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Biomedical subjects

A Pestaña

Publications and source records attributed to A Pestaña.

At least 19 recordsLinked to original sources
PubMed1997

[Suitability of MEDLINE for the study of the Spanish scientific production in biomedicine and medical sciences. A comparative appraisal with the Science Citation Index].

BACKGROUND: MedLine (ML) database in CD-ROM, one of the most popular sources for bibliographic citations and abstracts of medical-biomedical literature, is also being widely used as a bibliometric tool. The usefulness of MedLine for bibliometric purposes needs to be evaluated. MATERIAL AND METHODS: A database (BDML) of the Spanish publications in medical-biomedical journals has been derived from ML in the period 1990-1994 searching for SPAIN or ESPANA in the author address (AD) and/or in the country of publication (CP) fields. Retrieved documents correspond to original and review articles. The journals were assigned to SCI categories and impact factors according to the Journal Citation Reports (1990 and 1994 issues). BDML contents were compared with the documents indexed in SCI-SSCI databases (1990-1993) as reported (Camí J et al. Med Clin [Barc] 1997; 109: 481-496). RESULTS: Spanish production in medical and biomedical publications indexed in BDML amounts to 27,452 documents in 1,639 journals or 19,915 documents in the 1,339 journals listed in JCR. This represents 3,983 articles and reviews in SCI journals per year on average. Similar calculation for the Spanish articles and reviews indexed in SCI-SSCI databases (1990-93) gives a rate of 3,727 documents/year. Coverage of biomedical literature in ML is much lower than in SCI + SSCI (11,729 and 15,723 documents respectively) although the differences can be lowered taking into account that SCI documents include case reports and letters to the Editor which can not be retrieved from ML searchs in the AD field. On the contrary, more Spanish articles in medical disciplines were retrieved from ML (15,723) than SCI + SSCI databases (7,858). ML indexes more Spanish medical journals than SCI (36 journals and 11,400 articles in ML90-94 against 12 journals and 1,622 documents in SCI90-93). CONCLUSIONS: The results validate the usefulness of MedLine for bibliometric studies in medical sciences.

Databases, Bibliographic↗
PubMed1997

Mutational analysis of the p16 gene in human neuroblastomas.

Neuroblastoma is one of the most frequent tumors in infancy. We analyzed 26 neuroblastomas, two ganglioneuromas, and a neuroblastoma metastasis for mutations and homozygous deletions of the p16 (or MTS1 or CDKN2) gene by means of the polymerase chain reaction (PCR) in combination with the single-strand conformation polymorphism (SSCP) technique and by multiplex PCR analysis. We detected mobility shifts in the SSCP gels in seven cases in the 3 half of exon 2 (named exon 2C) of the p16 gene. By PCR amplification of this particular region and SacII restriction enzyme digestion, we confirmed that those cases had a known polymorphism at codon 140 of the p16 gene. Neither mutations nor homozygous deletions were detected. Our results confirm those of Beltinger et al. (Cancer Res 55:2053-2055, 1995), which showed no p16 mutations or homozygous deletions in 18 primary neuroblastomas and nine tumor-derived cell lines. We conclude that the common pattern of p16 inactivation by homozygous deletion or mutation does not seem to be relevant to the development of neuroblastomas.

Carrier Proteins↗
PubMed1996

Chromosome 17 allelic loss and NF1-GRD mutations do not play a significant role as molecular mechanisms leading to melanoma tumorigenesis.

Allelic loss in human cutaneous melanoma has been detected on chromosomes 1p, 6q, 9p, 10q, and 11q. Chromosome 17 contains important tumor suppressor genes such as p53, NM23, and neurofibromatosis type 1 (NF1), which have been implicated in melanoma tumorigenesis. The role of p53 has already been studied by a number of laboratories, showing contrasting results. In the present study, two restriction fragment length polymorphism (RFLP) probes for the NM23 and NF1 genes, together with five other RFLP and four variable number of tandem repeat chromosome 17 probes, were investigated at the loss of heterozygosity (LOH) level in a Southern blot-based assay. The NF1 gene was also tested for LOH by a polymerase chain reaction (PCR)-based approach in two different experiments, using a dinucleotide repeat polymorphic probe at locus D17S250 (17q11.2-q12), and an Alu probe intragenic to the NF1 gene (17q11.2). A PCR single-strand conformation polymorphism assay was included in the study for mutation detection at the NF1-GTPase-activating protein-related domain (GRD). A total of 68 melanocytic tumors were analyzed. LOH was detected in 9 of 87 informative cases (10%). LEW301 (17p11.2-pcen) presented the highest LOH frequency (22%). NM23 showed LOH in 17% of the informative cases, while NF1 did not show either LOH in the Southern blot- and PCR-based experiments or mutations at the NF1-GRD. These results are in concordance with those of previous smaller studies, but when compared with higher LOH frequencies obtained from other chromosomes, these findings indicate that the LOH values found in our study can most likely be attributed to background effect. Thus, chromosome 17 LOH is likely to play and unimportant role as a genetic event in melanoma tumorigenesis. Nevertheless, NF1 merits further study, since homozygous deletions have been detected at this locus in melanoma cell lines.

Alleles↗
PubMed1995

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.

Chromosome Deletion↗
PubMed1995

Absence of mutation at the GAP-related domain of the neurofibromatosis type 1 gene in sporadic neurofibrosarcomas and other bone and soft tissue sarcomas.

The NF1 gene encodes neurofibromin, a GTPase-activating protein containing a GAP-related domain (NF1-GRD) that is capable of downregulating ras by stimulating ras intrinsic GTPase activity. We tested 44 sarcomas, nine of which corresponded to sporadic neurofibrosarcomas, for mutations at the NF1-GRD by the polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) technique, finding no mutation in every sample tested. We suggest that inactivation of the NF1-GRD by gene mutation seems not to be an important event in the tumorigenesis of sarcomas.

Bone Neoplasms↗
PubMed1995

[Sensibility and specificity of N-myc oncogene with respect to other prognostic factors in 15 neuroblastomas].

Several biologic features of tumor cells correlate closely with a favorable or unfavorable outcome. To aid in assessing correlation in the various number of prognostic factors including the age, stage, VMA/HVA ratios, and the serum levels of NSE and ferritin, the histopathological features, ploidy, partial monosomy for the short arm of chromosome 1, and the tumor N-myc gene copy number, are examined. We determined the sensitivity and specificity of classical markers above the amplification of the N-myc oncogene. A striking new observation is the positive correlation between genomic amplification and some prognostic factors (stage, ferritin, NSE, pathologic anatomy and 1p deletion.

Brain↗
PubMed1994

Life class.

Explore the source record for details and available documents.

Abortion, Induced↗
PubMed1994

Molecular and cytogenetic analysis of chromosome 9 deletions in 75 malignant gliomas.

A deletion mapping analysis of chromosome 9 has been performed on a series of 75 samples derived from malignant gliomas. A total of 27 tumors displayed different deletions for the loci studied (D9S1, NRASLI, D9S18, IFNA, and IFNBI). In most instances, losses involving the markers located on the short arm of chromosome 9 were observed, and only two samples were characterized by losses of the short and long arms. Either partial or complete homozygous deletions of IFN genes were observed in 15 cases, and 12 other samples showed hemizygous deletions for these genes. The results show that the 9p abnormalities are not exclusive to high-grade astrocytic tumors, as some low-grade samples (two astrocytoma grade II and six oligodendrogliomas) displayed this anomaly which, in a few instances, was the sole abnormality detected.

Chromosome Deletion↗
PubMed1994

Allelic loss at 1p is associated with tumor progression of meningiomas.

Next to chromosome 22 anomalies, deletions of the short arm of chromosome 1 have previously been described as the most frequent alteration detected by cytogenetic analysis of meningiomas. To determine the incidence of these deletions, we have analyzed a series of 50 meningiomas for the loss of alleles at four chromosome 1 loci. Thirteen samples displayed LOH for the markers studied; in one instance, the results were compatible with loss of the entire chromosome 1, whereas in the other 12 samples deletions of the short arm were observed. Eleven of the meningiomas had previously been shown to have loss of alleles on chromosome 22, and 12 of them were characterized by increased tumor aggressiveness. These findings suggest that deletion of Ip (or the alteration of a locus located there) might represent a secondary, but nonrandom alteration in meningiomas, perhaps contributing to meningioma tumor progression.

Alleles↗
PubMed1994

No TP53 mutations in neuroblastomas detected by PCR-SSCP analysis.

We have analysed 29 neuroblastomas for TP53 mutations in exons 5 to 8 by means of the polymerase chain reaction in combination with the single-strand conformation polymorphism technique. We could not detect any mutation. These results indicate that, in contrast to the majority of tumors so far studied, TP53 mutations do not seem to be important for the development of neuroblastomas.

DNA, Neoplasm↗
PubMed1994

Molecular analysis of genomic abnormalities in human gliomas.

A series of 57 malignant gliomas, including 27 astrocytomas grade III-IV (glioblastoma multiforme), 15 astrocytomas grade I-II, and 15 tumors with major oligodendroglial component, was examined to detect molecular abnormalities of loci at specific chromosome regions. At the cytogenetic level, these regions have been shown to be nonrandomly involved in neoplastic development of these histologic subtypes of tumor. We used a panel of 24 polymorphic DNA probes to analyze loss of heterozygosity (LOH) at loci on chromosomes 7, 9, 10, 13, 17p, and 22q. In addition, the retinoblastoma (RB1) oncosuppressor gene, the platelet-derived growth factor A (PDGFA) gene, and the epidermal growth factor receptor (EGFR) gene were analyzed directly. Loss of genetic information on the short arm of chromosome 17 was observed in both low- and high-grade astrocytomas, whereas no oligodendroglial tumor was characterized by this type of aberration. LOH for chromosome 10, mainly compatible with loss of the entire chromosome, was primarily evidenced in the more malignant forms and in isolated cases diagnosed as low-grade astrocytomas. Again, no oligodendroglial tumor displayed losses of chromosome 10. In contrast, four tumors with major oligodendroglial component showed losses involving 9p markers, primarily interferon A and B (IFNA, IFNB); this feature was also observed in two low-grade astrocytomas and in 11 high-grade tumors. Isolated cases displayed LOH for markers on chromosomes 13 and 22, whereas EGFR amplification was almost exclusively evidenced in the more malignant forms which, in most instances, also presented LOH for chromosome 10. In general, the samples with lower malignancy stage displayed a lesser grade of abnormalities, mainly restricted to losses at 17p and chromosome 10 in astrocytomas grade I-II and at 9p in oligodendrogliomas. In contrast, about 50% of the high-grade tumor samples analyzed included abnormalities at two or more loci, with a recurrent association of EGFR amplification and LOH for chromosome 10; this association was evident in 26% of the high-grade astrocytomas.

Adult↗
PubMed1993

Clonal chromosome aberrations in neurinomas.

Chromosome studies were performed after short-term in vitro culture of 39 samples from neurinomas and two samples from malignant schwannomas. Clonal abnormalities involving chromosome 22 were observed in 23 cases, as the sole chromosomal deviation in 12 of them. In 11 samples, other clonal numerical and/or structural aberrations were detected in addition to loss of chromosome 22, either in the same cells or in cells other than those having monosomy 22. Within the group of neurinomas with no involvement of chromosome 22, there were again two cytogenetically distinctive subgroups: one with an abnormal karyotype, and the second with a normal chromosome complement. Our findings confirm that monosomy 22 is a characteristic feature of this type of neoplasm, but also suggest the existence of different cytogenetic subgroups of neurinomas.

Chromosome Aberrations↗
PubMed1993

Abnormalities of chromosome 22 in human brain tumors determined by combined cytogenetic and molecular genetic approaches.

Southern blot hybridization studies were performed on a panel of 130 blood/tumor samples from brain neoplasms including all major histologic subtypes: 50 meningiomas, 18 neurinomas, 56 gliomas, and six others. To detect abnormalities involving chromosome 22, polymorphic probes were used to analyze eight loci located in this chromosome: D22S9, IGLV, D22S20, D22S32, MB, PDGF-B, D22S80, and D22S171. Loss of heterozygosity (LOH) was observed in 40 cases including monosomy, terminal, and interstitial deletions, which suggest the location of recessive tumor genes in certain chromosome 22 subregions (22q11.3-q12 in neurinomas and meningiomas, and 22q13 in malignant gliomas). Cytogenetic studies were performed in parallel on the same tumors, in most instances corroborating the presence of abnormalities for chromosome 22. Nevertheless, discrepancies between the cytogenetic and molecular findings were observed in several cases, suggesting that the use of both methodologies in combination might provide key information on the incidence and extent of the abnormalities involving chromosome 22 in human brain tumors.

Blotting, Southern↗
PubMed1993

Involvement of 22q12 in a neurofibrosarcoma in neurofibromatosis type 1.

We describe the cytogenetic and molecular genetic findings in a neurofibrosarcoma arising in a patient affected by neurofibromatosis type 1. Multiple chromosomal rearrangements were found but only a few of them were identified as clonal abnormalities, including a deletion of chromosome 22, which at the molecular level proved to be interstitial, mainly involving the 22q12 region. Loss of heterozygosity for markers D22S32 and MB was observed. These findings are in agreement with previous data which suggest a possible involvement of a gene located at 22q11-q13.1 during the neoplastic development of some neurofibromatosis type 1-associated tumors.

Adult↗
PubMed1993

Chromosome 22 heterozygosity is retained in most hyperdiploid and pseudodiploid meningiomas.

Hyperdiploid or pseudodiploid modal chromosome numbers were found characterizing six human meningiomas, and all six tumors were disomic for chromosome 22. The scarce previous reports on the subject suggest that, in these cytogenetic subgroups of meningiomas, duplication of the retained chromosome 22 occurs after the loss of the other member of the pair, thus correlating well with the main characteristic of meningiomas, that is, losses of 22. To verify this question, molecular genetic analyses were performed on DNA pairs from blood and tumoral samples of all six cases, using polymorphic markers for chromosome 22. Restriction fragment length polymorphism studies failed to show any loss of heterozygosity for markers located on this chromosome in all six cases, suggesting that a different mechanism to that previously proposed might take place in the hyperdiploid or pseudodiploid meningiomas; perhaps a submicroscopic involvement (microdeletions or inactivating mutations) of the meningioma locus (both alleles) may result in an effect similar to that produced by monosomy 22 (which probably unmasks recessive mutations on the retained allele), enhancing the development of meningiomas.

Alleles↗