[Show abstract][Hide abstract] ABSTRACT: Angiotensin II receptor blockers (ARBs) are a new class of drugs for the treatment of hypertension. In this study, we studied the potential genotoxic effects of five ARBs in vivo and in vitro in human peripheral blood lymphocytes (PBLs) by means of the cytokinesis-block micronucleous (CBMN) assay in combination with fluorescence in situ hybridization (FISH) with a centromeric probe. The nuclear division index (NDI) was used as a measure of cytotoxicity. We also analyzed the association between sex, age, duration of treatment and MN formation. The in vivo study was carried out in 55 hypertensive patients. The in vitro study was performed in 10 control individuals by adding the drugs to the culture medium at a final concentration similar to the levels found in plasma in patients. Our results showed a significant increase in the frequencies of MN and binucleated cells with MN (BNMN) in vivo and especially in vitro. We observed variability in the mean frequency of MN and BNMN among the five drugs analyzed. In vivo, patients treated with Candesartan, Telmisartan and Valsartan showed a statistical significant increase in these parameters, while Olmesartan showed the highest effect in vitro. We also found that the drugs inhibit the NDI in vitro and that Eprosartan, Olmesartan and Telmisartan are the ARBs studied with the highest effect in decreasing the proliferation of the cells. FISH analysis revealed no significant difference between patients and controls in the frequency of centromeric signals. A slight variability, without statistical significance, in the frequency of micronuclei with a centromere signal (CN+MN) was found among the different ARBs analyzed, ruling out an aneugenic potential. When accounting for risk factors, we found that in patients there is a positive correlation between MN, BNMN and sex and a negative correlation with duration of treatment.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 04/2014; · 3.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Angiotensin II receptor blockers (ARBs) are a new class of drugs for the treatment of hypertension. In this study, we studied the potential genotoxic effects of five ARBs in vivo and in vitro in human peripheral blood lymphocytes (PBLs) by means of the cytokinesis-block micronucleous (CBMN) assay in combination with fluorescence in situ hybridization (FISH) with a centromeric probe. The nuclear division index (NDI) was used as a measure of cytotoxicity. We also analyzed the association between sex, age, duration of treatment and MN formation. The in vivo study was carried out in 55 hypertensive patients. The in vitro study was performed in 10 control individuals by adding the drugs to the culture medium at a final concentration similar to the levels found in plasma in patients. Our results showed a significant increase in the frequencies of MN and binucleated cells with MN (BNMN) in vivo and especially in vitro. We observed variability in the mean frequency of MN and BNMN among the five drugs analyzed. In vivo, patients treated with Candesartan, Telmisartan and Valsartan showed a statistical significant increase in these parameters, while Olmesartan showed the highest effect in vitro. We also found that the drugs inhibit the NDI in vitro and that Eprosartan, Olmesartan and Telmisartan are the ARBs studied with the highest effect in decreasing the proliferation of the cells. FISH analysis revealed no significant difference between patients and controls in the frequency of centromeric signals. A slight variability, without statistical significance, in the frequency of micronuclei with a centromere signal (CN + MN) was found among the different ARBs analyzed, ruling out an aneugenic potential. When accounting for risk factors, we found that in patients there is a positive correlation between MN, BNMN and sex and a negative correlation with duration of treatment.
[Show abstract][Hide abstract] ABSTRACT: Premature ovarian failure (POF) is defined as cessation of menses before the age of 40. The most significant single gene associated with POF is the Fragile X Mental Retardation 1 gene (FMR1). In the present work we screened women with fertility problems from the Basque Country in order to determine, whether in these women, FMR1 CGG repeat size in the intermediate and premutation range was associated with their pathology, and whether intermediate and premutation carriers had endocrine signs of diminished ovarian function, using the most established measure of ovarian reserve, the gonadotropin FSH. A patient sample of 41 women with ovarian insufficiency and a control sample of 32 women with no fertility problems from the Basque Country were examined. The patient sample was classified into three categories according to the results of the retrospective assessment of their ovarian function. In group 2 of patients, women with irregular cycles, reduced fecundity and FSH levels ≥ 10 IU/l, there is a significant increase in the number of intermediate and premutation FMR1 alleles (35-54 CG repeats). In group 3 of patients, women with amenorrhea for at least four consecutive months and FSH levels ≥ 10 IU/l, a significant increase in the number of intermediate FMR1 alleles (35-54 CGG repeats) was found in patients compared with controls. In this group all the patients had a serum concentration >40 IU/l. The results suggest that in the analyzed Basque sample the FMR1 gene has a role in the aetiology of POF. However, elevated FSH levels are more related to the menstrual cycle pattern than to the CGG repeat size.
[Show abstract][Hide abstract] ABSTRACT: INTRODUCTION AND OBJECTIVES: We studied genotypic and allelic frequencies of polymorphisms that can affect platelet function, namely the Kozak, VNTR and HPA-2 polymorphisms of glycoprotein Ibα, the Pl(A) polymorphism of glycoprotein IIIa and the C807T polymorphism of glycoprotein Ia, in a Portuguese population composed of 227 donors. METHODS: PCR-RFLP was used to assess the Kozak, HPA-2, Pl(A) and C807T polymorphisms. The VNTR polymorphism was discriminated by different weight bands on electrophoresis. RESULTS: All genotypic frequencies were in Hardy-Weinberg equilibrium and do not differ from other Caucasian populations. Genotypic frequencies were 68.3%, 26.9% and 4.8% for Pl(A1/A1), Pl(A1/A2) and Pl(A2/A2) genotypes of the Pl(A) polymorphism, 79.3%, 20.3% and 0.4% for TT, TC and CC genotypes of the Kozak polymorphism, 81.1%, 18.9% and 0.0% for aa, ab and bb genotypes of the HPA-2 polymorphism, 15.4%, 0.9%, 70.5%, 11.5%, 1.3% and 0.4% for BC, BD, CC, CD, DD and CE genotypes of the VNTR polymorphism, and 39.7%, 50.2% and 10.1% for CC, CT and TT genotypes of the C807T polymorphism. CONCLUSIONS: The Portuguese population has now been characterized in terms of major platelet glycoprotein polymorphisms, which will be an important tool for further studies to assess the role of platelet glycoproteins in individual predisposition to prothrombotic conditions and response to antithrombotic therapy.
Revista portuguesa de cardiologia: orgao oficial da Sociedade Portuguesa de Cardiologia = Portuguese journal of cardiology: an official journal of the Portuguese Society of Cardiology 01/2013; · 0.59 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The myocardial perfusion is modified more frequently by coronary atherosclerosis, which can lead to cardiac dysfunction. The allelic variants can induce different phenotypes of left ventricle remodelling. The factors for expression of phenotypes of myocardial blood perfusion are not completely understood. The purpose of this study was to evaluate the influence of single nucleotide polymorphisms of metalloproteinase 3 (MMP3; rs3025058) and metalloproteinase 9 (MMP9; rs3918242) genes in the myocardial blood perfusion, and to determine the allelic variants that influence the susceptibility of myocardial perfusion abnormalities. Two hundred and five patients underwent myocardial perfusion imaging (MPI) with 99mTc-tetrofosmin in which was carried out for genotyping of MMP3 and MMP9 promoter gene polymorphism. Negative MPI to myocardial ischaemia was defined by absent of myocardial perfusion defects (MPD) and positive MPI to myocardial ischaemia was defined by presence of one or more reversible and/or irreversible MPD. Analysis of MPI allowed the identification of 122 patients with negative MPI and 83 with positive MPI. MPD were more prevalent and irreversible nature in 6A homozygotes than 5A MMP3 allele carries (MPD – 6A6A: 52.6%, 5A allele: 37.4%, p>0.05; irreversible MPD – 6A6A: 34.2%, 5A allele: 19.6%, p>0.05). All 6A homozygote patients with myocardial infarction or those who underwent coronary revascularisation had MPD (p p>0.05, non-unique contribution). The results of this study suggest that the allelic variation of MMP3 gene can have an important role in myocardial remodelling, and appoint the 6A6A genotype as a marker of alterations in myocardial blood perfusion, especially remodelling associated with irreversible MPD. This study also showed that the allelic variation of MMP9 gene had no significant influence in myocardial perfusion.
Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization. 01/2013; 1(3).
[Show abstract][Hide abstract] ABSTRACT: Fragile X Syndrome (FXS, MIM 309550) is mainly due to the expansion of a CGG trinucleotide repeat sequence, found in the 5' untranslated region of the FMR1 gene. Some studies suggest that stable markers, such as single nucleotide polymorphisms (SNPs) and the study of populations with genetic identity, could provide a distinct advance to investigate the origin of CGG repeat instability. In this study, seven SNPs (WEX28 rs17312728:G>T, WEX70 rs45631657:C>T, WEX1 rs10521868:A>C, ATL1 rs4949:A>G, FMRb rs25707:A>G, WEX17 rs12010481:C>T and WEX10 ss71651741:C>T) have been analyzed in two Basque valleys (Markina and Arratia). We examined the association between these SNPs and the CGG repeat size, the AGG interruption pattern and two microsatellite markers (FRAXAC1 and DXS548). The results suggest that in both valleys WEX28-T, WEX70-C, WEX1-C, ATL1-G, and WEX10-C are preferably associated with cis-acting sequences directly influencing instability. But comparison of the two valleys reveals also important differences with respect to: (1) frequency and structure of "susceptible" alleles and (2) association between "susceptible" alleles and STR and SNP haplotypes. These results may indicate that, in Arratia, SNP status does not identify a pool of susceptible alleles, as it does in Markina. In Arratia valley, the SNP haplotype association reveals also a potential new "protective" factor.
Annals of Human Genetics 01/2012; 76(2):110-20. · 2.22 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The antihypertensive drug atenolol was found to induce chromosome loss, detected as micronuclei in the peripheral lymphocytes of treated patients. The fundamental question which chromosomes the micronuclei were derived from remains to be answered. Analysis of structural chromosomal aberrations (CAs) and expression of fragile sites (FS) were pursued in this study. They revealed a significantly higher incidence of chromosomal aberrations (chromatid and chromosome breaks) in patients compared with controls, where 10 FS emerged as specific. Also, the band 17q12-21, where known fragile sites have not been reported, was only expressed in atenolol-treated patients. Fluorescence in situ hybridization using chromosome-specific probes revealed the preferential involvement of chromosomes 7, 11, 17 and X in the micronuclei (MN) of patients. The results also suggest a correlation between chromosomal fragility and content of MN, and support the findings for a linkage between hypertension and a locus on chromosome 17.
Mutation Research/Fundamental and Molecular Mechanisms of Mutagenesis 11/2009; 695(1-2):46-54. · 3.90 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fragile X syndrome is the most common form of inherited mental retardation. The molecular basis is usually the unstable expansion of a CGG repeat in the FMR1 gene. We previously analyzed a sample of two Basque valleys. In the present work we extend the study to another five isolated valleys. The results show that differences in factors implicated in CGG repeat instability--CGG repeat size, XS548/FRAXAC1 haplotypes, and AGG interspersion pattern-are present in the Basque populations analyzed.
Human Biology 01/2009; 80(6):593-600. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fragile X Syndrome (FXS) is associated with an unstable CGG repeat sequence in the 5' untranslated region in the first exon of the FMR1 gene which resides at chromosome position Xq27.3 and is coincident with the fragile site FRAXA. The CGG sequence is polymorphic with respect to size and purity of the repeat. Interpopulation variation in the polymorphism of the FMR1 gene and consequently, in the predisposition to FXS due to the prevalence of certain unstable alleles has been observed. Spanish Basque population is distributed among narrow valleys in northeastern Spain with little migration between them until recently. This characteristic may have had an effect on allelic frequency distributions. We had previously reported preliminary data on the existence of FMR1 allele differences between two Basque valleys (Markina and Arratia). In the present work we extended the study to Uribe, Gernika, Durango, Goierri and Larraun, another five isolated valleys enclosing the whole area within the Spanish Basque region. We analyzed the prevalence of FMR1 premutated and intermediate/grey zone alleles. With the aim to complete the previous investigation about the stability of the Fragile X CGG repeat in Basque valleys, we also analyzed the existence of potentially unstable alleles, not only in relation with size and purity of CGG repeat but also in relation with DXS548 and FRAXAC1 haplotypes implicated in repeat instability. The data show that differences in allele frequencies as well as in the distribution of the mutational pathways previously identified are present among Basques. The data also suggest that compared with the analyzed Basque valleys, Gernika had increased frequency of susceptibility to instability alleles, although the prevalence of premutation and intermediate/grey zone alleles in all the analyzed valleys was lower than that reported in Caucasian populations.
Current Genomics 06/2008; 9(3):191-9. · 2.48 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The aim of the present study was to assess if the presence of survivin mRNA in exfoliated cells present in urine samples can be a reliable marker of the presence of bladder tumour and recurrence.
Urine samples from 30 patients with superficial urothelial cell carcinomas (UCC) were collected prior to transurethral resection (TUR) of the tumour and in the first routine follow-up, three months after TUR. Detection of survivin mRNA was performed by reverse transcription-polymerase chain reaction (RT-PCR).
No correlation was observed between survivin detection and the clinicopathological variables analysed, nevertheless, when patients were grouped into low-grade (G1) and high-grade (G2+G3) tumours, statistically significant differences were found between both groups (p=0.04). When we analysed the results of survivin detection and urinary cytology together, we observed that informative cases rose from 27.8% to 44.4%. Also, Kaplan-Meier curves for patients with negative cytology in the first followup, categorised according to survivin detection, revealed that survivin mRNA positive cases recurred earlier than negative ones.
From our results we can conclude that detection of survivin expression can be a reliable tumour marker, but more studies are needed to clarify the potential of survivin to predict recurrences. These results showed that survivin detection in combination with conventional urinary cytology can be a useful tool to increase the sensitivity in detecting the presence of a recurrence after TUR.
Clinical and Translational Oncology 12/2007; 9(11):731-6. · 1.28 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Digital patterns of a sample of monozygotic and dizygotic twins were analyzed to obtain heritability values for the four basic types of patterns: arch, tented arch, loops, and whorls. Loops have been separated according to their orientation radial or ulnar. To carry out this study, we used the Holzinger and Clark indices. The results show highest concordances for monozygotic twins except for ulnar loops of the left hand and radial ones of the right hand. Different values of heritability were found for the right and left hands, with finger I having the highest values.
American Journal of Human Biology 05/2005; 3(1):11 - 15. · 2.34 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The expansion of a trinucleotide repeat [CGG]n located in the FMR1 X-linked gene is the main cause of fragile X syndrome, the most common form of inherited mental retardation. We have analyzed the factors known, to date, to influence the instability of the repeat in 158 normal X chromosomes from the Spanish Basque population. These factors included length of the repeat, AGG interspersion pattern, length of uninterrupted CGG and DXS548-FRAXAC1 markers associated haplotype. Previous investigations on Basques showed an absence of this disorder among mentally retarded individuals that was likely due to a low prevalence of large CGG alleles and the presence of AGG interruptions on them. The present report suggests that, although the frequency of large alleles is low and they do maintain AGG interruptions, different mutational pathways that might lead to fragile X syndrome could be occurring among Basques. These pathways mainly include alleles with internal sequences 9 + 9 + n and 9 + 12 + 9 that show fragile X associated haplotypes. Besides, the lack of the most proximal AGG interruption, proposed recently as a novel factor involved in CGG repeat instability, was highly identified among alleles with long pure CGG tracts, which showed an internal sequence n + 9. The data suggest that, despite the lower incidence of large alleles, the prevalence of potentially unstable alleles among Basques is similar to that of other Caucasian populations and that these alleles could become fragile X chromosomes.
American Journal of Medical Genetics Part A 08/2004; 128A(3):250-5. · 2.30 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Approximately 80% of bladder tumors are urothelial superficial papillary carcinomas (USPC). Despite a generally good prognosis, these tumors have a strong propensity to recur and about 1/3 of them compared to disease progression. Histological assessment of these superficial tumors is not sufficiently discriminator in predicting prognosis; therefore, we decided to evaluate the prognostic significance of p53 and Ki-67 immunoexpression in low-grade (GI-II) USPC in order to predict the potential outcome of these tumors. P53 and Ki-67 immunoexpression were studied in function of recurrence-free and progression-free survival in 159 primary superficial bladder tumors. A prognostic risk model based on grade, stage and multifocality was also evaluated. P53 accumulation was significantly related to tumor progression (p=0.006). High Ki-67 index (>/=18%) and multifocality were significantly related to recurrence (both p=0.0001) and progression-free survival (both p=0.0001) and were independent prognostic factors in the multivariate analysis. The prognostic risk model based on grade, stage and multifocality was not an efficient discriminator of outcome. Adding the Ki-67 index into the risk model, single pTa/T1-GI Ki-67 positive tumors, usually classified as low risk, were reclassified as of intermediate risk. After this reclassification, the risk group model identified a subgroup of pTa/T1-G1 with a high risk of recurrence and progression. Ki-67 index is a reliable prognostic marker in urothelial superficial bladder carcinoma and, when included into a risk profile classification of the low-grade USPC, the accuracy of the prognostic discrimination is enhanced.
International Journal of Cancer 06/2003; 105(2):267-72. · 6.20 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: The present study involves the evaluation of digital dermatoglyphic traits of 2185 unrelated individuals (1152 females and 1033 males) from 17 natural valleys of the four Basque provinces (Vizcaya, Guipúzcoa, Navarra, and Alava) in the Spanish Basque Country. Univariate intervalley and between-sex comparisons were carried out by means of chi-square contingency analysis for pattern types and by means of one-way analysis of variance for ridge counts. Multivariate intervalley comparison was carried out by means of correspondence analysis for pattern types and by principal component analysis for ridge counts. The results of this study are notable for the following findings: (1) in general, all variables are significantly heterogeneous among valley populations; (2) there was a greater differentiation among the valley populations than between sexes in one valley population; (3) affinities among the intervalley populations depend on the variables considered; (4) the valley populations from Vizcaya resemble those from the Pyrenees; (5) based on interprovince comparisons, the Vizcaya and Navarra samples are the closest: (6) in general, the valley samples from Alava are the worst clustered; (7) the universality of dermatoglyphic component structure fits better in males.
Human Biology 05/2003; 75(2):265-91. · 1.52 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Fragile X syndrome is associated with an unstable CGG repeat sequence in the 5' untranslated region of the first exon of the FMR1 gene. The present study involved the evaluation of factors implicated in CGG repeat stability in a normal sample from two Basque valleys (Markina and Arratia), to discover whether the Basque population shows allelic diversity and to identify factors involved, by using the data in conjunction with previous findings. The study was based on a sample of 204 and 58 X chromosomes from the Markina and Arratia valleys, respectively. The CGG repeat, the AGG interspersion and two flanking microsatellite markers, FRAXAC1 and DXS548, were examined. In the Markina valley, gray zone alleles (> or =35 CGG repeats) were associated with anchoring AGGs, with the longest 3' pure CGG repeats of the valley (=15), with the 5' instability structure 9+n and with one principal fragile X FRAXAC1-DXS548 haplotype 42-50. In the Arratia valley, gray zone alleles (> or =35 CGG repeats) showed the highest frequency among the Basque samples analyzed, and were associated with anchoring AGGs, with the longest 3' pure repeats (> or =20), with the 5' instability structure 9+n and with one "normal" FRAXAC1-DXS548 haplotype 38-40 (these data from Arratia suggest the existence of a "protective" haplotype). The results showed, on the one hand, differences between Markina and Arratia in factors implicated in CGG repeat instability and, on the other hand, a great similarity between the general Basque sample from Biscay and the Markina valley.
[Show abstract][Hide abstract] ABSTRACT: Cell-cycle regulatory proteins are important indicators in determining progression trough the cell-cycle and progression to invasive cancer in patients presenting with superficial bladder cancer. We performed an immunohistochemical study in order to evaluate the prognostic value of the expression of p16, p27, pRb, p53 and Ki-67 in superficial grade I and II papillary urothelial cell carcinoma of the bladder.
p16, p27, p53, pRb and Ki-67 immunoexpression was studied in 14 pTa, 35 pT1a and 7 pT1b bladder tumours at presentation and at recurrence of their tumours. The recurrence-free survival and the progression-free survival were analysed according to these regulatory cell-cycle proteins expression.
For survival in univariate analysis a high Ki-67 labelling index was a poor prognostic factor for recurrence-free and progression-free survival (P=0.0014 and P=0.012, respectively). Ki-67 labelling index was also an independent recurrence-free survival prognostic factor (P=0.0005). The p16, p27, p53 and pRb immunoreactivity was not significantly associated with recurrence or progression rate in this group of bladder carcinomas.
These data suggest that the Ki-67 labelling index can be a reliable marker in predicting recurrence and/or progression in superficial low-grade bladder carcinomas and may be relevant in planning adjuvant therapy.
European Journal of Surgical Oncology 03/2003; 29(1):74-80. · 2.61 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Superficial urothelial cell carcinoma (UCC) is a heterogeneous group of neoplasia with an unpredictable clinical course. Numerical alterations of chromosomes 7, 9 and 17 in superficial and invasive UCCs were analysed to evaluate the importance of chromosome instability in the progression of these tumours. Our sample consisted of 75 patients (47 with superficial and 28 with invasive bladder tumours). In situ hybridization using centromeric probes for chromosomes 7, 9 and 17 was done for the chromosome analysis in paraffin-embedded tissues. From the results obtained it can be concluded that losses of genetic material seem to be important early events in the carcinogenesis of the urothelium, but during progression of UCCs there seems to be a selection of those cells with gains of genetic material. This chromosome instability may be due to the acquisition of mechanisms involved in aneuploidization, namely p53 function disorders.
[Show abstract][Hide abstract] ABSTRACT: Numerous studies have shown there is consistent evidence implicating genetic factors in the etiology of autism. In some cases chromosomal abnormalities have been identified. One type of these abnormalities is gaps and breaks nonrandomly located in chromosomes, denominated fragile sites (FS). We cytogenetically analyzed a group of autistic individuals and a normal population, and we examined the FS found in both samples with the aim of (1) comparing their FS expression, (2) ascertaining whether any FS could be associated with our autistic sample, and (3) examining if there are differences between individual and pooled-data analyses. Different statistical methods were used to analyse the FS of pooled and individual data. Our results show that there are statistically significant differences in the spontaneous expression of breakages between patients and controls, with a minimal sex difference. Using the method for pooled data, eight autosomal FS have preferential expression in patients and five patients were found to be positive at FS Xq27.3. With the method per-individual analysis, four FS emerged as specific in our autistic sample. Inferences of FS from pooled data were different from those of individual data. The findings suggest that although analysis of pooled data is necessitated by the problem of sparse data, analysis of single individuals is essential to know the significance of FS in autism.
[Show abstract][Hide abstract] ABSTRACT: The aim of this work was a study of the genotoxic potential of chronic long-term therapy with the antihypertensive drug nimodipine by measures of sister chromatid exchanges (SCE) and micronuclei (MN) in peripheral human lymphocytes of patients with long-term exposure to this drug. Peripheral human lymphocytes of control individuals exposed in vitro to nimodipine were also studied to assess the effect of the drug itself. Fluorescence in situ hybridization (FISH) with a centromeric probe was performed to determine the origin of the induced MN. The in vivo study was carried out on five patients under antihypertensive treatment with nimodipine. The in vitro study was performed on five control individuals by adding the drug to the culture medium at a final concentration similar to the levels found in plasma (controls/medium). The in vivo study showed no genotoxic effects of long-term therapy with nimodipine because the frequencies of SCE and MN in exposed patients did not show significant differences as compared with control individuals. A statistically significant increase in the frequency of MN was detected in controls/medium as compared with control individuals without the drug. FISH analysis revealed statistically significant differences with respect to the frequency of centromeric signals in nimodipine-induced MN in vitro. With regard to the in vivo results, chronic long-term therapy with nimodipine is not associated with increased genotoxicity. The differing results in vivo and in vitro could be due to extensive metabolism of nimodipine, indicating that the cytogenetic effect observed was due to the drug itself rather than its metabolites or to an adaptive response to nimodipine in vivo.