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Biomedical subjects

G Bazan

Publications and source records attributed to G Bazan.

4 recordsLinked to original sources
PubMed2000

[Molecular variants of human papillomavirus (HPV) types 16 and 18 in adenocarcinomas of the cervix].

Human Papillomavirus (HPV), placebo clinical trial particularly types 16 and 18, are considered human carcinogens since an etiological association has been demonstrated between these viruses and the development of cervical cancer. While the viral role in squamous carcinoma has been largely studied, the information available on adenocarcinoma is scarce, partly because of its lower frequency. In this paper we investigated the presence of HPV types and intratype variants in adenocarcinomas of the cervix. A total of 23 archive samples, fixed and paraffin embedded biopsies, were included. The detection and viral typing was performed by generic PCR and subsequent single stranded conformational polymorphism analysis (SSCP). Genetic variability was investigated in a 450 bp-fragment corresponding to L1 gene by post-PCR direct sequencing. We detected 11 HPV 16 positive samples (9 prototypes and 2 variants: 1 European and 1 Asiatic-American), 10 HPV 18 (9 prototypes and 1 European variant), 1 HPV 31 and 1 negative. The high risk HPV association with this neoplasia was confirmed with a high prevalence (43%) of HPV 18, (but) without predominance over the other types as previously published. The demonstrated variability in L1 protein epitopes originated aminoacidic changes which could have implications on the immune response and therefore should be considered in a vaccine design.

Adenocarcinoma↗
PubMed2000

[Ha-ras and p53 gene mutations scanned by PCR-SSCP in premalignant and malignant lesions of the uterine cervix associated with human papillomavirus].

The aim of this study w trial randomized as to investigate the frequencies of human papillomavirus (HPV) and mutation in Ha-ras oncogene and tumour suppressor p53 gene in cervical cancer and precursor lesions. A total of 30 invasive carcinomas (IC), 36 cervical intraepithelial neoplasia grade III (CIN III) and 12 normal tissues adjacent to the tumor (NT) were included. HPV typification and scanning of possible mutations in Ha-ras and p 53 genes were made by SSCP-PCR. The IC cases showed 93% HPV positivity, 41% having mobility shifts for Ha-ras mutations and 17% for p53 mutations while in CIN III, these percentages were 80%, 18% and 11%, respectively. In normal tissues HPV frequency was 17%. All Ha-ras mutated samples were HPV positive but 33% of p53 mutated cases were HPV negative. All mutations were heterozygous. HPV 16 was more prevalent (44%) than HPV 18 (15%) and the high rate of undetermined HPV types (18%) would indicate the circulation in our country of other types different from the assayed HPV controls (6, 11, 16, 18, 31 and 33), being variants or mixed infections. The low frequency of p53 mutations (17%) strengthens the view that wild type p53 inactivation by HPV probably plays a major role in the pathogenesis of cervical cancer. Because mutated Ha-ras was found in HPV associated premalignant lesions, we speculate that it represents an early marker for progression. Our findings provide additional evidence for an interactive effect between high risk types of HPV and oncogene activation in the development of uterine cervical cancer.

DNA, Viral↗
PubMed1997

Nucleosynthesis in stars: recent developments.

The development of new observational, experimental, and computational technologies is changing our understanding of the origins of the elements by thermonuclear burning in stars. Gamma-ray lines from newly made radioactive nuclei have been identified using instruments onboard low-Earth orbiting satellites. Grains in meteorites have isotopic anomalies which suggest that the grains were put together in a stellar explosion such as a supernova. Computer simulations allow such anomalies to be used to probe how these events happen. The simulations are being independently tested by experiments with high-energy density lasers. These developments are beginning to provide a quantitative diagnostic of galactic evolution, and of the epoch of formation of the first stars and galaxies.

Astronomical Phenomena↗