Study of the Huntington's disease IT-15 gene in different ethnic groups in Ecuador.

This study aims to establish the current state of the IT-15 (HTT) gene in different Ecuadorian ethnic groups and patients by determining CAG triplet repeats, compared with the ethnicity of individuals. A total of 412 individuals were studied using nested polymerase chain reaction and Sanger sequencing: 75 individuals were indigenous (Kichwas), 211 mestizos, and 65 Afro-Ecuadorians. We included 31 patients who were clinically diagnosed with Huntington's disease (HD) and relatives of the affected patients (n = 30). Moreover, we correlated the presence of HD in Ecuadorian patients with 46 genetic ancestry-informative insertion-deletion polymorphic markers. We found that 77.20% had <28 CAG repetitions, 18.80% had mutable alleles, 2.27% had incomplete penetrance, and 1.70% reflected >39 repetitions. The average of CAG repetitions was 24 ± 3 for indigenous people; 28 ± 2 for mestizos; and 24 ± 3.2 repetitions for the Afro-Ecuadorians. The ancestral component showed that the main ancestry corresponded to Native Americans (0.873) and European ascendants (0.145), Africans were less represented in the evaluated population (0.018). There was a significant difference between the number of CAG repeats in mestizos and indigenous people (P < .01), suggesting that the Ecuadorian mestizo population has a risk factor for the gene mutation.

Association of genetic variants of membrane receptors related to recognition and induction of immune response with Helicobacter pylori infection in Ecuadorian individuals.

Helicobacter pylori (Hp) has a worldwide distribution showing its higher prevalence of infection in developing countries. Toll-like receptors (TLRs) and C-type lectin receptors (CLRs) are proteins that recognize pathogen-associated molecular patterns (PAMPs) and initiate an innate immune response by promoting growth and differentiation of specialized hematopoietic cells for host defense. Gastric infections led by Hp induce a Th-1 cellular immune response, regulated mainly by the expression of IFN-γ. In this retrospective case-control study, we evaluated the TLR1 1805T/G, TLR2 2029C/T, TLR4 896A/G, CD209 -336A/G and IFNGR1 -56C/T polymorphisms and their relationship with susceptibility to Hp infection. TLR1 1805T/G showed statistical differences when the control (Hp-) and infected (Hp+) groups (P = 0.041*) were compared; the TLR1 1805G allele had a protective effect towards infection (OR = 0.1; 95% CI = 0.01-0.88, P = 0.033*). Similarly, the IFNGR1 -56C/T polymorphism showed statistical differences between Hp+ and Hp- (P = 0.018*), and the IFNGR1 -56TT genotype exhibited significant risk to Hp infection (OR = 2.9, 95% CI = 1.27-6.54, P = 0.018*). In conclusion, the pro-inflammatory TLR1 1805T and IFNGR1 -56T alleles are related with susceptibility to Hp infection in Ecuadorian individuals. The presence of these polymorphisms in individuals with chronic infection increases the risk of cellular damage and diminishes the cellular immune response efficiency towards colonizing agents.

Mesenchymal stem cells facilitate the derivation of human embryonic stem cells from cryopreserved poor-quality embryos.

BACKGROUND: Human embryonic stem cells (hESCs) have opened up a new area of research in biomedicine. The efficiency of hESC derivation from frozen poor-quality embryos is low and normally achieved by plating embryos on mouse or human foreskin feeders (HFFs). We attempted to optimize embryo survival and hESC derivation. METHODS: Three conditions were tested on frozen poor-quality embryos: (i) embryo treatment with the Rho-associated kinase (ROCK) inhibitor, Y-27632; (ii) use of human mesenchymal stem cells (hMSCs) as feeders; and (iii) laser drilling (LD) for inner cell mass (ICM) isolation. Two hundred and nineteen thawed embryos were randomly treated with (n = 110) or without (n = 109) 10 microM Y-27632. Surviving embryos that developed to blastocyst stage (n = 50) were randomly co-cultured on HFFs (n = 21) or hMSCs (n = 29). ICM isolation was either by whole-blastocyst culture (WBC) or WBC plus LD. RESULTS: Embryo survival was 52% higher with Y-27632. hMSCs appeared to facilitate ICM outgrowth and hESC derivation: three hESC lines were derived on hMSCs (10.3% efficiency) whereas no hESC line was derived on HFFs. ROCK inhibition and ICM isolation method did not affect hESC efficiency. The lines derived on hMSCs (AND-1, -2, -3) were characterized and showed typical hESC morphology, euploidy, surface marker and transcription factor expression and multilineage developmental potential. The hESC lines have been stable for over 38 passages on hMSCs. CONCLUSION: Our data suggest that Y-27632 increases post-thaw embryo survival and that hMSCs may facilitate the efficiency of hESC derivation from frozen poor-quality embryos.

Telomeric associations in cigarette smokers exposed to low levels of X-rays.

Telomeric association (TA), i.e. fusion of chromosomes by their telomeres, predisposes a cell to genetic instability. Because of this we investigated the effect of X-rays exposure and cigarette smoking on the frequency of TA in peripheral blood lymphocytes of exposed individuals, in order to determine if TA can be a chromosomal marker in populations exposed to these carcinogens and if there is an synergistic effect between both agents. We found that the exposed groups show a greater percentage of TA when compared with the control group (P<0.001). However, although the percentage of metaphases with TA in the group with combined exposure (12.6%) was greater than in the others exposed groups (P<0.05), this value was less than the sum of the two individual effects (15.1%). Our results suggest that probably there is not an additive or synergistic effect between X-rays and smoking, and that TA may be a useful cytogenetic marker for evaluating populations exposed to mutagens.

Alternative strategies for school violence prevention.

A number of programs with empirical evidence of effectiveness in addressing problems of aggression and disruption have emerged in schools.

The DeltaF508 mutation in Ecuador, South America.

There are few reports about the incidence of the DeltaF508 mutation in Latin American countries. We show the study of the DeltaF508 mutation and the seven most common "European" mutations in 10 Ecuadorian CF affecteds. The incidence of DeltaF508 mutation found was 25% and none of the other seven was detected in our population, which indicates that at least 60% of the mutations in the studied population are different from most common in Europe. Similar data have been reported in other Amerindian populations, therefore it is suggested that Cystic Fibrosis in Ecuador-and other Amerindian countries in Latin America-have a different ethiology than that of Caucasian populations.

Adolescent substance use: preliminary examinations of school and neighborhood context.

In considering the influences of microsystems on adolescent substance use, familial and peer contexts have received the most extensive attention in the research literature. School and neighborhood settings, however, are other developmental contexts that may exert specific influences on adolescent substance use. In many instances, school settings are organized to provide educational services to students who share similar educational abilities and behavioral repertoires. The resulting segregation of students into these settings may result in different school norms for substance use. Similarly, neighborhood resources, including models for substance use and drug sales involvement, may play an important role in adolescent substance use. We briefly review literature examining contextual influences on adolescent substance use, and present results from two preliminary studies examining the contribution of school and neighborhood context to adolescent substance use. In the first investigation, we examine the impact of familial, peer, and school contexts on adolescent substance use. Respondents were 283 students (ages 13 to 18) from regular and special education classrooms in six schools. Although peer and parental contexts were important predictors of substance use, school norms for drug use accounted for variance in adolescent use beyond that explained by peer and parental norms. Data from a second study of 114 adolescents (mean age = 15) examines neighborhood contributions to adolescent substance use. In this sample, neighborhood indices did not contribute to our understanding of adolescent substance use. Implications for prevention are presented.

Search for mutations of the hRAD54 gene in sporadic meningiomas with deletion at 1p32.

The hRAD54 gene is related to a family of genes involved in DNA recombination and repair and encodes a protein with DNA helicase activity. hRAD54 has been mapped to 1p32, a region frequently involved in deletions in a variety of tumor types, including atypical and anaplastic meningiomas. To determine whether alterations of hRAD54 are a common event in meningeal tumors, by means of polymerase chain reaction-single-stranded conformation analysis we examined 29 tumor samples characterized by 1p deletions for hRAD54 mutations. Although 18 tumors displayed allelic loss at the gene region (1p32) as determined by microsatellite marker analysis, the sole coding-sequence alteration detected corresponded to a T-->C transition, with no amino-acid change. The genotype distribution was 10.34% TT, 44.8% TC, and 44.8% CC, whereas in the normal controls it was 3.77% TT, 13.2% TC, and 83.01% CC, and most meningiomas with 1 p32 deletion retained allele C. Another polymorphism due to a T-->C change was evidenced at nt 3008, in the 3' untranslated region. This change was evidenced in all cases we sequenced. These results appear to exclude the involvement of the hRAD54 gene in the pathogenesis of the nontypical meningiomas, although a detrimental effect of the hRAD54 polymorphisms cannot be ruled out.

NF2 gene mutations and allelic status of 1p, 14q and 22q in sporadic meningiomas.

Formation of meningiomas and their progression to malignancy may be a multi-step process, implying accumulation of genetic mutations at specific loci. To determine the relationship between early NF2 gene inactivation and the molecular mechanisms that may contribute to meningioma tumor progression, we have performed deletion mapping analysis at chromosomes 1, 14 and 22 in a series of 81 sporadic meningiomas (54 grade I (typical), 25 grade II (atypical) and two grade III (anaplastic)), which were also studied for NF2 gene mutations. Single-strand conformational polymorphism analysis was used to identify 11 mutations in five of the eight exons of the NF2 gene studied. All 11 tumors displayed loss of heterozygosity (LOH) for chromosome 22 markers; this anomaly was also detected in 33 additional tumors. Twenty-nine and 23 cases were characterized by LOH at 1p and 14q, respectively, mostly corresponding to aggressive tumors that also generally displayed LOH 22. All three alterations were detected in association in seven grade II and two grade III meningiomas, corroborating the hypothesis that the formation of aggressive meningiomas follows a multi-step tumor progression model.

Allelic status of 1p, 14q, and 22q and NF2 gene mutations in sporadic schwannomas.

Schwannomas are common benign tumours of schwann cell origin, frequently found in patients with neurofibromatosis type 2 (NF2). Inactivation of the NF2 tumour suppressor gene appears to be a molecular event responsible for the development of up to 60% of cases, but no data are available on other superimposed secondary or alternative molecular abnormalities in those schwannomas lacking NF2 gene inactivation. We analysed 23 sporadic schwannomas for mutations in the NF2 gene and for the allelic status at 1p, 14q and 22q, as alterations of these genomic regions appear to be related to tumour progression in meningiomas, another NF2-associated neoplasm. Nine samples displayed allelic losses for markers on chromosome 22, and deletions at 1p were detected in two. No case showed losses for 14q. Three tumours displayed NF2 gene mutations, at exons 2, 7 and 12. Our results confirm that inactivation of the NF2 gene is a primary event in schwannoma development, and provide data suggesting that allelic loss at 1p may contribute to the pathogenesis of a small subgroup of this histological tumour type.

Six novel mutations in the NF2 tumor suppressor gene.

Six novel mutations were identified in the NF2 tumor suppressor gene in a panel of meningiomas and neurinomas. Screening was performed using a combination of single-strand conformation polymorphism and heteroduplex analyses on polymerase chain reaction-amplified DNA from tumors and matched peripheral blood lymphocytes. Mutations involved exons 2, 7, 11 and 12, and corresponded to three frameshift, one nonsense, one missense and one polymorphism.

Telomeric association in women with breast and uterine cervix cancer.

This study compares the frequency of telomeric associations in the peripheral blood of women suffering breast and cervix uterine cancer with a healthy control group. Two kinds of cultures were developed for each individual: with and without aphidicolin. In the normal cultures, the number of telomeric associations observed was 95.5 times higher in individuals affected by breast cancer and 41.3 times higher in those affected by cervix uterine cancer when compared to the control group (p < 0.001). In the cultures with aphidicolin, higher numbers of altered metaphases were observed in both groups as compared to the control groups (p < 0.001). Statistically significant differences (p < 0.001) could also be observed when comparing telomeric associations between the two types of cancer in both cultures. When we compared individuals affected by breast cancer in both types of cultures statistical differences were found (p < 0.05), and similar results were found in individuals affected by uterine cervix cancer (p < 0.001). The findings suggest that telomeric associations may be reflecting chromosome instability observed in cancer and that this instability behaves differently for various types of cancer.

Comparative study of chromosome aberrations induced with aphidicolin in women affected by breast cancer and cervix uterine cancer.

Blood samples were obtained from 80 women: Twenty of these samples were from women affected by ductal infiltrating breast carcinoma, twenty from women affected by cervix uterine cancer, and forty individuals were screened for a control group. The search for chromosome instability that is known to affect individuals with cancer was performed through chromosome analysis in nontumor cells, intending to establish frequency and different types of numerical and structural aberrations. The results, in regard to spontaneous and aphidicolin induced chromosome aberrations, showed a significantly greater frequency (p < 0.001) of chromosome fragility, as well as other numerical and structural aberrations in breast cancer patients when compared to the control group. Similar results were obtained from cervix uterine cancer patients with the exception of certain numerical aberrations in which no significant differences were found. This suggests the existence of a certain degree of chromosomal instability affecting individuals with both types of cancer. The increase in fragility may play an important role in the biologic behavior and progression of cancer.

Follow up study of chromosome aberrations in lymphocytes in hospital workers occupationally exposed to low levels of ionizing radiation.

In the present study we analyzed and followed up on the cytogenetic effects of low levels of ionizing X-radiation on hospital workers at 72 h cultures. Samples of peripheral blood were collected from 10 hospital workers exposed to 1.84 mSv/year, and from 10 non exposed individuals, who were screened simultaneously and used as controls. The chromosomes were prepared using standard techniques. After 12 months, we undertook a second evaluation, this time with exposure to the same workers of 1.67 mSv/year. We observed 100 metaphases per subject, and there was a high percentage of altered metaphases (29.2% in the first sample and 26% in the second samples) The chromosome analysis in the second mitotic division, show aberrations such as gaps, breaks and acentric fragments, as well as other alterations such as dicentrics and rings, as well as chromosome variants (double minutes) in the exposed workers vs. the controls, and the difference was statistically highly significant (p < 0.001). There is no statistically significant difference between the first sample of exposed workers with the second one (p > 0.05). The findings in this study are interesting, because the workers were exposed to doses well below the accepted standards for exposure to radiations. Because of these unusual findings, our results could have potentially major consequences on our views on standards of exposure to radiation.

Allelic status of chromosome 1 in neoplasms of the nervous system.

By using five highly polymorphic markers, the allelic status of chromosome 1 was established in a series of 236 tumors of the nervous system, including all major histologic subtypes: gliomas, meningiomas, neurinomas, neuroblastomas, medulloblastomas, etc. Loss of alleles at 1p was observed at significant frequencies in neuroblastomas (26% of cases), meningiomas (32%), and malignant gliomas (37%) (primarily oligodendrogliomas [94%]). This anomaly was also detected in two of 23 neurinomas, two of three neurofibrosarcomas, one primary lymphoma, and two metastatic tumors of the brain. The analysis of tumors displaying partial 1p deletions suggests the existence of two distinct regions, 1p36 and 1p35-p32, in which loci nonrandomly involved in the development of neurogenic neoplasms might be located.

Allelic loss at 1p and 19q frequently occurs in association and may represent early oncogenic events in oligodendroglial tumors.

The molecular mechanisms underlying the genesis and progression of oligodendroglial tumors are poorly understood, since only restricted information on loss of heterozygosity from isolated cases is available. The commonest alterations appear to involve deletion of 1p and 19q, while loss of heterozygosity for 9p, chromosome 10 or epidermal growth factor receptor gene amplification have been described in single tumors. We have applied restriction fragment length polymorphism analysis to 14 loci covering chromosome 1 and 7 loci on chromosome 19 in a series of 25 tumors with an oligodendroglial component to determine precisely the participation of these suppressor genes in the genesis of tumors. Twenty-two and 19 of the 25 samples displayed LOH at 1p and 19q, respectively, and both anomalies were detected in association in 17 samples, including low- and high-grade oligodendrogliomas as well as mixed oligo-astrocytomas. Our findings suggest that inactivation of tumor suppressor genes located on 1p and 19q represent cooperative alterations occurring at early stages of oncogenic transformation of oligodendroglial neoplasms.

The perceived environment of special education classrooms for adolescents: a revision of the classroom environment scale.

The Classroom Environment Scale (CES), originally developed for use in traditional public school classrooms, was revised for use in special education classrooms. The scale, which assesses students' perceptions of various aspects of the classroom, was administered to students in 79 special education classrooms in 16 residential and day treatment schools serving special education students with behavior disorders and emotional disturbance. Psychometric analyses showed that only seven of the nine aspects of the classroom found in the original CES were reliably reported in special education classrooms. The revised scale was found reliable for use in special education classes in residential and day treatment settings.