Helena Groot de Restrepo

Bio: Helena Groot de Restrepo is an academic researcher from University of Los Andes. The author has contributed to research in topics: Population & Micronucleus test. The author has an hindex of 7, co-authored 19 publications receiving 253 citations.

Citotoxicidad y genotoxicidad en células humanas expuestas in vitro a glifosato

Abstract: Introduccion. El glifosato es un herbicida de amplio espectro, no selectivo, utilizado para eliminar malezas indeseables en ambientes agricolas y forestales. La accion herbicida corresponde a la inhibicion de la biosintesis de aminoacidos aromaticos en las plantas. Al no ser este mecanismo compartido por los seres humanos es considerado como de bajo riesgo para la salud de los mismos. Sin embargo, investigaciones recientes indican que puede alterar otros procesos celulares en animales lo que puede presentar un factor de riesgo a nivel ambiental y de salud en las zonas donde se emplea este herbicida. Objetivo. El objetivo del presente estudio fue evaluar la citotoxicidad y la genotoxicidad del glifosato en celulas humanas normales (GM38) y en celulas humanas de fibrosarcoma (HT1080). Materiales y metodos. La citotoxicidad aguda y cronica se determino al exponer las celulas en cultivo a diferentes concentraciones de glifosato, y se analizo la viabilidad celular con cristal violeta y colorante de exclusion azul de tripano, respectivamente. La genotoxicidad se determino por medio del ensayo del cometa y los datos se analizaron usando la prueba de Dunnet. Resultados. En la citotoxicidad cronica las celulas GM38 y las HT1080 presentaron un efecto dependiente de la dosis despues del tratamiento con glifosato en concentraciones de 5,2 a 8,5 mM y 0,9 a 3,0 mM, respectivamente. En la citotoxicidad aguda, las celulas GM38 y las HT1080 expuestas a un rango de concentraciones de 4,0 a 7,0 mM, 4,5 a 5,75 mM y 4,0 a 7,0 mM, respectivamente, presentaron una viabilidad mayor al 80%. Se evidencio dano en el ADN despues del tratamiento con glifosato en concentraciones de 4,0 a 6,5 mM para las celulas GM38 y de 4,75 a 5,75 mM para las celulas HT1080. Conclusiones. Se sugiere que el mecanismo de accion del glifosato no se limita unicamente a las plantas sino que puede alterar la estructura del ADN en otros tipos de celulas como son las de los mamiferos.

DNA damage and repair in cells of lead exposed people.

Abstract: Background One of the main sources of occupational exposure to lead in Colombia is in workers of battery industries and lead smelters. Genotoxic studies in human populations exposed to this metal have had conflicting results; this type of study has not been reported in Colombia. Methods Genotoxic effects of lead were studied in blood cell samples from workers of electric battery factories exposed to lead compounds. Single strand breaks and interference with DNA repair processes after an in vitro exposure of x-rays (300 cGy) were analyzed using the Comet Assay. The battery workers (n = 43) and 13 people not occupationally exposed to lead compounds who were selected as a control group, were classified into four categories according to their blood lead level. Results A significant difference was observed in DNA damage before the x-rays exposure (basal) between the lowest and highest categories of lead (mean DNA migration 55.6 μ and 85.9 μ, respectively). Additionally, a significant difference in DNA migration was also found immediately after irradiation between the lowest and highest lead categories (mean DNA migration. 199.8 μ and 317.8 μ respectively). The DNA migrations at different times after irradiation did not show a significant difference among the different lead levels. Conclusions We concluded that although the single strand breaks following irradiation were not affected by blood lead concentration, the metal seems to sensitize the cells to damage induced by other genotoxicants.

Susceptibilidad genética y riesgo de cáncer gástrico en una población del Cauca

Abstract: Gastric cancer (GC) is the main cause of mortality by cancer in Colombia. Glutathione S-transferase (GST) enzymes are involved in the detoxification of many environmental carcinogens. The homozygous deletions of glutathione S-transferase M1 (GSTM1-0) and glutathione S-transferase T1 (GSTT1-0) have been associated with several types of cancer. The risk to develop GC has been associated with environmental factors and Helicobacter pylori infection. The tumor necrosis factor (TNF-alpha) and its levels are increased in patients infected with H. pylori. A G/ A transition in the position -308 of the promoter of the TNF-alpha has been related in several studies to an increased expression of the gene and is associated with susceptibility to GC. The association of these polymorphisms with GC and the interaction with other risk factors (life style) were investigated. Blood samples were obtained from 46 GC patients and 96 controls. The logistic regression model was used to obtain the odds ratio (OR) and their 95% confidence intervals. These statistics established the association between the enzymatic polymorphisms and GC and between other independent factors and GC. The frequency of the TNF-alpha polymorphism in people infected with H. pylori was 18% in the GC population and 7% in the control group. This transition was not significantly associated with H. pylori infection and GC. The frequencies of the deletion polymorphisms for patients and controls were as follows: GSTM1 65.2% and 37.5%; GSTT1 17.4% and 14.6%. These results suggested that the GSTM1 deletion polymorphism was associated with an increased risk of gastric cancer (OR of 5.5; 95%CI, 1.7-17.2). Furthermore, other risk factors such as H. pylori infection (OR 5.58, CI 1.8-17.2), smoking (OR 6.70, CI 2.2-20.3) and alcohol intake (OR 3.27, CI 1.1-9.4) were associated with GC.

A revertant of the major founder Native American haplogroup C common in populations from northern South America.

Abstract: We examined the mtDNA RFLP diversity of 17 Native American populations from Colombia. Five of the populations studied were found to have variable frequencies of a mtDNA type lacking the characteristic changes of haplogroups A-D. Sequencing of mtDNA HVS-I and II showed that this "null" RFLP type carries all the substitutions characteristic of Native American founder lineage C. A back mutation has therefore recreated the + 13,259 HincII/-13,262 AluI restriction sites that tipify RFLP haplogroup C. This revertant C lineage is further characterized by three changes in HVS-II sequence: C/T transitions at positions 115 and 152, and the deletion of an A residue at position 116. This lineage is observed at high frequency mostly in populations from Greenberg's Equatorial-Tucano linguistic family. Genetic structure analyses are consistent with the reversion mutation occurring at an early stage during the tribalization process.

Inter-laboratory consistency and variability in the buccal micronucleus cytome assay depends on biomarker scored and laboratory experience: results from the HUMNxl international inter-laboratory scoring exercise

Abstract: The buccal micronucleus cytome (BMNcyt) assay in uncultured exfoliated epithelial cells from oral mucosa is widely applied in biomonitoring human exposures to genotoxic agents and is also proposed as a suitable test for prescreening and follow-up of precancerous oral lesions. The main limitation of the assay is the large variability observed in the baseline values of micronuclei (MNi) and other nuclear anomalies mainly related to different scoring criteria. The aim of this international collaborative study, involving laboratories with different level of experience, was to evaluate the inter- and intra-laboratory variations in the BMNcyt parameters, using recently implemented guidelines, in scoring cells from the same pooled samples obtained from healthy subjects (control group) and from cancer patients undergoing radiotherapy (treated group). The results indicate that all laboratories correctly discriminated samples from the two groups by a significant increase of micronucleus (MN) and nuclear bud (NBUD) frequencies and differentiated binucleated (BN) cells, associated with the exposure to ionizing radiation. The experience of the laboratories was shown to play an important role in the identification of the different cell types and nuclear anomalies. MN frequency in differentiated mononucleated (MONO) and BN cells showed the greatest consistency among the laboratories and low variability was also detected in the frequencies of MONO and BN cells. A larger variability was observed in classifying the different cell types, indicating the subjectivity in the interpretation of some of the scoring criteria while reproducibility of the results between scoring sessions was very good. An inter-laboratory calibration exercise is strongly recommended before starting studies with BMNcyt assay involving multiple research centers.

Brain tumor epidemiology: consensus from the Brain Tumor Epidemiology Consortium.

Abstract: Epidemiologists in the Brain Tumor Epidemiology Consortium (BTEC) have prioritized areas for further research. Although many risk factors have been examined over the past several decades, there are few consistent findings, possibly because of small sample sizes in individual studies and differences between studies in patients, tumor types, and methods of classification. Individual studies generally have lacked samples of sufficient size to examine interactions. A major priority based on available evidence and technologies includes expanding research in genetics and molecular epidemiology of brain tumors. BTEC has taken an active role in promoting understudied groups, such as pediatric brain tumors; the etiology of rare glioma subtypes, such as oligodendroglioma; and meningioma, which, although it is not uncommon, has only recently been registered systematically in the United States. There also is a pressing need for more researchers, especially junior investigators, to study brain tumor epidemiology. However, relatively poor funding for brain tumor research has made it difficult to encourage careers in this area. In this report, BTEC epidemiologists reviewed the group's consensus on the current state of scientific findings, and they present a consensus on research priorities to identify which important areas the science should move to address.

Detection of cytogenetic and DNA damage in peripheral erythrocytes of goldfish (Carassius auratus) exposed to a glyphosate formulation using the micronucleus test and the comet assay

Abstract: Glyphosate is a widely used broad-spectrum weed control agent In the present study, an in vivo study on the genotoxic effects of a technical herbicide (Roundup) containing isopropylamine salt of glyphosate was carried out on freshwater goldfish Carassius auratus The fish were exposed to three doses of glyphosate formulation (5, 10 and 15 ppm) Cyclophosphamide at a single dose of 5 mg/l was used as positive control Analysis of micronuclei, nuclear abnormalities and DNA damage were performed on peripheral erythrocytes sampled at intervals of 48, 96 and 144 h posttreatment Our results revealed significant dose-dependent increases in the frequencies of micronuclei, nuclear abnormalities as well as DNA strand breaks Our findings also confirmed that the alkaline comet assay and nuclear deformations in addition to micronucleus test on fish erythrocytes in vivo are useful tools in determining the potential genotoxicity of commercial herbicides