Diabetes Drug Discovery: hIAPP1-37 Polymorphic Amyloid Structures as Novel Therapeutic Targets.

Human islet amyloid peptide (hIAPP1-37) aggregation is an early step in Diabetes Mellitus. We aimed to evaluate a family of pharmaco-chaperones to act as modulators that provide dynamic interventions and the multi-target capacity (native state, cytotoxic oligomers, protofilaments and fibrils of hIAPP1-37) required to meet the treatment challenges of diabetes. We used a cross-functional approach that combines in silico and in vitro biochemical and biophysical methods to study the hIAPP1-37 aggregation-oligomerization process as to reveal novel potential anti-diabetic drugs. The family of pharmaco-chaperones are modulators of the oligomerization and fibre formation of hIAPP1-37. When they interact with the amino acid in the amyloid-like steric zipper zone, they inhibit and/or delay the aggregation-oligomerization pathway by binding and stabilizing several amyloid structures of hIAPP1-37. Moreover, they can protect cerebellar granule cells (CGC) from the cytotoxicity produced by the hIAPP1-37 oligomers. The modulation of proteostasis by the family of pharmaco-chaperones A-F is a promising potential approach to limit the onset and progression of diabetes and its comorbidities.

Breast cancer cell line MDA-MB-231 miRNA profile expression after BIK interference: BIK involvement in autophagy.

B-cell lymphoma 2 (BCL2)-interacting killer (apoptosis inducing) (BIK) has been proposed as a tumor suppressor in diverse types of cancers. However, BIK's overexpression in breast cancer (BC) and in non-small lung cancer cells (NSCLCs), associated with a poor prognosis, suggests its participation in tumor progression. In this study, we evaluated the global expression pattern of microRNAs (miRNAs), messenger RNA (mRNA) expression changes in autophagy, and autophagic flux after BIK interference. BIK gene expression was silenced by small interfering RNA (siRNA) in BC cell MDA-MB-231, and BIK interference efficiency was tested by real-time PCR and by Western blotting. BIK expression levels decreased by 75 ± 18 % in the presence of 600 nM siRNA, resulting in the abolishment of BIK expression by 94 ± 30 %. BIK interference resulted in the overexpression of 17 miRNAs that, according to the DIANA-miRPath v3.0 database, are mainly implied in the control of cell signaling, gene expression, and autophagy. The autophagy array revealed downregulation of transcripts which participate in autophagy, and their interactome revealed a complex network, where hepatocyte growth factor-regulated tyrosine kinase substrate (HGS), α-synuclein (SNCA), unc-51-like autophagy activating kinase 1/2 (ULK1/2), and mitogen-activated protein kinase 3 (MAPK3) were shown to be signaling hubs. LC3-II expression-an autophagy marker-was increased by 169 ± 25 % after BIK interference, which indicates the involvement of BIK in autophagy. Altogether, our results indicate-for the first time-that BIK controls the expression of miRNAs, as well as the autophagic flux in MDA-MB-231 cells.

Involvement of multiple cellular pathways in regulating resistance to tamoxifen in BIK-suppressed MCF-7 cells.

Majority of women with estrogen receptor (ER)-positive breast cancers initially respond to hormone therapies such as tamoxifen (TAM; antagonist of estrogen). However, many tumors eventually become resistant to TAM. Therefore, understanding the various cellular components involved in causing resistance to TAM is of paramount importance in designing novel entities for efficacious hormone therapy. Previously, we found that suppression of BIK gene expression induced TAM resistance in MCF-7 breast cancer cells. In order to understand the response of these cells to TAM and its association with resistance, a microarray analysis of gene expression was performed in the BIK-suppressed MCF-7 cells and compared it to the TAM-only-treated cells (controls). Several genes participating in various cellular pathways were identified. Molecules identified in the drug resistance pathway were 14-3-3z or YWHAZ, WEE1, PRKACA, NADK, and HSP90AA 1. Further, genes involved in cell cycle control, apoptosis, and cell proliferation were also found differentially expressed in these cells. Transcriptional and translational analysis of key molecules such as STAT2, AKT 3, and 14-3-3z revealed similar changes at the messenger RNA (mRNA) as well as at the protein level. Importantly, there was no cytotoxic effect of TAM on BIK-suppressed MCF-7 cells. Further, these cells were not arrested at the G0-G1 phase of the cell cycle although 30 % of BIK-suppressed cells were arrested at the G2 phase of the cycle on TAM treatment. Furthermore, we found a relevant interaction between 14-3-3z and WEE1, suggesting that the cytotoxic effect of TAM was prevented in BIK-suppressed cells because this interaction leads to transitory arrest in the G2 phase leading to the repair of damaged DNA and allowing the cells to proliferate.

Clinical and molecular characterization of a patient with 15q21.2q22.2 deletion syndrome.

We report on a 16-year-old girl with a complex phenotype, including intellectual disability, facial dysmorphisms, and obesity. During her infancy, she presented with weak sucking, global developmental delay, and later with excessive eating with central obesity. The girl was clinically diagnosed with probable Prader-Willi syndrome. Chromosomal analysis showed a de novo deletion 46,XX,del(15)(q21q22). However, the use of the Affymetrix CytoScan HD Array defined the exact breakpoints of the deleted 15q21q22 region. The imbalance, about 10.5 Mb in size, is to date the second largest deletion ever described in this chromosomal region. In addition, our patient carries a microdeletion in the 1q44 region and a gain in 9p24. The array result was arr[hg19] 9p24.1(6,619,823-6,749,335)×3, 1q44(248,688,586-248,795,277)×1, 15q21.2 q22.2(50,848,301-61,298,006)×1. Although our patient presents additional chromosomal alterations, we provide a correlation between the clinical findings and the phenotype of the 15q21 deletion syndrome.

Prevalence of HMTV in breast carcinomas and unaffected tissue from Mexican women.

BACKGROUND: Breast cancer is a complex multifactorial genetic disease. Among other factors, race and, to an even greater extent, viruses are known to influence the development of this heterogeneous disease. It has been reported that MMTV-like (HMTV) gene sequences with a 90 to 98% homology to mouse mammary tumor virus are found in several populations with a prevalence range of 0 to 74%. In the Mexican population, 4.2% of patients with breast cancer exhibit the presence of HMTV (MMTV-like) sequences. The aim of this study was to evaluate the presence and current prevalence of retroviral HMTV (MMTV-like) sequences in breast cancer in Mexican women. METHODS: We used nested PCR and real-time PCR with a TaqMan probe. As a positive control, we used the C3H MMTV strain inserted into pBR322 plasmid. To confirm that we had identified the HMTV sequences, we sequenced the amplicons and compared these sequences with those of MMTV and HMTV (GenBank AF033807 and AF346816). RESULTS: A total of 12.4% of breast tumors were HMTV-positive, and 15.7% of the unaffected tissue samples from 458 patients were HMTV-positive. A total of 8.3% of the patients had both HMTV-positive tumor and adjacent tissues. The HMTV-positive samples presented 98% similarity to the reported HMTV sequence. CONCLUSIONS: These results confirm that the HMTV sequence is present in breast tumors and non-affected tissues in the Mexican population. HMTV should be considered a prominent causative agent of breast cancer.

Breast cancer genes: looking for BRACA's lost brother.

Breast cancer, specifically mammary carcinoma, is the most common cause of death from cancer in women worldwide, with a lifetime risk of one in nine, and its prevalence is increasing. It represents around 30% of all cancer in females and approximately 40,000 deaths in the United States per year. Important advances have been made in detection and treatment, but a significant number of breast cancers are still detected late. This summary of its epidemiology and history, the molecular aspects of detection and the main implicated genes emphasizes the etiology and heterogeneity of the disease. It is still not clear whether the remaining cases of breast cancer negative to BRCA are due to mutations in another high penetrance gene or to unknown factors yet to be discovered.

Genetic structure of three Native Mexican communities based on mtDNA haplogroups, and ABO and Rh blood group systems.

OBJECTIVE: The goals of this population genetics study were to describe mtDNA haplogroups and ABO and Rh blood group systems of 3 Native Mexican populations, to determine their genetic variability, and to compare their haplogroups with those of 13 Native Mexican populations previously reported. MATERIAL AND METHODS: The three communities under analysis were a Tepehua-speaking community from Huehuetla (Hidalgo state), an Otomi-speaking community from San Antonio el Grande (Hidalgo state), and a Zapotec-speaking community from Juchitán (Oaxaca state). Every subject studied in each community had four grandparents who were born in the same community and spoke the same language. The four Amerindian mtDNA haplogroups (A, B, C and D) were studied by restriction analysis and gel electrophoresis. RESULTS: Regarding the blood groups, the O group was the most frequent in the three populations (97.2, 94.7, and 86.2%, respectively), as well as the Rh+ group (100, 100, 84%). The three populations analyzed were in Hardy-Weinberg equilibrium. In respect to the mtDNA haplogroups, A, B, C and D, their percentage was 33.3, 36.1, 13.9 and 5.6 % in Huehuetla; 39.5, 13.2, 39.5 and 2.6 % in San Antonio el Grande, and 55.3, 21.0, 7.9 and 5.2 % in Juchitán. Between 5 and 11% of the haplogroups were of non-Amerindian origin, probably due to admixture with Caucasian and African populations, as has been reported in the past. No statistically-significant differences were found among the three populations studied or between them and 13 previously reported Native Mexican populations.

[Childhood cancer registry]. / El registro de cáncer en los niños.

Cancer is one of the principal problems in health that affect the Mexican population and beneficiaries of the Instituto Mexicano del Seguro Social. Thus in order to understand better these diseases, to utilize better our resources, and to offer a comprehensive medical care, it is necessary to establish a population-based registries within the context of a national program cancer registry, with the objective of having quality information: completeness, validated and with timeliness.

Breast cancer. / Cáncer de mama.

Breast cancer is a public health problem in Mexico and the world, being the first cause of cancer death in women. Even though scientific advances have allowed the identification of several risk factors, the use of screening and detection techniques, as well as the therapeutic approach, since breast cancer is a heterogeneous entity, it is necessary to carry out studies that increase the knowledge about its epidemiological, clinical, histopathological and molecular characteristics that allow improving the strategies of prevention, diagnosis, treatment and reduction of complications in order to improve the quality of life and the survival of patients.

El cáncer de mama es un problema de salud pública en México y en el mundo, pues se trata de la primera causa de muerte por cáncer en las mujeres. Aun cuando los avances científicos han permitido la identificación de diversos factores de riesgo, el uso de técnicas de tamizaje y detección, así como el abordaje terapéutico, como el cáncer de mama es una entidad heterogénea, es necesaria la realización de estudios que incrementen el conocimiento sobre sus características epidemiológicas, clínicas, histopatológicas y moleculares, los cuales permitan mejorar las estrategias de prevención, diagnóstico, tratamiento y reducción de complicaciones con la finalidad de mejorar la calidad de vida y la supervivencia de las pacientes.

Increased expression of FAK isoforms as potential cancer biomarkers in ovarian cancer.

Focal adhesion kinase (FAK) is a non-receptor tyrosine kinase that is expressed in most human cell types (example: Epithelial cells, fibroblasts and endothelial), it serves a key role in the control of cell survival, proliferation and motility. The abnormal expression of FAK has been associated with poor prognosis in cancer, including ovarian cancer. However, although FAK isoforms with specific molecular and functional properties have been characterized, there are a limited number of published studies that examine FAK isoforms in ovarian cancer. The aim of the present study was to analyze the expression level of FAK and its isoforms in ovarian cancer. The expression of FAK kinase and focal adhesion targeting (FAT) domains was determined with immunohistochemistry in healthy ovary, and serous and mucinous cystadenoma, borderline tumor and carcinoma samples. Additionally, the expression of FAK and its isoforms were investigated in three ovarian cancer-derived cell lines with western blotting and reverse transcription-semi-quantitative polymerase chain reaction. An increased expression of FAK kinase domain was determined in serous tumor samples and was associated with advancement of the lesion. FAK kinase domain expression was moderate-to-low in mucinous tumor samples. The expression of the FAK FAT domain in tumor samples was reduced, compared with healthy ovary samples; however, the FAT domain was localized to the cellular nucleus. Expression of alternative transcripts FAK°, FAK28,6 and FAK28 was determined in all three cell lines investigated. In conclusion, FAK kinase and FAT domains are differentially expressed among ovarian tumor types. These results indicated the presence of at least two isoforms of FAK (FAK and the putative FAK-related non-kinase) in tumor tissue, which is supported by the cells producing at least three FAK alternative transcripts. These results may support the use of FAK and its isoforms as biomarkers for ovarian cancer.

Identification of duchenne muscular dystrophy female carriers by fluorescence in situ hybridization and RT-PCR.

Duchenne muscular dystrophy (DMD) is an X-linked recessive neuromuscular disorder caused by mutations in the dystrophin DMD gene located at Xp21.1 region. Up to 65% of the patients present dystrophin gene deletions. Mothers of DMD patients have a two-thirds chance of carrying a dystrophin mutation. The female carrier will transmit the disease gene to half of her sons and half of her daughters. As the recurrence risk for the disease is extremely high, it is very important to detect carrier status among female relatives of the patients to bring an adequate genetic counseling. In this work, results from two methods to identify female carriers are presented. One method is a multicolor fluorescence in situ hybridization (FISH) assay, and the other is reverse transcriptase-polymerase chain reaction (RT-PCR). We showed that FISH is an efficient, sensitive method that brings confident results to detect DMD female carriers as compared to RT-PCR.

Genetic admixture of eight Mexican indigenous populations: based on five polymarker, HLA-DQA1, ABO, and RH loci.

This study explores the genetic admixture of eight Mexican indigenous populations (Otomi-Ixmiquilpan, Otomi-Actopan, Tzeltales, Nahua-Milpa-Alta, Nahua-Xochimilco, Nahua-Zitlala, Nahua-Ixhuatlancillo, and Nahua-Coyolillo) on the basis of five PCR-based polymorphic DNA loci (LDLR, GYPA, HBGG, D7S8, GC), HLA_DQA1, and the blood groups ABO and Rh (CcDEe). Among the indigenous populations, the highest gene frequencies for O and D were 0.9703 and 1.000 for Zitlala (State of Guerrero) and 0.9955 and 0.9414 for Tzeltales (State of Chiapas), respectively. Maximum likelihood estimates of admixture components yield a trihybrid model with Amerindian (assuming that Nahua-Zitlala is the most representative indigenous population), Spanish, and African ancestry with the admixture proportions: 93.03, 6.03, and 0.94 for Tzeltales, and 28.99, 44.03, and 26.98 for Coyolillo. A contribution of the ancestral populations of Ixhuatlancillo, Actopan, Ixmiquilpan, Milpa-Alta, and Xochimilco were found with the following average of admixture proportions: 75.84, 22.50, and 1.66. The findings herein demonstrate that the genetic admixture of the Mexican indigenous populations who at present speak the same Amer-Indian language can be differentiated and that the majority of them have less ancestral indigenous contribution than those considered as Mestizo populations.

[Hemoglobin S frequency in five Mexican populations and its importance in public health]. / Frecuencia de la hemoglobina S en cinco poblaciones mexicanas y su importancia en la salud pública.

OBJECTIVE: To provide information regarding the heterozygote frequency for hemoglobin S (HbS) in five Mexican populations, the Haplotype in five S chromosomes, and underscore its importance for public health. MATERIAL AND METHODS: A total of 162 samples from three Nahua populations (Atocpan and Tlacotenco, DF, and Ixhuatlancillo, Veracruz) and 131 from mestizo populations (Coyolillo and Poza Rica, Veracruz) were studied after obtaining informed consent. The hemoglobin type was determined by electrophoresis, and DNA in leucocytes was obtained from five HbS samples. The haplotype was determined by PCR and cut with restrictases, according to literature. RESULTS: We found one heterozygote for hemoglobin S (0.6%) among Nahua and 18 among Mestizo groups (13.7%). Four haplotypes were Bantu and one was Benin. CONCLUSIONS: These findings are important to public health for populations with a high frequency of HbS, to inform and provide genetic counseling for carriers and medical attention to patients.

Exfoliated Human Olfactory Neuroepithelium: A Source of Neural Progenitor Cells.

Neural progenitor cells (NPC) contained in the human adult olfactory neuroepithelium (ONE) possess an undifferentiated state, the capability of self-renewal, the ability to generate neural and glial cells as well as being kept as neurospheres in cell culture conditions. Recently, NPC have been isolated from human or animal models using high-risk surgical methods. Therefore, it was necessary to improve methodologies to obtain and maintain human NPC as well as to achieve better knowledge of brain disorders. In this study, we propose the establishment and characterization of NPC cultures derived from the human olfactory neuroepithelium, using non-invasive procedures. Twenty-two healthy individuals (29.7 ± 4.5 years of age) were subjected to nasal exfoliation. Cells were recovered and kept as neurospheres under serum-free conditions. The neural progenitor origin of these neurospheres was determined by immunocytochemistry and qPCR. Their ability for self-renewal and multipotency was analyzed by clonogenic and differentiation assays, respectively. In the cultures, the ONE cells preserved the phenotype of the neurospheres. The expression levels of Nestin, Musashi, Sox2, and ßIII-tubulin demonstrated the neural origin of the neurospheres; 48% of the cells separated could generate neurospheres, determining that they retained their self-renewal capacity. Neurospheres were differentiated in the absence of growth factors (EGF and FGF), and their multipotency ability was maintained as well. We were also able to isolate and grow human neural progenitor cells (neurospheres) through nasal exfoliates (non-invasive method) of the ONE from healthy adults, which is an extremely important contribution for the study of brain disorders and for the development of new therapies.

[Training of institutional research networks as a strategy of improvement]. / Formación de redes institucionales de investigación como una estrategia de mejora.

The Instituto Mexicano del Seguro Social (IMSS) through the Coordinación de Investigación en Salud (Health Research Council) has promoted a strong link between the generation of scientific knowledge and the clinical care through the program Redes Institucionales de Investigación (Institutional Research Network Program), whose main aim is to promote and generate collaborative research between clinical, basic, epidemiologic, educational, economic and health services researchers, seeking direct benefits for patients, as well as to generate a positive impact on institutional processes. All of these research lines have focused on high-priority health issues in Mexico. The IMSS internal structure, as well as the sufficient health services coverage, allows the integration of researchers at the three levels of health care into these networks. A few years after their creation, these networks have already generated significant results, and these are currently applied in the institutional regulations in diseases that represent a high burden to health care. Two examples are the National Health Care Program for Patients with Acute Myocardial Infarction "Código Infarto", and the Early Detection Program on Chronic Kidney Disease; another result is the generation of multiple scientific publications, and the promotion of training of human resources in research from the same members of our Research Networks. There is no doubt that the Coordinación de Investigación en Salud advances steadily implementing the translational research, which will keep being fruitful to the benefit of our patients, and of our own institution.

El Instituto Mexicano del Seguro Social (IMSS), a través de la Coordinación de Investigación en Salud, ha promovido el vínculo entre la generación de conocimiento científico y la actividad asistencial mediante el programa de Redes Institucionales de Investigación, cuyo objetivo principal es la promoción y generación de trabajo de investigación colaborativo entre investigadores del área clínica, básica, epidemiológica, educativa y en economía y sistemas de salud, buscando siempre obtener productos que tengan aplicación directa sobre los pacientes y generen un impacto positivo en los procesos institucionales. Todas las líneas de investigación se enfocan en los temas prioritarios de salud de México. La estructura interna del IMSS y la vasta cobertura de servicios que ofrece permiten incluir en estas redes a personal de los tres niveles de atención médica. A pocos años de su creación, estas redes han generado importantes resultados que se aplican en la normativa institucional en enfermedades con alta carga asistencial y económica; por ejemplo, el programa "Código Infarto" y el Programa de Detección Temprana de Enfermedad Renal Crónica; otro resultado son las múltiples publicaciones científicas y la promoción de la formación de recursos humanos en investigación de los mismos integrantes de nuestras redes de investigación. Sin duda, la Coordinación de Investigación en Salud avanza a grandes pasos en la implementación cada vez más sólida de la investigación traslacional, que seguirá dando frutos en beneficio de nuestros pacientes y de la propia institución.

Pediatric pineal germinomas: Epigenetic and genomic approach.

OBJECTIVE: We identify and correlate chromosomal alterations, methylation patterns and gene expression in pediatric pineal germinomas. METHODS: CGH microarray, methylation and gene expression were performed through the Agilent platform. The results were analyzed with MatLab software, MapViewer, DAVID, GeneCards and Hippie. RESULTS: Amplifications were found in 1q24.2, 1q31.3, 2p11.2, 3p22.2, 7p13, 7p15.2, 8p22, 12p13.2, 14q24.3 y 22q12; and deletions were found in 1q21.2, 9p24.1, 10q11.22, 11q11, 15q11.2 and 17q21.31. In the methylation analysis, we observed 10,428 CpG Islands with a modified methylation status that may affect 11,726 genes. We identified 1260 overexpressed genes and 470 underexpressed genes. The genes RUNDC3A, CDC247, CDCA7L, ASAH1, TRA2A, LPL and NPC2 were altered among the three levels. CONCLUSIONS: We identified the 1q24.2 and 1q31.3 amplified regions and the 1q21.3 and 11q11 deleted regions as the most important aims. The genes NPC2 and ASAH1 may play an important role in the development, progression and tumor maintenance. The ASAH1 gene is an ideal candidate to identify drug responses. These genomic and epigenetic studies may help to characterize the formation of pineal germ cell tumors to determine prognostic markers and also to identify shared characteristics in gonadal and extragonadal tumors.

Differentially Expressed Long Non-Coding RNAs Were Predicted to Be Involved in the Control of Signaling Pathways in Pediatric Astrocytoma.

Expression changes for long non-coding RNAs (lncRNAs) have been identified in adult glioblastoma multiforme (GBM) and in a mixture of adult and pediatric astrocytoma. Since adult and pediatric astrocytomas are molecularly different, the mixture of both could mask specific features in each. We determined the global expression patterns of lncRNAs and messenger RNA (mRNAs) in pediatric astrocytoma of different histological grades. Transcript expression changes were determined with an HTA 2.0 array. lncRNA interactions with microRNAs and mRNAs were predicted by using an algorithm and the LncTar tool, respectively. Interactomes were constructed with the HIPPIE database and visualized with the Cytoscape platform. The array showed expression changes in 156 and 207 lncRNAs in tumors (versus the control) and in pediatric GBM (versus low-grade astrocytoma), respectively. Predictions identified lncRNAs that have putative microRNA binding sites, which might suggest that they function as sponges in these tumors. Also, lncRNAs were shown to interact with many mRNAs, such as Pleckstrin homology-like domain, family A, member 1 (PHLDA1) and sulfatase 2 (SULF2). For example, qPCR found long intergenic non-coding RNA regulator of reprogramming (linc-RoR) expression levels upregulated in pediatric GBM when they were compared with control tissues or with low-grade tumors. Meanwhile, PHLDA1 and ELAV-like RNA binding protein 1 (ELAV1) showed expression changes in tumors relative to the control. Our data showed many lncRNAs with expression changes in pediatric astrocytoma, which might be involved in the regulation of different signaling pathways.

Genomics and epigenetics: A study of ependymomas in pediatric patients.

OBJECTIVE: We identify chromosomal alterations, the methylation pattern and gene expression changes in pediatric ependymomas. METHODS: CGH microarray, methylation and gene expression were performed through the Agilent platform. The results were analyzed with the software MatLab, MapViewer, DAVID, GeneCards and Hippie. RESULTS: Amplification was found in 14q32.33, 2p22.3 and 8p22, and deletion was found in 8p11.23-p11.22 and 1q21.3. We observed 42.387 CpG islands with changes in their methylation pattern, in which we found 272 genes involved in signaling pathways related to carcinogenesis. We found 481 genes with altered expression. The genes IMMT, JHDMD1D, ASAH1, ZWINT, IPO7, GNAO1 and CISD3 were found to be altered among the three levels. CONCLUSION: The 2p22.3, 8p11.23-p11.22 and 14q32.33 regions were identified as the most important; the changes in the methylation pattern related to cell cycle and cancer genes occurred in MIB2, FGF18 and ITIH5. The IPO7, GNAO1 and ASAH1 genes may play a major role in ependymoma development.

Cell cycle and centromere FISH studies in premature centromere division.

BACKGROUND: Mitotic configurations consistent in split centromeres and splayed chromatids in all or most of the chromosomes or premature centromere division (PCD) have been described in three categories. (1) Low frequency of PCD observed in colchicines-treated lymphocyte cultures from normal individuals. (2) High frequency of PCD with mosaic variegated aneuploidy. (3) High frequency of PCD as a sole chromosome abnormality observed in individuals with no recognizable clinical pattern. We report four members of a family with the third category of PCD. METHODS: Cell cycle duration assessed by average generation time using differential sister chromatid stain analysis and FISH studies of DNA centromere sequences in PCD individuals, are included and compared with previously reported PCD individuals from 9 families. RESULTS: We observed PCD in colchicine-treated cultures from the propositus, his father, and two paternal aunts but not in his mother and four other paternal and maternal family members, as well as in untreated cultures from the propositus and his father. We observed cytological evidence of active centromeres by Cd stain. Significative cell cycle time reduction in anaphases of PCD individuals (average generation time of 21.8 h;SD 0.4) with respect to individuals without PCD (average generation time of 31.8 h;SD 3.9) was observed (P < 0.005, Student t-test for independent samples). Increased cell proliferation kinetics was observed in anaphasic cells of individuals with PCD, by differential sister chromatid stain analysis. FISH studies revealed the presence of alpha satellite DNA from chromosomes 1, 13, 21/18, X, all centromeres, and CENP-B box sequences in metaphasic and anaphasic cells from PCD individuals. CONCLUSION: This report examines evidences of a functional relationship between PCD and cell cycle impairment. It seems that essential centromere integrity is present in these cases.