horse meat containing the cysts were frozen at below -20°C for various periods. The cysts were collected after thawing the slices, then treated in an artificial stomach juice containing pepsin. The bradyzoites of the cysts kept at -20°C for 48 hr or more completely disappeared. Simultaneously, the 15 kDa protein also disappeared in the frozen cysts. After notifying the public and recommending freezing treatment of horse meat, no subsequent cases of food poisoning were reported. This indicates that freezing of horse meat is effective to prevent the occurrence of food poisoning caused by consuming raw horse meat containing S. fayeri.

Nontuberculous Mycobacterium Infections in Rheumatoid Arthritis Patients: The Serodiagnosis of Pulmonary Disease due to Mycobacterium avium Complex with an Enzyme Immunoassay Kit Detecting Glycopeptidolipid Core Antigen (Capilia MAC Antibody ELISA)®.

Nontuberculous mycobacteria (NTM) are ubiquitous environmental organisms that can cause various diseases, including pulmonary disease (PD). In patients with rheumatoid arthritis (RA), numerous pulmonary manifestations, including bronchiectasis, may develop into Mycobacterium avium-complex (MAC)-PD, which can be lethal in patients who are being treated with a tumor necrosis factor-alpha blocker. However, the bronchiectasis associated with NTM-PD is difficult to distinguish from that associated with RA by radiological imaging alone. In addition, the diagnosis of NTM-PD is often hampered by the ease of NTM contamination. For the serological diagnosis of MAC-PD, the enzyme immunoassay (EIA) kit, Capilia MAC Antibody ELISA®, determines the levels of serum IgA antibody to the glycopeptidolipid core of MAC. Here we describe the efficacy of this EIA kit for diagnosing MAC-PD, and we review the characteristics of NTM and the association between RA patients and NTM infections.

[Health behavior for prevention of knee pain among young-old persons living in a rural area: focus on presence of knee pain and sex differences].

OBJECTIVES: To determine the prevalence of knee pain, and implementation status of health behavior for knee pain among young-old persons living in a rural area in Japan by sex, and to study related factors. METHODS: An anonymous self-administered questionnaire covering demographic variables, lifestyle such as smoking, drinking, farm work, snow removal, 'ochanomi' (tea break with friends), hospital visits, knee pain, JKOM (Japanese knee osteoarthritis measure) and health behavior was distributed to 2,758 persons aged 65 to 74 years living in Minamiaizu town, a rural and snowy town of Fukushima Prefecture in November, 2008. RESULTS: Valid responses were obtained from 1,415 (response rate: 51.3%). The prevalence of knee pain was 35.1%, and twice as many women as men had pain in their knees. People with knee pain had a higher body mass index, higher risk of motor deterioration, lower frequency of going out, and more hospital visits than people without knee pain. Health behavior was emphasized by 657 persons (46.3%), and the rate was higher in people with knee pain. As to companions and information source for health behaviors, 'ochanomi' friends were popular for women and family members for men. Walking was more common and exercise and diet were less common in men than in women. Among the women with knee pain, the implementation rate of health behavior was higher in non-smokers, farm workers, and 'ochanomi' participants than in others. Among men without knee pain, the implementation rate was higher in non-smokers and in people with high scores on the JKOM subscale of "pain or stiffness" and "health status". Among women without knee pain, more people living alone and going out once or more a week focused on health behavior more than the other people. CONCLUSION: The prevalence of knee pain in this study was similar to that in a previous study on elderly living in a mountain area. Type, information source, companion and related factors of health behavior differed by sex and presence of knee pain; therefore, approaches for encouraging health behavior should be suited to the target population's characteristics. Many people obtain information from non-professionals, so health care workers should provide details about adequate methods for health behavior in a careful manner.

Cellular distribution of cell cycle-related molecules in the renal tubules of rats treated with renal carcinogens for 28 days: relationship between cell cycle aberration and carcinogenesis.

Some renal carcinogens can induce karyomegaly, which reflects aberrant cell division in the renal tubules, from the early stages of exposure. To clarify the cell cycle-related changes during the early stages of renal carcinogenesis, we performed immunohistochemical analysis of tubular cells in male F344 rats treated with carcinogenic doses of representative renal carcinogens for 28 days. For this purpose, the karyomegaly-inducing carcinogens ochratoxin A (OTA), ferric nitrilotriacetic acid, and monuron, and the non-karyomegaly-inducing carcinogens tris(2-chloroethyl) phosphate and potassium bromate were examined. For comparison, a karyomegaly-inducing non-carcinogen, p-nitrobenzoic acid, and a non-carcinogenic non-karyomegaly-inducing renal toxicant, acetaminophen, were also examined. The outer stripe of the outer medulla (OSOM) and the cortex + OSOM were subjected to morphometric analysis of immunoreactive proximal tubular cells. Renal carcinogens, irrespective of their karyomegaly-inducing potential, increased proximal tubular cell proliferation accompanied by an increase in topoisomerase IIα-immunoreactive cells, suggesting a reflection of cell proliferation. Karyomegaly-inducing carcinogens increased nuclear Cdc2-, γH2AX-, and phosphorylated Chk2-immunoreactive cells in both areas, the former two acting in response to DNA damage and the latter one suggestive of sustained G2. OTA, an OSOM-targeting carcinogen, could easily be distinguished from untreated controls and non-carcinogens by evaluation of molecules responding to DNA damage and G2/M transition in the OSOM. Thus, all renal carcinogens examined facilitated proximal tubular proliferation by repeated short-term treatment. Among these, karyomegaly-inducing carcinogens may cause DNA damage and G2 arrest in the target tubular cells.

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.