[ACNES syndrome, exploring the abdominal wall as source of abdominal pain]. / Síndrome de ACNES, explorando la pared abdominal como noxa del dolor abdominal.

Abdominal wall pain, specifically ACNES syndrome (Anterior Cutaneous Nerve Entrapment Syn drome), is part of the differential diagnosis of chronic abdominal pain. This syndrome is frequently overlooked and therefore underdiagnosed. OBJECTIVES: To describe the clinical and evolutionary cha racteristics of patients diagnosed with ACNES and to draw attention to this pathology. PATIENTS AND METHOD: A retrospective descriptive study was carried out in a reference center, between October 2016 and July 2021, in patients under 17 years of age, diagnosed with ACNES, who met at least two of four of the following findings: Carnett's sign, Pinch test, dysesthesia at the point of maximum pain, improvement after infiltration of local anesthetic, having ruled out visceral or functional abdo minal pathology. Epidemiological variables, symptoms, physical examination, complementary tests, treatment, and evolution data were collected. Descriptive statistics were used. RESULTS: 20 patients diagnosed with ACNES, 75% women, median age 12.85 years. The abdominal examination revea led Carnett's sign in 95%, Pinch test sign in 65%, and dysesthesia in 90% of patients. 65% reported pseudovisceral symptoms. 7 patients were overweight or obese. The most frequent location (50%) was the right iliac fossa, at T10-T11 level. One patient reported spontaneous improvement; 7 impro ved with oral analgesia; 9 patients were referred to the pain unit, of which 5 attended, and improved with anesthetic infiltration with bupivacaine-triamcinolone. The remaining 4 were lost to follow-up. CONCLUSION: ACNES should be considered in patients with chronic pain. A combination of typical findings in medical history and physical examination allows its diagnosis, therefore, avoiding unne cessary complementary tests. A step-up treatment strategy should be applied, beginning with oral analgesia, followed by anesthetic infiltration, and, finally, anterior neurectomy.

Valoración subjetiva de los padres en el manejo de las bronquiolitis / Subjective assessment of parents on the management of bronchiolitis

Introducción: Numerosos estudios concluyen que no hay diferencias significativas entre los distintos aerosoles utilizados en el tratamiento de las bronquiolitis. Sin embargo, en protocolos recientes, la adrenalina ha demostrado mayor eficacia que el placebo y los beta-2 agonistas a corto plazo, con una mejoría en los síntomas en los primeros 60 minutos. Objetivos: Demostrar que el uso de adrenalina nebulizada en los pacientes ingresados por bronquiolitis produce una mejoría subjetiva percibida por los cuidadores (en calidad del sueño, ingesta y estado general) e interfiere en los días de ingreso, respecto al uso de suero salino fisiológico (SSF). Pacientes y métodos: Estudio experimental, prospectivo, aleatorizado y simple ciego, en el que se incluyeron lactantes menores de 12 meses ingresados en nuestro hospital entre el 15 de octubre de 2015 y el 31 de marzo de 2016. Resultados: La muestra final fue de 58 niños, un 62% varones. La mediana de edad al ingreso fue de 2 meses (rango intercuartílico: 3), el 62% recibió adrenalina y el 38% SSF. No se hallaron diferencias en el número de días de oxigenoterapia ni en el de días de ingreso entre ambos grupos. Respecto a la apreciación de los padres sobre la ingesta, el sueño y el estado general, no encontramos diferencias estadísticamente significativas entre ambos aerosoles. Conclusiones: El uso de adrenalina no produce una mejoría subjetiva percibida por los cuidadores frente al uso de SS

Introduction: Several studies have concluded that there are no significant differences between the different aerosols used in the treatment of bronchiolitis. However, in recent protocols epinephrine has shown more short-term efficiency than the placebo and beta2-agonists, with an improvement of symptoms within the first 60 minutes. Objectives: To prove that the use of nebulized epinephrine in patients admitted with bronchiolitis leads to a subjective improvement as perceived by caregivers (regarding quality of sleep, food intake and general state of health) and that it affects the days of hospitalization, compared with the use of physiological saline solution (PSS). Patients and methods: Experimental, prospective, randomized, single-blind study. It includes breastfed babies <12 months old who were admitted in our hospital from 15th October 2015 to 31st March 2016. Results: 58 patients, 62% male in total. The median age at admission was 2 months (interquartile range 3). 62% received epinephrine and 38% were given PSS. No differences were found regarding the days of oxygen therapy or the days of admission between both groups. With regard to the parents' assessment of food intake, sleeping and general state of health, we did not find statistically significant differences between different aerosols. Conclusions: The use of epinephrine does not lead to a subjective improvement perceived by the caregivers compared with the use of PSS

Carcinogenic activity of pentabrominated diphenyl ether mixture (DE-71) in rats and mice.

Pentabrominated diphenyl ether (PBDE) flame retardants have been phased out in Europe and in the United States, but these lipid soluble chemicals persist in the environment and are found human and animal tissues. PBDEs have limited genotoxic activity. However, in a 2-year cancer study of a PBDE mixture (DE-71) (0, 3, 15, or 50 mg/kg (rats); 0, 3, 30, or 100 mg/kg (mice)) there were treatment-related liver tumors in male and female Wistar Han rats [Crl:WI(Han) after in utero/postnatal/adult exposure, and in male and female B6C3F1 mice, after adult exposure. In addition, there was evidence for a treatment-related carcinogenic effect in the thyroid and pituitary gland tumor in male rats, and in the uterus (stromal polyps/stromal sarcomas) in female rats. The treatment-related liver tumors in female rats were unrelated to the AhR genotype status, and occurred in animals with wild, mutant, or heterozygous Ah receptor. The liver tumors in rats and mice had treatment-related Hras and Ctnnb mutations, respectively. The PBDE carcinogenic activity could be related to oxidative damage, disruption of hormone homeostasis, and molecular and epigenetic changes in target tissue. Further work is needed to compare the PBDE toxic effects in rodents and humans.

Long noncoding RNA lincRNA-p21 is the major mediator of UVB-induced and p53-dependent apoptosis in keratinocytes.

LincRNA-p21 is a long noncoding RNA and a transcriptional target of p53 and HIF-1α. LincRNA-p21 regulates gene expression in cis and trans, mRNA translation, protein stability, the Warburg effect, and p53-dependent apoptosis and cell cycle arrest in doxorubicin-treated mouse embryo fibroblasts. p53 plays a key role in the response of skin keratinocytes to UVB-induced DNA damage by inducing cell cycle arrest and apoptosis. In skin cancer development, UVB-induced mutation of p53 allows keratinocytes upon successive UVB exposures to evade apoptosis and cell cycle arrest. We hypothesized that lincRNA-p21 has a key functional role in UVB-induced apoptosis and/or cell cycle arrest in keratinocytes and loss of lincRNA-p21 function results in the evasion of apoptosis and/or cell cycle arrest. We observed that lincRNA-p21 transcripts are highly inducible by UVB in mouse and human keratinocytes in culture and in mouse skin in vivo. LincRNA-p21 is regulated at the transcriptional level in response to UVB, and the UVB induction of lincRNA-p21 in keratinocytes and in vivo in mouse epidermis is primarily through a p53-dependent pathway. Knockdown of lincRNA-p21 blocked UVB-induced apoptosis in mouse and human keratinocytes, and lincRNA-p21 was responsible for the majority of UVB-induced and p53-mediated apoptosis in keratinocytes. Knockdown of lincRNA-p21 had no effect on cell proliferation in untreated or UVB-treated keratinocytes. An early event in skin cancer is the mutation of a single p53 allele. We observed that a mutant p53(+/R172H) allele expressed in mouse epidermis (K5Cre(+/tg);LSLp53(+/R172H)) showed a significant dominant-negative inhibitory effect on UVB-induced lincRNA-p21 transcription and apoptosis in epidermis. We conclude lincRNA-p21 is highly inducible by UVB and has a key role in triggering UVB-induced apoptotic death. We propose that the mutation of a single p53 allele provides a pro-oncogenic function early in skin cancer development through a dominant inhibitory effect on UVB-induced lincRNA-p21 expression and the subsequent evasion of UVB-induced apoptosis.

[Recognition of facial expression of emotions in Parkinson's disease: a theoretical review]. / Reconocimiento de expresiones faciales de emociones en la enfermedad de Parkinson: una revision teorica.

INTRODUCTION: Emotional facial expression is a basic guide during social interaction and, therefore, alterations in their expression or recognition are important limitations for communication. AIM: To examine facial expression recognition abilities and their possible impairment in Parkinson's disease. DEVELOPMENT: First, we review the studies on this topic which have not found entirely similar results. Second, we analyze the factors that may explain these discrepancies and, in particular, as third objective, we consider the relationship between emotional recognition problems and cognitive impairment associated with the disease. Finally, we propose alternatives strategies for the development of studies that could clarify the state of these abilities in Parkinson's disease. CONCLUSIONS: Most studies suggest deficits in facial expression recognition, especially in those with negative emotional content. However, it is possible that these alterations are related to those that also appear in the course of the disease in other perceptual and executive processes. To advance in this issue, we consider necessary to design emotional recognition studies implicating differentially the executive or visuospatial processes, and/or contrasting cognitive abilities with facial expressions and non emotional stimuli. The precision of the status of these abilities, as well as increase our knowledge of the functional consequences of the characteristic brain damage in the disease, may indicate if we should pay special attention in their rehabilitation inside the programs implemented.

Lesiones apocrinas de la mama / Apocrine lesions of the breast

El cambio apocrino del epitelio mamario es una alteraciónfrecuente habitualmente conocida como metaplasia apocrina. Aunque comúnmente se observa en el epitelio de revestimiento de quistes mamarios, existen otras lesiones, histológicamente más complejas, desde las hiperplasias de diverso grado, la adenosis esclerosante, al carcinoma in situ o invasor, también con citología apocrina. Su particular morfología se acompaña, además, de un perfil de marcadores inmunohistoquímicos distinto al de las lesiones ductales comunes similares: se caracterizan por la expresión de GCDFP, pero, además por la negatividad para receptores de estrógenos, progesterona y bcl-2, y positividad para receptores de andrógenos. El significado biológico de las lesiones apocrinas benignas, en cuanto a riesgo de carcinoma posterior, es controvertido, al igual que su posible carácter preneoplásico

Apocrine change of breast epithelium is a frequent lesion usually known as apocrine metaplasia. It is commonly observed on the lining epithelium of breast cysts, but there are also another histologycally more complex lesions, from hyperplasias or sclerosing adenosis to in situ or infiltrating carcinoma, with apocrine cytology. Besides its special morphology, apocrine metaplasia shows a distinctive immunohistochemical profile, different from similar usual ductal lesions: positivity for GCDFP and androgens receptors and negativity for oestrogen and progesterone receptors and for bcl-2. The risk of subsequent carcinoma in patients with benign apocrine lesions and its possible precancerous condition are controversial subjects

Absence of acrylamide-induced genotoxicity in CYP2E1-null mice: evidence consistent with a glycidamide-mediated effect.

Acrylamide, an animal carcinogen and germ cell mutagen present at low (ppm) levels in heated carbohydrate-containing foodstuffs, is oxidized by cytochrome P4502E1 (CYP2E1) to the epoxide glycidamide, which is believed to be responsible for the mutagenic and carcinogenic activity of acrylamide. We recently reported a comparison of the effects of acrylamide on the genetic integrity of germ cells of male wild-type and CYP2E1-null mice [B.I. Ghanayem, K.L. Witt, L. El-Hadri, U. Hoffler, G.E. Kissling, M.D. Shelby, J.B. Bishop, Comparison of germ-cell mutagenicity in male CYP2E1-null and wild-type mice treated with acrylamide: evidence supporting a glycidamide-mediated effect, Biol. Reprod. 72 (2005) 157-163]. In those experiments, dose-related increases in dominant lethal mutations were detected in uterine contents of female mice mated to acrylamide-treated wild-type males but not CYP2E1-null males, clearly implicating CYP2E1-mediated formation of glycidamide in the induction of genetic damage in male germ cells. We hypothesized that acrylamide-induced somatic cell damage is also caused by glycidamide. Therefore, to examine this hypothesis, female wild-type and CYP2E1-null mice were administered acrylamide (0, 25, 50mg/kg) by intraperitoneal injection once daily for 5 consecutive days. Twenty-four hours after the final treatment, blood and tissue samples were collected. Erythrocyte micronucleus frequencies were determined using flow cytometry and DNA damage was assessed in leukocytes, liver, and lung using the alkaline (pH>13) single cell gel electrophoresis (Comet) assay. Results were consistent with the earlier observations in male germ cells: significant dose-related increases in micronucleated erythrocytes and DNA damage in somatic cells were induced in acrylamide-treated wild-type but not in the CYP2E1-null mice. These results support the hypothesis that genetic damage in somatic and germ cells of mice-treated with acrylamide is dependent upon metabolism of the parent compound by CYP2E1. This dependency on metabolism has implications for the assessment of human risks resulting from occupational or dietary exposure to acrylamide. CYP2E1 polymorphisms and variability in CYP2E1 activity associated with, for example, diabetes, obesity, starvation, and alcohol consumption, may result in altered metabolic efficiencies leading to differential susceptibilities to acrylamide toxicities in humans.

Transgenic tumor models for carcinogen identification: the heterozygous Trp53-deficient and RasH2 mouse lines.

Genetically altered mouse models (GAMM) for human cancers have been critical to the investigation and characterization of oncogene and tumor suppressor gene expression and function and the associated cancer phenotype. Similarly, several of the mouse models with defined genetic alterations have shown promise for identification of potential human carcinogens and investigation of mechanisms of carcinogen-gene interactions and tumorigenesis. In particular, both the B6.129N5-Trp53 mouse, heterozygous for a p53 null allele, and the CB6F1-RasH2 mouse, hemizygous for the human H-ras transgene, have been extensively investigated. Using 26-week exposure protocols at or approaching the maximum tolerated dose, the summary results to date indicate the potential for GAMM to identify and, possibly, classify chemicals of potential risk to humans using short-term carcinogenicity experiments. This IWGT session focused on: (1) the development of recommendations for genetic/molecular characterization required in animals, tissues, and tumors before and after treatment for identification of presumptive human carcinogens based on the current state of knowledge, (2) identification of data gaps in our current state of knowledge, and (3) development of recommendations for research strategies for further development of our knowledge base of these particular models. By optimization of protocols and identification of significant outcomes and responses to chemical exposure in appropriate short-term mechanism-based genetically altered rodent models, strategies for prevention and intervention may be developed and employed to the benefit of public health.

[Paratesticular solitary fibrous tumor]. / Tumor fibroso solitario paratesticular.

OBJECTIVE: To describe an additional case of paratesticular solitary fibrous tumor. METHODS/RESULTS: A 67-year-old man presented a paratesticular mass lasting for one year. Histological examination showed a well-circumscribed lesion comprised of spindle cells proliferation without atypia, arranged in a fascicular pattern, intimately intertwining with thick collagen fibers. Tumor cells were strongly positive for vimentine and CD-34. Diagnostic criteria, clinical features and treatment of this condition are discussed. CONCLUSION: Solitary fibrous tumors are spindle cell neoplasm originally described in the pleura, but may occur in many different sites. Intrascrotal solitary fibrous tumors are uncommon and few cases have been reported.

Is p53 haploinsufficient for tumor suppression? Implications for the p53+/- mouse model in carcinogenicity testing.

The p53 tumor suppressor gene has been shown to be critical in preventing cancer in humans and mice. We have generated and extensively characterized p53-deficient mice lacking one (p53+/-) or both (p53-/-) p53 alleles. The p53-deficient mice are much more susceptible to an array of different tumor types than their wild-type (p53+/+) littermates. The enhanced tumor susceptibility of the p53+/- mice has made them one of several transgenic mouse models that are being considered as substitutes for standard 2-year rodent carcinogenicity assays. In order to fully exploit this model, it will be important to understand some of the basic biological and molecular mechanisms that underlie its enhanced tumor susceptibility. With this in mind, we have explored the fate of the remaining wild-type p53 allele in spontaneously arising p53+/- tumors and have shown that over half of these tumors retain an intact, functional wild-type p53 allele. This suggests that p53 is haploinsufficient for tumor suppression and that mere reduction in p53 dosage is sufficient to promote cancer formation. To support the idea that p53 is indeed a haploinsufficient tumor suppressor, we show here that normal p53+/- cells exhibit reduced parameters of growth control and stress response compared to their p53+/- counterparts. We hypothesize that the reduced p53 dosage in the p53+/- cells provides an environment more conducive to the development of further oncogenic lesions and the initiation of a tumor. Finally, we have assessed p53 loss of heterozygosity (LOH) in carcinogen-induced p53+/- tumors and have found that some agents induce tumors that almost invariably exhibit p53 LOH, whereas other agents induce tumors that often retain the wild-type p53 allele. Our preliminary data suggest that LOH is dependent on both the mechanism of genotoxicity of the agent utilized and the tissue type targeted.

Mutational spectrum of 1,3-butadiene and metabolites 1,2-epoxybutene and 1,2,3,4-diepoxybutane to assess mutagenic mechanisms.

1,3-Butadiene (BD) is a multisite carcinogen and is mutagenic in multiple tissues of B6C3F1 mice. BD is bioactivated to at least three directly mutagenic metabolites: 1,2-epoxybutene (EB), 1,2-epoxy-3,4-butanediol (EBD), and 1,2,3,4-diepoxybutane (DEB). However, the contribution of these individual metabolites to the carcinogenicity and in vivo mutatidnal spectrum of BD is uncertain. To assess the role of two BD metabolites EB and DEB in the in vivo mutagenicity of the parent compound BD, we examined the in vitro mutational spectra of EB and DEB in human and rodent cells. We also examined the in vivo mutagenicity and mutational spectrum of inhaled EB in the lung. In the bone marrow and spleen of B6C3F1 laci transgenic mice, BD-induced an increased frequency of the identical class of point mutations at A:T base pairs: AT-->GC transitions and AT-->TA transversions. BD exposure also induced an increased frequency of GC-->AT transitions in the spleen that was not observed in bone marrow, demonstrating tissue-specific differences in mutation spectrum. Exposure of Rat2 laci transgenic cells and human TK6 lymphoblasts to EB-induced an increased frequency of AT-->TA transversions. DEB exposure induced an increased frequency of AT-->TA transversions and partial deletions at hprt in human cells. In Rat laci transgenic cells, DEB was not mutagenic at laci but induced an increased frequency of micronuclei. In contrast to inhaled BD, inhaled DEB and EB were not mutagenic in the bone marrow or spleen. However, EB was mutagenic in the lungs. In the lung of mice, EB-induced specific increases in GC-->AT transitions, AT-->TA transversions, and deletion events. AT-->TA transversions are the most consistent mutation observed across biological systems following in vivo exposure to BD or in vitro exposures to EB and DEB. Although, BD exposure in mice induces chromosomal alterations and single base substitutions, the specific BD metabolite that induces the genetic events leading to tumors is uncertain. At present, it appears that only DEB can effectively induce this range of mutagenic events at levels of this metabolite that occur in the blood of mice exposed to BD. Detailed investigations to identify relevant biomarkers of BD exposure and response, particularly DNA adducts or lesions, that can be biologically linked to the range of genotoxic events known to occur in mice exposed to BD are needed.

Induction and time-dependent accumulation of micronuclei in peripheral blood of transgenic p53+/- mice, Tg.AC (v-Ha-ras) and parental wild-type (C57BL/6 and FVB/N) mice exposed to benzene by inhalation.

In this study, we determined the induction and time-dependent accumulation of micronuclei in the peripheral blood of transgenic C57BL/6 p53+/- mice (p53+/- mice), FVB/N Tg.AC v-Ha-ras mice (Tg.AC mice) and their isogenic parental strains, FVB/N and C57BL/6 following inhalation exposure to benzene. Our objective was to determine the impact of p53 heterozygosity in p53+/- mice and the v-Ha-ras transgene in Tg.AC mice on micronuclei induction following exposure to inhaled benzene. A flow cytometric technique that distinguishes micronucleated red blood cells (MN-RBC) from micronucleated reticulocytes (MN-RET) was used. Mice were exposed to 0, 100 or 200 p.p.m. benzene using three different exposure regimens that resulted in an equal weekly cumulative exposure (3000 p.p.m.x hours) to benezene: 100 p.p.m. for 6 h/day, 5 days/week, Monday to Friday (M-F); 100 p.p.m. for 10 h/day, 3 days/week, Monday, Wednesday, Friday (MWF); and 200 p.p.m. for 5 h/day, 3 days/week MWF. Significant elevations of MN-RBC and MN-RET were observed from 1 week exposure in all of the benzene-exposed groups that increased in a time-dependent manner for up to 13 weeks exposure. Fewer MN-RBC and MN-RET were induced in the 200 p.p.m. benzene exposure group than in mice exposed to 100 p.p.m. The reduction in the frequency of MN-RBC in the 200 p.p.m.x5 h benzene exposure group is probably due to metabolic saturation resulting in a lower bone marrow dose (concentration x time) than in the 100 p.p.m. exposure groups. No differences were observed in the frequency of MN-RBC or MN-RET in Tg.AC compared with the FVB/N isogenic controls. At certain time points the frequency of micronuclei was less in the heterozygous p53+/- mice than determined in the wild-type C57BL/6 isogenic parental strain. These results indicate that the heterozygous state in p53+/- mice, but not the v-Ha-ras transgene in Tg.AC mice can influence the induction of micronuclei by benzene.

Lung-specific mutagenicity and mutational spectrum in B6C3F1 lacI transgenic mice following inhalation exposure to 1,2-epoxybutene.

1,3-Butadiene (BD) is carcinogenic and mutagenic in B6C3F1 mice. BD inhalation induces an increased frequency of specific base substitution mutations in the bone marrow and spleen of B6C3F1 lacI transgenic mice. BD is bioactivated to at least three mutagenic metabolites: 1,2-epoxybutene (EB), 1,2-epoxy-3,4-butanediol (EBD), and 1,2,3,4-diepoxybutane (DEB), however, the contribution of these individual metabolites to the in vivo mutational spectrum of BD is uncertain. In the present study, lacI transgenic mice were exposed by inhalation (6h per day, 5 days per week for 2 weeks) to 0 or 29.9ppm of the BD metabolite, EB to assess its contribution to the in vivo mutational spectrum of BD. No increase in lacI mutant frequency was observed in the bone marrow or spleen of EB-exposed mice. The lack of mutagenicity in the bone marrow or spleen likely relate to insufficient levels of EB reaching these tissues. The lacI mutant frequency was increased 2.7-fold in the lungs of EB-exposed mice (mean+/-S.D., 9.9+/-3.0x10(-5)) compared to air control mice (3.6+/-0.7x10(-5)). DNA sequence analysis of 65 and 66 mutants from the lungs of air control and EB-exposed mice, respectively, revealed an increase in the frequency of two categories of base substitution mutation and deletions. Like mice exposed to BD, EB-exposed mice had an increased frequency of A:T-->T:A transversions. However, in contrast to the BD mutational spectra, G:C-->A:T transitions at 5'-CpG-3' sequences, occurred with increased frequency in the EB-exposed mice. The increased frequency of deletions as well as the induction of two tandem mutations and a tandem deletion in the lungs of EB-exposed mice are also inconsistent with previous mutational spectra from BD-exposed mice or EB-exposed cells in culture. We hypothesize that the direct in vivo mutagenicity and further in situ metabolism of EB in the lungs of EB-exposed mice played a prominent role in the generation of the current mutational spectrum.

Use of genetically modified mouse models for evaluation of carcinogenic risk: considerations for the laboratory animal scientist.

There has been increasing interest in the use of selected genetically modified (GM) mouse models for the testing of chemicals to determine their carcinogenic potential. GM mouse models are believed to be useful tools that offer mechanistically relevant insights for understanding and predicting the human response to chemical exposure. They have been proposed as alternatives to the traditional 2-year mouse oncogenicity bioassay. In this overview we will review the GM mouse models that have been proposed as bioassay alternatives and present some of the key laboratory animal science challenges that need to be considered when using these unique animals.

1,3-butadiene: cancer, mutations, and adducts. Part II: Roles of two metabolites of 1,3-butadiene in mediating its in vivo genotoxicity.

1,3-Butadiene (BD) is carcinogenic in mice and rats, with mice being more susceptible than rats to its carcinogenic effects. 1,3-Butadiene is mutagenic in the bone marrow and spleen cells of B6C3F1 lacI transgenic mice. The goal of this research was to assess the roles of two BD metabolites, 1,2-epoxy-3-butene (BDO) and 1,2,3,4-diepoxybutane (BDO2), in the mutagenicity and mutational spectrum of the parent compound BD by determining the mutagenicity and mutational spectra of BDO and BDO2 in human and rodent cells in vitro and in vivo. In human TK6 lymphoblastoid cells (TK6 cells), BDO exposure increased the frequency of G.C-->A.T transitions and A.T-->T.A transversions (Fisher exact test; p < 0.05). The most striking difference in the type of base-substitution mutations between BDO-exposed and BDO-unexposed TK6 cells was the 19-fold increase in A.T-->T.A transversions. 1,2,3,4-Diepoxybutane increased the frequency of A.T-->T.A transversions (Fisher exact test; p < 0.05) and the frequency of deletions in exposed TK6 cells compared with unexposed controls. Exposure of Rat2 lacI transgenic fibroblasts (Rat2 cells) to BDO increased the frequency of three types of base-substitution mutations: G.C-->A.T transitions, G.C-->T.A transversions, and A.T-->T.A transversions. Exposure of Rat2 cells to BDO2-induced dose-dependent increases in micronuclei at exposure levels that apparently did not induce mutagenicity at the lacI transgene. The lack of detectable mutagenicity at the lacI transgene in Rat2 cells exposed to BDO2 probably reflects the poor recovery of large deletions by this lambda phage-based mutagenicity assay. Inhalation exposure of B6C3F1 lacI transgenic mice (lacI mice) and F344 lacI transgenic rats (lacI rats) to BDO (29.9 parts per million [ppm]; 6 hours/day; 5 days/week for 2 weeks) did not increase the lacI mutant frequency (MF) in bone marrow or spleen cells of mice and rats, but in the cells of mouse lung (a tumor target organ for BD), significant mutagenicity was observed. An increased lacI MF was also observed in the bone marrow cells of rats exposed to BDO. Inhalation exposure of lacI mice and lacI rats to BDO2 (3.8 ppm; 6 hours/day; 5 days/week for 2 weeks) did not increase the lacI MF in bone marrow or spleen cells of mice or in the spleen cells of rats. An increased lacI MF was observed in the bone marrow cells of rats exposed to BDO2. In the present study, BDO specifically induced G.C-->A.T and A.T-->T.A transversions in vitro at both the endogenous hypoxanthine phosphoribosyltransferase (hprt) gene and the lacI transgene in Rat2 cells. It also induced an increased frequency of G.C-->T.A transversions in Rat2 cells. These types of mutations also occur at an increased frequency in mice exposed to the parent compound, BD. This finding demonstrates the induction of consistent mutational types across biological systems by BDO and indicates that BDO, but not BDO2, probably has a role in mediating the mutations recovered at the lacI transgene in animals exposed to the parent compound, BD. Therefore, it is apparent that in mice exposed to BD at carcinogenic levels, BDO and BDO2 act in concert to mediate the range of genotoxic responses. These data demonstrate that certain DNA adducts (guanine or adenine) may be useful biomarkers for BD genetic effects. However, other DNA lesions that can account for BDO2-induced deletions and chromosomal alterations also need to be considered as biomarkers for BD-induced genotoxicity.

Inhibition of cytochrome P450 2E1 decreases, but does not eliminate, genotoxicity mediated by 1,3-butadiene.

1,3-Butadiene (BD), a rodent carcinogen, is metabolized to mutagenic and DNA-reactive epoxides. In vitro data suggest that this oxidation is mediated by cytochrome P450 2E1 (CYP2E1). In this study, we tested the hypothesis that oxidation of BD by CYP2E1 is required for genotoxicity to occur. Inhalation exposures were conducted with B6C3F1 mice using a closed-chamber technique, and the maximum rate of butadiene oxidation was estimated. The total amount of butadiene metabolized was then correlated with the frequency of micronuclei (MN). Three treatment groups were used: (1) mice with no pretreatment; (2) mice pretreated with 1,2-trans-dichloroethylene (DCE), a specific CYP2E1 inhibitor; and (3) mice pretreated with 1-aminobenzotriazole (ABT), an irreversible inhibitor of cytochromes P450. Mice in all 3 groups were exposed to an initial BD concentration of 1100 ppm, and the decline in concentration of BD in the inhalation chamber with time, due to uptake and metabolism of BD, was monitored using gas chromatography. A physiologically based pharmacokinetic model was used to analyze the gas uptake data, estimate V(max) for BD oxidation, and compute the total amount of BD metabolized. Model simulations of the gas uptake data predicted the maximum rate of BD oxidation would be reduced by 60% and 100% for the DCE- and ABT-pretreated groups, respectively. Bone marrow was harvested 24 h after the onset of the inhalation exposure and analyzed for frequency of micronuclei in polychromatic erythrocytes (MN-PCE). The frequency of MN-PCE per 1000 PCE in mice exposed to BD was 28.2 +/- 3.1, 19.8 +/- 2.5, and 12.3 +/- 1.9, for the mice with no pretreatment, DCE-pretreated mice and ABT-pretreated mice, respectively. Although inhibition of CYP2E1 decreased BD-mediated genotoxicity, it did not completely eliminate genotoxic effects. These data suggest that other P450 isoforms may contribute significantly to the metabolic activation of BD and resultant genotoxicity.

Loss of p53 in benzene-induced thymic lymphomas in p53+/- mice: evidence of chromosomal recombination.

The purpose of this study was to examine the role of chromosomal recombination in mediating p53 loss in benzene-induced thymic lymphomas in C57BL/6-Trp53 haploinsufficient (N5) mice (p53+/- mice). We characterized loss of heterozygosity (LOH) on chromosome 11 using seven microsatellite markers in 27 benzene-induced and 6 spontaneous thymic lymphomas. Eleven patterns of LOH were found between the induced and spontaneous tumors, with only one pattern being in common between the tumor groups. Nearly 90% (24 of 27) of benzene-induced tumors exhibited loss of the functional p53 allele locus, and 83% (20 of 24) of these tumors retained two copies of the disrupted p53 allele. The results indicate that benzene induces a high frequency of LOH on chromosome 11 in p53+/- mice, likely mediated by aberrant chromosomal recombination.

Use of transgenic animals for carcinogenicity testing: considerations and implications for risk assessment.

Advances in genetic engineering have created opportunities for improved understanding of the molecular basis of carcinogenesis. Through selective introduction, activation, and inactivation of specific genes, investigators can produce mice of unique genotypes and phenotypes that afford insights into the events and mechanisms responsible for tumor formation. It has been suggested that such animals might be used for routine testing of chemicals to determine their carcinogenic potential because the animals may be mechanistically relevant for understanding and predicting the human response to exposure to the chemical being tested. Before transgenic and knockout mice can be used as an adjunct or alternative to the conventional 2-year rodent bioassay, information related to the animal line to be used, study design, and data analysis and interpretation must be carefully considered. Here, we identify and review such information relative to Tg.AC and rasH2 transgenic mice and p53+/- and XPA-/- knockout mice, all of which have been proposed for use in chemical carcinogenicity testing. In addition, the implications of findings of tumors in transgenic and knockout animals when exposed to chemicals is discussed in the context of human health risk assessment.

[Synchronous prostatic carcinosarcoma: report of 2 cases and review of the literature]. / Carcinosarcoma prostático sincrónico: presentación de dos casos y revisión de la literatura.

OBJECTIVE: Carcinosarcoma of the prostate is a biphasic tumor containing adenocarcinoma and recognisable sarcomatous components. It is a rare neoplasm with less than 40 reported cases. We describe two additional examples showing carcinosarcoma in the initial pathologic material (synchronous presentation). METHODS AND RESULTS: The patients were 71 and 78 year-old, respectively. The primary prostatic tumour in case one was composed of adenocarcinoma admixed with a neoplastic mesenchymal component that displayed foci of chondrosarcoma, rhabdomyosarcoma and angiosarcoma. The adenocarcinoma in the second case was admixed with spindle cell sarcoma and chondrosarcoma. Both patients died of disease after surgery, 3 and 9 months respectively. CONCLUSION: Synchronous carcinosarcoma of the prostate is a highly malignant neoplasm that may need an aggressive therapy.

Carcinosarcoma prostático sincrónico: presentación de dos casos y revisión de la literatura / Synchronous carcinosarcoma of the prostate: report of two cases and review of the literature

OBJETIVO: El carcinosarcoma prostático es un tumor bifásico que contiene adenocarcinoma y componentes sarcomatosos reconocibles. Es una neoplasia muy poco frecuente, de la que se han comunicado menos de 40 casos. Describimos dos ejemplos adicionales que muestran carcinosarcoma en el primer material anatomopatológico (presentación sincrónica). MÉTODOS Y RESULTADOS: Los pacientes tenían edades de 71 y 78 años. El tumor prostático primario en el Caso 1 estaba constituido por adenocarcinoma mezclado con un componente mesenqui-mal que mostraba focos de condrosarcoma, rabdomiosarcoma y angiosarcoma. El adenocarcinoma en el Caso 2 estaba mezclado con sarcoma fusocelular y condrosarcoma. Ambos pacientes murieron a causa de la enfermedad, tras cirugía, a los 3 y 9 meses respectivamente. CONCLUSIÓN: El carcinosarcoma prostático sincrónico es una neoplasia altamente maligna que puede precisar una terapia agresiva (AU)