Guillermo M. Zúñiga-González

Spontaneous micronuclei in peripheral blood erythrocytes from 54 animal species (mammals, reptiles and birds): part two.

The normal numbers of micronucleated erythrocytes (MNE) observed in peripheral blood samples differ among species. This depends on the effectiveness of the spleen (or the rest of the reticuloendothelial system) to withdraw them from circulation. In our previous report, we assessed the number of MNE in the peripheral blood of 35 mammalian species. Here we show the results observed in 54 species including mammals, reptiles and birds. We obtained 212 peripheral blood samples from different species. In 14 species, only one individual was studied. Slides were stained with acridine orange. The total number of MNE (normo and polychromatic) in 10,000 erythrocytes per animal are shown. The species that display the higher MNE were: ocelote, lynx, owl, gray squirrel, hedgehog, lion, orange fronted parakeet and common barn owl. For this reason, these species could be tested as monitors for genotoxic events. Another interesting observation was that in the gray squirrel, we found the highest values of MNE in the smaller (younger) animals when compared with the larger (older) of the same species.

Differences in the number of micronucleated erythrocytes among young and adult animals including humans. Spontaneous micronuclei in 43 species.

In our previous report we speculated about the possibility that some species had high levels of spontaneous micronucleated erythrocytes (MNE) just in a juvenile stage, this is, that the MNE diminish as the reticuloendothelial system matures. Here we show this effect in species including rat, rabbit, pig, dog, cat, gray squirrel, lion, giraffe, white-tailed deer, opossum and even human. The number of spontaneous MNE that we found in 43 species is shown, and the proportions of polychromatic and normochromatic. This is our third report on spontaneous MNE in different species. We obtained 189 peripheral blood samples of mammals, birds and reptiles. From 12 species we obtained only one sample, and 16 were reported previously, but now the size of the sample has been increased. The species with the highest spontaneous MNE were the Vietnamese potbelly pig (with the highest MNE number), Bengal tiger, capuchin monkey, puma, ferret, owl, hedgehog, squirrel monkey, pig and white-tailed deer. These species could be used as monitors for genotoxic events.

Urinary Glycosaminoglycan Excretion in Healthy Subjects and in Patients with Mucopolysaccharidoses

BACKGROUND The mucopolysaccharidoses (MPS) are a group of lysosomal storage disorders caused by deficiency of enzymes catalyzing the stepwise degradation of glycosaminoglycans (GAGs), and are transmitted in an autosomal recessive manner, except for Hunter syndrome. METHODS The levels of GAGs in 150 healthy subjects and 33 patients with MPS were determined, and results were expressed as milligrams of GAGs per grams of creatinine. RESULTS We found that this ratio decreased with age during the first 15 years of life, but had a constant low rate between the ages of 17-40 years in healthy individuals. A different tendency was present in patients with MPS, because levels of GAG excretion in this group were higher (by four standard deviations up) compared with healthy individuals. The electrophoretic patterns of urinary GAGs in healthy subjects showed that the higher levels detected in urine were chondroitin sulfate (4 and 6) and a smaller quantity of dermatan sulfate, but in each MPS type its characteristic pattern was identified. CONCLUSIONS This is a simple, reproducible method suitable for routine laboratory separation, identification, and quantity of urinary GAGs and for diagnosing MPS syndromes.

Induction of Micronucleated Erythrocytes in Mouse Peripheral Blood After Cutaneous Application of 5-Fluorouracil

BACKGROUND For topically applied drugs such as 5-fluorouracil (5-FU), dosage is not as precise as for other drug administration pathways. Consequently, quantity of drug delivered may differ among individuals and applications. 5-FU is used in treatment of different diseases and has been reported as a clastogenic compound by micronucleus assay. METHODS To determine whether 5-FU cream (5% 5-FU) absorbed through skin can produce genotoxic or cytotoxic effect in mouse bone marrow, induction of micronucleated erythrocytes (MNE) in mouse peripheral blood was examined after cutaneous application of 5-FU daily for 5 days. RESULTS 5-FU cream induced significant micronuclei at doses of 37.5 mg (total weight of cream)/2 cm(2) and 75.0 mg/2 cm(2), as well as cytotoxic effects at doses of 150.0 and 300.0 mg/2 cm(2). CONCLUSIONS Cutaneous application of 5-FU increased number of MNE in mouse peripheral blood. These data emphasize the importance of using correct dose when applying drugs topically.

Intron 4 VNTR (4a/b) Polymorphism of the Endothelial Nitric Oxide Synthase Gene Is Associated with Breast Cancer in Mexican Women

The endothelial nitric oxide synthase (eNOS) gene plays an important role in several biological functions. Polymorphisms of the eNOS gene have been associated with cancer. It has been suggested that the VNTR 4 a/b polymorphism may affect the expression of eNOS and contributes to tumor promotion in the mammary gland. We examined the role of the eNOS4 a/b polymorphism by comparing the genotypes of 281 healthy Mexican women with the genotypes of 429 Mexican women with breast cancer (BC). The observed genotype frequencies for control and BC patients were 0.6% and 0.7% for a/a (polymorphic); 87% and 77% for a/a (wild type); and 12% and 22% for a/b respectively. We found that the odds ratio (OR) was 1.9, with a 95% confidence interval (95%CI) of 1.29-2.95, P = 0.001 for genotypes a/a-a/b, b/c. The association was also evident when comparing the distribution of the a/a-a/b genotypes in patients with high levels of glutamate-oxaloacetate transaminase (SGOT) (OR, 1.93; 95% CI, 1.14-3.28; P = 0.015); undergoing menopause with high levels of SGOT (OR, 2.0; 95% CI, 1.1-3.84); and with high levels of glutamic-pyruvic transaminase (SGPT) (OR, 3.5; 95% CI, 1.56-8.22). The genotypes a/a-a/b are associated with BC susceptibility in the analyzed samples from the Mexican population.

Distribution of CYP1A1⁎2A polymorphism in adult patients with acute lymphoblastic leukemia in a Mexican population

The effects of the CYP1A1*2A genotype on susceptibility to leukemia have received particular attention in recent years because this enzyme plays a central role in the activation of carcinogens. Several polymorphisms at the CYP1A1 locus have been identified and their genotypes appear to exhibit population frequencies that depend on ethnicity. We evaluated the role of the CYP1A1*2A genotype in adults with acute lymphoblastic leukemia (ALL) by genotyping 210 patients and 228 healthy controls from the Mexican population. The frequency of the CC genotype was 8% (18/228) in the control group and 42% (88/210) in ALL patients; the frequency of the CT genotype was 39% (89/228) and 29.5% (62/210), respectively; and that of the TT genotype was 53% (121/228) and 28.5% (60/210), respectively. The odds ratio was 8.4 (95% CI, 4.7-15.5; P < 0.001). These data indicate that the CYP1A1*2A genotype contributes significantly to susceptibility to adult ALL in a sample of the Mexican population.

Increased number of micronuclei and nuclear anomalies in buccal mucosa cells from people exposed to alcohol-containing mouthwash

The aim of this study was to evaluate the effects of alcohol-containing mouthwash on the induction of micronuclei and nuclear anomalies in exfoliated buccal cells, including binucleated cells, cells with nuclear buds, and karyolitic, karyorrhectic, condensed chromatin, and pyknotic cells. Buccal mucosa cells were collected from 107 healthy participants who were divided into three groups: control subjects who did not use mouthwash (n = 33), subjects who were exposed for 30 days and two times rinsing with 30 seconds each time to alcohol-containing mouthwash (n = 38; 26% ethanol concentration); and subjects exposed to a non-alcohol-containing mouthwash (n = 36). A slide was used to collect cells from the oral mucosa from the inner lining of both cheeks. Samples were spread directly onto two separate, precleaned and precoded slides. Smears were air-dried, fixed, stained, and analyzed by microscopy for micronuclei and nuclear anomalies. Frequency of micronuclei, nuclear buds, and karyolitic, karyorrhectic, and condensed chromatin cells increased significantly (P < 0.05) in the alcohol-containing mouthwash group after mouthwash exposition, compared with both the control and the non-alcohol-containing mouthwash groups. Our results suggest that subjects exposed to alcohol-containing mouthwash exhibited an increase in frequency of micronuclei and nuclear anomalies in oral mucosal cells, which is directly related to DNA damage.

The association between the 844ins68 polymorphism in the CBS gene and breast cancer

Introduction The cystathionine beta synthase (CBS) gene plays an important role in homocysteine metabolism because it catalyzes the first step of the transsulfuration pathway, during which homocysteine is converted to cystathionine. Polymorphisms of CBS have been associated with cancer. Material and methods We examined the role of the 844ins68 polymorphism by comparing the genotypes of 371 healthy Mexican women with the genotypes of 323 Mexican women with breast cancer (BC). Results The observed genotype frequencies for controls and BC patients were 1% and 2% for Ins/Ins, 13% and 26% for W/Ins, and 86% and 72% for W/W, respectively. We found that the odds ratio (OR) was 2.2, with a 95% confidence interval (95% CI) of 1.5–3.3, p = 0.0001. The association was also evident when comparing the distribution of the W/Ins-Ins/Ins genotypes in patients in the following categories: 1) menopause and high γ-glutamyltransferase (GGT) levels (OR of 2.17, 95% CI: 1.17–4.26, p = 0.02), 2) chemotherapy response and high lactate dehydrogenase (LDH) levels (OR 2.2, 95% CI: 1.08–4.4, p = 0.027), 3) chemotherapy response and high GGT levels (OR 2.46, 95% CI: 1.2–4.8, p = 0.007), and 4) body mass index (BMI) and III–IV tumor stage (OR 3.2, 95% CI: 1.2–8.3, p = 0.013). Conclusions We conclude that the genotypes W/Ins-Ins/Ins of the 844ins68 polymorphism in the CBS gene contribute significantly to BC susceptibility in the analyzed sample from the Mexican population.

Evaluation of genotoxic activity of maleic hydrazide, ethyl methane sulfonate, and N-nitroso diethylamine in Tradescantia

OBJECTIVE To assess the genotoxic activity of N-nitroso diethylamine (NDEA), maleic hydrazide (MH), and ethyl methane sulfonate (EMS) using two systems: the comet assay on nuclei from Tradescantia, and the pink mutation test on Tradescantia staminal hairs (clone 4430). MATERIAL AND METHODS Tradescantia cups was obtained from Laboratorio de Citogenética y Mutagénesis del Centro de Ciencias de la Atmósfera de la Universidad Nacional Autónoma de México and treated with: N-nitroso diethylamine (NDEA) at 1, 5, 10 mM, maleic hydrazide (MH) at 1, 5, 10 mM and ethyl methane sulfonate (EMS) at 15, 30 and 45 mM; and used in both pink mutation assay and comet assay using cellular nuclei from Tradescantia staminal hairs. The observation of staminal hair was realized along eight days (6-14) after treatment), flowers produced day 14 after treatment were utilized done according to Underbrink. In previous reports on plants, were comet assay was used, breaking cellular wall and separating by centrifugation gradient are necessary. Here, nuclei from staminal hairs were obtained by squashing the cells (is not necessary to utilize to break special procedure cellular wall), collected using a nylon mesh of 80 Mm and next the comet assay was applied. Students T test was the statistical test used for analyzing the comet assay data. RESULTS Both assays showed a great sensitivity to the studied mutagens. A relationship between the dose-pink event and the dose-tail length was evident. Even though the Tradescantia mutation assay is a sensitive test with MH and EMS, low doses of NDEA were not able to induce a significant increase in the pink event frequencies; however, the comet assay was able to detect the mutagenic effect of NDEA at the same dose. Thus, it is clear that the comet assay is highly sensitive to the lowest dose of chemical mutagens. CONCLUSIONS The comet assay on nuclei from Tradescantia staminal hairs is a useful tool to monitor genotoxic agents; it is simple, highly sensitive, and faster than the pink mutation test.

Induction of micronuclei in the domestic cat (Felis domesticus) peripheral blood by colchicine and cytosine-arabinoside

One advantage of bioassays over other kinds of tests is the processing or metabolism of the compound by the organism. In a previous work, in which we reported the number of micronucleated erythrocytes (MNE) in the peripheral blood of 35 species, the cat was one of the species with the highest number of micronuclei (MN). Cats have a low level of circulating polychromatic erythrocytes (PCE), i.e. 0.05%, which is much lower than in the laboratory mouse, but higher than in species such as cows, donkeys, sheep, goats and horses. Thus, MN were scored in total blood erythrocytes. In the present work, we assess the cat as a test system for MN induction. Three doses of a colchicine-cytosine arabinoside mixture were administered to young cats during 4 days; then, the numbers of MNE in blood collected before the first injection and 48 and 96 h later were compared. The number of MNE increased with time, reaching the highest values in the samples taken 96 h after the administration of the micronucleogenic agents.