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Biomedical subjects

M Valverde

Publications and source records attributed to M Valverde.

At least 19 recordsLinked to original sources
PubMed2006

DNA damage in outdoor workers occupationally exposed to environmental air pollutants.

BACKGROUND: Health concerns about the exposure to genotoxic and carcinogenic agents in the air are particularly significant for outdoor workers in less developed countries. AIMS: To investigate the association between personal exposure to a group of air pollutants and severity of DNA damage in outdoor workers from two Mexican cities. METHODS: DNA damage (Comet assay) and personal exposure to volatile organic compounds, PM(2.5), and ozone were investigated in 55 outdoor and indoor workers from México City and Puebla. RESULTS: In México City, outdoor workers had greater DNA damage, reflected by a longer tail length, than indoor workers (median 46.8 v 30.1 mum), and a greater percentage of highly damaged cells (cells with tail length > or =41 microm); in Puebla, outdoor and indoor workers had similar DNA damage. There were more alkali labile sites in outdoor than indoor workers. The DNA damage magnitude was positively correlated with PM(2.5) and ozone exposure. Outdoor and indoor workers with > or =60% of highly damaged cells (highly damaged workers) had significantly higher exposures to PM(2.5), ozone, and some volatile organic compounds. The main factors associated with the highly damaged workers were ozone, PM(2.5), and 1-ethyl-2-methyl benzene exposure. CONCLUSIONS: With this approach, the effects of some air pollutants could be correlated with biological endpoints from the Comet assay. It is suggested that the use of personal exposure assessment and biological endpoints evaluation could be an important tool to generate a more precise assessment of the associated potential health risks.

Adolescent↗
PubMed2004

Genotoxic differences by sex in nasal epithelium and blood leukocytes in subjects residing in a highly polluted area.

We describe differences by sex in genotoxic damage found in a population of medical students exposed to a highly oxidative atmosphere, compared with a control group, measured by the single-cell gel electrophoresis assay and histological changes in nasal epithelium smears. Cells were obtained from the nasal epithelium and blood leukocytes. Higher DNA damage in nasal cells and leukocytes was found in males compared to females and control subjects. The percentage of squamous metaplastic changes in the nasal epithelium was also higher in males compared with females and controls. The co-mutation of normal nasal epithelium by squamous cells might modify its protective function in the nose, increasing the risk of damage to the lower respiratory tract. Although, as medical students, males and females were exposed to the same environment and activity patterns, male genotoxicity damage was higher in control and exposed subjects. More research should be done in order to identify direct or indirect sexual hormone intervention.

Adult↗
PubMed2001

Is the capacity of lead acetate and cadmium chloride to induce genotoxic damage due to direct DNA-metal interaction?

Even though the toxic effects of lead and cadmium compounds have been studied over many years, inconsistent results have been obtained about their mutagenic, clastogenic and carcinogenic properties. However, these metals are considered to be potential human carcinogens. The mechanism of metal-induced carcinogenesis is still unknown, but one possible pathway may involve the interaction of metals with DNA, either directly or indirectly. In this work we explore the capacity of lead, cadmium or a mixture of both metals to interact with acellular DNA, by employing a variant of the comet assay. Our results, using low non-cytotoxic metal concentrations (0.01, 0.1 and 1.0 microM) with the standard protocol for the acellular assay, showed an induction of DNA damage in cells of all organs studied; however, basal DNA damage was different in each organ. To confirm that we were working with pure DNA, proteinase K was added to the lysis solution. With this enriched-lysis solution we found a negative response in the induction of DNA damage in cells derived from the liver, kidney and lung of CD-1 male mice. To support the results obtained by the enriched-acellular assay, we studied the capacity of lead and cadmium (0.1 microM) to induce breaks in pooled genomic DNA in cells of the same organs, with negative results. Consistent with these findings, these metals do not induce DNA breaks in the plasmid pUSE amp+. On the whole, we did not detect direct induction of DNA strand breaks by lead acetate, cadmium chloride or a mixture of both metals, all at low non-cytotoxic concentrations. However, we found an induction of lipid peroxidation and an increase in free radical levels in the different organs of CD-1 male mice after inhalation of lead acetate (0.0068 microg/cc) or cadmium chloride (0.08 microg/cc) for 1 h, suggesting the induction of genotoxicity and carcinogenicity by indirect interactions, such as oxidative stress.

Animals↗
PubMed2000

Evaluation of DNA damage in exfoliated tear duct epithelial cells from individuals exposed to air pollution assessed by single cell gel electrophoresis assay.

The search for relevant target cells for human monitoring purposes has increased during the last few years. Cells such as sperm, buccal or nasal and gastric epithelium are being used. In this study, we report the use of exfoliated tear duct epithelial cells as a potential material for human biomonitoring studies, since these cells are a target for environmental pollutants. We employed the alkaline single cell gel electrophoresis (SCGE) assay to evaluate for differences in the basal level of DNA damage between young adults from the south (exposed mainly to high levels of ozone) and from the north (exposed principally to hydrocarbons) regions of Mexico City. We found an increase in DNA migration in tear duct epithelial cells from individuals who live in the southern part of the city compared to those living in the northern part. Moreover, young people who live in the southwest part of the city with the highest values of ozone presented the highest values of DNA damage. These results show the feasibility of using exfoliated tear duct epithelial cells in human biomonitoring studies.

Adolescent↗
PubMed2000

Accumulation of DNA damage in the organs of mice deficient in gamma-glutamyltranspeptidase.

We have used a differential alkaline single cell gel electrophoresis assay of DNA ("omet assay" at pH 13 and 12.3) to evaluate DNA damage as a function of age in mice with an inherited defect in gluthathione (GSH) metabolism. The mice are homozygous null for gamma-glutamyltranspeptidase (GGT), the enzyme responsible for initiating the catabolism of GSH, and paradoxically have reduced levels of GSH and cysteine in many organs. We found an accumulation of DNA damage in lung, liver and kidney in these mice as a function of age. The largest differences were in assays run at pH 13, suggesting that the accumulation of apurinic/apryrimidinic (AP) sites and oxidative damage of DNA was largely responsible. In contrast, little if any accumulation of these lesions was detected in wild-type mice. Although these findings do not allow a precise analysis of the molecular basis of damage accumulation in GGT-deficient mice, they implicate low GSH and cysteine levels as a cause of accumulative DNA damage in the intact mammal.

Aging↗
PubMed2000

Induction of genotoxicity by cadmium chloride inhalation in several organs of CD-1 mice.

In recent years, the concentration of metals in the environment has increased significantly. Metal compounds, as a group, are among the best-documented human carcinogens, but the mechanisms by which they act are not completely understood. In the present study a cadmium inhalation model in mice was implemented in order to detect the induction of genotoxic damage as single-strand breaks and alkali-labile sites in several organs (nasal epithelial cells, lung, whole blood, liver, kidney, bone marrow, brain and testicle) using the single cell gel electrophoresis (SCGE) or Comet assay. We found differences among the studied organs after a single and subsequent inhalations: in the organs analyzed we observed that major DNA damage was induced after a single inhalation; in subsequent inhalations there was a tendency to maintain the same magnitude of damage or in some cases it decreased. A correlation between length of exposure, DNA damage and metal tissue concentration was found. These results suggest that cadmium chloride inhalation induces systemic DNA damage; some organs showed less damage than others (liver, brain, etc.) and this finding could be as a consequence of the capacity to remove the damage induced by long periods of exposure, possibly because of the induction of detoxifying mechanisms such as induction of metallothionein.

Administration, Inhalation↗
PubMed1999

Single cell gel electrophoresis assay: methodology and applications.

The single cell gel electrophoresis or Comet assay is a sensitive, reliable, and rapid method for DNA double- and single-strand breaks, alkali-labile sites and delayed repair site detection, in eukaryotic individual cells. Given its overall characteristics, this method has been widely used over the past few years in several different areas. In this paper we review the studies published to date about the principles, the basic methodology with currently used variations. We also explore the applications of this assay in: genotoxicology, clinical area, DNA repair studies, environmental biomonitoring and human monitoring.

Animals↗
PubMed1999

Genotoxic studies of vanadium pentoxide (V(2)O(5)) in male mice. II. Effects in several mouse tissues.

Vanadium pentoxide (V2O5) was tested for its ability to induce genotoxic damage in six different organs (liver, kidney, lung, spleen, heart, and bone marrow) of mice by using the alkaline Single Cell Gel Electrophoresis (SCGE) assay. Animals were sacrificed 24 h after i.p. administration of the vanadium pentoxide of 23.0, 11.5, or 5.75 microg/g (corresponding to the LD50, 1/2 LD50 and 1/4 LD50, respectively). In all tissues and organs evaluated (except for bone marrow), V2O5 increased the number of cells with damage. Our results showed that i.p. injection of V2O5 induced DNA damage in different organs and tissues, and that this kind of damage can be observed even 24 h after treatment. The analysis of DNA migration and the distribution of DNA damage showed that there are differences in sensitivity between organs and tissues to this compound. In addition the sensitivity of SCGE assay allows the detection of long term DNA damage and the possibility to compare it in various tissues and target organs.

Animals↗
PubMed1999

The application of single cell gel electrophoresis or Comet assay to human monitoring studies.

OBJECTIVE: In the search of new human genotoxic biomarkers, the single cell gel electrophoresis assay has been proposed as a sensible alternative. MATERIAL AND METHODS: This technique detects principally single strand breaks as well as alkali-labile and repair-retarded sites. RESULTS: Herein we present our experience using the single cell gel electrophoresis assay in human population studies, both occupationally and environmentally exposed. CONCLUSIONS: We discuss the assay feasibility as a genotoxic biomarker.

Biomarkers↗
PubMed1998

Analysis of the DNA damage induced by praziquantel in V-79 Chinese hamster fibroblasts and human blood cells using the single-cell gel electrophoresis assay.

The analysis of the genotoxicity of praziquantel, an effective antihelminthic widely used in countries where parasitic infections are still serious public health problems, has been extensively performed using diverse in vitro and in vivo assays and endpoints. However, results are not conclusive, since reports to date indicate either praziquantel is mutagenic, comutagenic, or even antimutagenic. In the present work, the clastogenic potential of praziquantel was investigated in V-79 Chinese hamster fibroblasts and human peripheral blood using a sensitive technique such as the single-cell electrophoresis assay. Results indicate that even though praziquantel induced DNA single-strand breaks both in V-79 cells and unstimulated human leukocytes, this effect was not translated into persistent DNA damage, since neither SCE nor HPRT mutations were induced. This suggests that the effect observed in the SCGE assay is an early event not closely related to praziquantel mutagenicity, because this DNA damage could be efficiently repaired.

Adult↗
PubMed1997

[Gestational diabetes: the use of an intensive treatment program at the regional level].

In this study the results are shown of the application of an intensified treatment program of Gestational Diabetes (GD) in a regional setting. From January 1991 to June 1995, 115 women with GD were attended at Mútua Hospital in Terrassa; 62.6% of them required insulin to optimize the metabolic control. When insulin dependent women were compared with non insulin dependent women, diagnosis was earlier; age, progestational age, serum glucose in the O'Sullivan test and diagnostic basal serum glucose in oral overload (GOO) were higher. Regarding perinatal results, the incidence of gestational hypertensive disturbances, hydramnios, and urinary tract infections were 7%, 1.7%, and 8%, respectively. Perinatal mortality was 0.86%. Delivery occurred after 37 weeks in 96.5% of cases and the cesarean section was performed in 26%; nevertheless, this rate was similar to that in the obstetric population attended at this institution (25%). Birth weight was high for gestational age in 7.8% of newborns (NB) and low in 2.5%. Factors associated with fetal weight included progestational maternal weight, ponderal increase during pregnancy and metabolic control (HbA1c). The present study suggests that the application of an intensified treatment program for GD can be carried out in a regional setting and with overall successful results.

Adult↗
PubMed1997

DNA damage in leukocytes and buccal and nasal epithelial cells of individuals exposed to air pollution in Mexico City.

There is an increased interest in using biological markers to monitor individuals for possible exposure to environmental toxicants. Test systems which permit the sensitive detection of DNA damage and DNA repair are critically important in such studies. The single cell gel electrophoresis (SCG) assay is a rapid and a sensitive method for the evaluation of DNA damage at the single cell level, providing information on the occurrence of DNA single-strand breaks and alkali labile sites using alkaline conditions. In this study, the differences in the basal level of DNA damage between young adults from the south (exposed principally to high levels of ozone) and young adults from the north (exposed principally to hydrocarbons and particles) of Mexico City were investigated by the SCG assay using three different cell types (leukocytes and nasal and buccal epithelial cells). We found an increased DNA migration in blood leukocytes and nasal cells from individuals who live in the southern part of the city compared to those living in the northern part; however, no differences were observed for buccal epithelial cells. These results show the feasability of using the SCG assay to evaluate DNA damage in different tissues and its great potential for use in the monitoring of humans potentially exposed to genotoxic pollutants.

Adult↗
PubMed1996

DNA damage in exfoliated buccal cells of smokers assessed by the single cell gel electrophoresis assay.

The alkaline single-cell gel electrophoresis assay or comet assay is a sensitive and rapid method for DNA strand breaks and detection of alkali labile sites at the single cell level, it further provides information on the presence of damage among individual cells. In this paper we explore the use of this technique utilizing exfoliated buccal mucosa cells from non-smokers (9 donors) and smokers (11 donors). The extent of DNA image length was found to be significantly increased in the smoker group (89.30 +/- 16.18 microns) than in the non-smoker group (52.01 +/- 10.43 microns). Our results indicate that the single-cell gel electrophoresis assay could be applied to human monitoring using exfoliated buccal epithelial cells.

Adult↗
PubMed1996

Genotoxic effects of bistratene A on human lymphocytes.

Bistratene A, a toxin isolated from the colonial ascidian Lissoclinum bistratum causes a decrease in mitotic index and retardation of lymphocyte proliferation kinetics when it is added at 48 h to 72-h human lymphocyte cultures. In the same cultures, the incidence of sister chromatid exchanges was not altered by this compound. We also observed an increase in the number of polyploid cells in the cultures, and alterations of the beta-tubulin organization by immunocytochemistry with an antibody against beta-tubulin. Bistratene A induces DNA damage in a dose-dependent fashion in leukocytes, as measured by the alkaline single cell gel electrophoresis assay. These results show that bistratene A interferes with microtubule assembly, is cytotoxic and cytostatic, and that it causes DNA damage.

Acetamides↗
PubMed1996

Genotoxicity of vanadium pentoxide evaluate by the single cell gel electrophoresis assay in human lymphocytes.

Vanadium compounds are extensively used in modern industry and occupational exposure to high doses of Vanadium is quite common. In this study, the genotoxicity of vanadium pentoxide (V2O5) was evaluated directly in whole blood leukocytes and in human lymphocyte cultures using the single-cell gel electrophoresis assay (Comet Assay) to detect DNA damage expressed as DNA strand breaks and alkali labile sites. This chemical produces a clear dose-response in DNA migration in whole blood leukocytes and a significative positive effect only with the highest tested concentration in human lymphocyte cultures. After different recovery times the level of DNA damage returned to the control values. These results indicate that V2O5 is capable to induce DNA single-strand breaks and/or alkali-labile damage.

Adult↗