Early modification of c-myc, Ha-ras and p53 expressions by chemical carcinogens (DMBA, MNU).

7,12-Dimethylbenz[a]anthracene (DMBA) and N-methyl-N-nitrosourea (MNU) are important environmental carcinogens. Their different biological effects were examined in CBA/Ca H-2(K) haplotype inbred mice on the gene expression of c-myc, Ha-ras and p53 through a 24 hour period. Elevated expression of c-myc and Ha-ras genes was found in the spleen, lung, thymus and lymph nodes 6 and 12 hours after DMBA treatment and in the lung and thymus 3 hours after MNU treatment. In the liver, DMBA induced strong onco/suppressor gene expression as early as 6 hours after the treatment, but MNU increased the p53 gene expression 12 hours after the treatment. The gene expression patterns reflected the different mechanism of the direct acting MNU and metabolically activated DMBA. This phenomenon provides evidence as to the usefulness of detection of onco/supressor key gene expression as early molecular epidemiological biomarkers of carcinogenesis and carcinogenic exposure in animal model, useful in human cancer prevention practice as well.

[Eigenfactor: a recent opportunity of measuring scientific journals]. / Az Eigenfaktor: a tudományos folyóiratok értékelésének újabb lehetosége.

There are various measures of a scientific journal's impact or relevance. Probably the best known measures based on citations are the impact factor published by Thomson Scientific, and the Hirsch-index created by Andras Schubert. Citations have long been an important way to evaluate the interest, visibility and impact of research, and the corresponding researchers. These ranks are very important for the researchers when deciding where to submit their manuscripts. Recently, Carl Bergstrom has suggested a new indicator called Eigenfactor. Eigenfactor ranks journals much as Google ranks websites. All sources consulted by the researcher during the research process contribute to the determination of the Eigenfactor. Is it possible that Eigenfactor will have the leading role in scientometry starting in the next century?

Early modification of c-myc, Ha-ras and p53 expressions by N-methyl-N-nitrosourea.

Methylnitrosourea (MNU) is a well-known pluripotent direct-acting carcinogen. Formation of MNU following incubation of various meats with additional nitrite under in vitro acidic conditions is possible. It is possible that many species, including humans, are exposed to carcinogenic MNU, generated in their alimentary tract. Previously, an animal model was developed by our research group to investigate the expression of three genes c-myc, Ha-ras and p53 as early molecular epidemiological biomarkers of carcinogenic exposure or carcinogenesis caused by DMBA (dimethylbenz[alpha]anthracene). The aim of this study was to investigate the early effect of MNU on the gene expression levels. MNU is a direct-acting carcinogen which spontaneously and rapidly degrades, so any effect on the gene expression is observed in 24 hours. Our results show the maximum effect in vivo on the gene expression at 12 hours after the MNU treatment; on the other hand, 24 hours after the treatment, the elevated gene expressions decreased in target organs (bone marrow, lung, lymph nodes). Our results correspond to "long-term" experiments of the carcinogenic effect of MNU in different target organs. Our findings suggest that MNU has an impact on the expression of c-myc, Ha-ras and p53 genes in 12 hours, especially in bone marrow. Overexpression of these genes occurs as an early biological effect of exposure to chemical carcinogens. According to our results, the high expression of these genes could indicate MNU exposure and these genes could take part in MNU-induced tumorigenesis.

[Impact factor and/or Hirsch index?]. / Impakt faktor és/vagy Hirsch-index?

Is the best measure of a scientist's worth the total number of his or her published papers? For many years Institute for Scientific Information has been publishing the lists of impact factors providing quantitative tools for ranking scientists. The impact factor was devised by Eugene Garfield, the founder of the Institute for Scientific Information. Impact factors are calculated each year by the Institute for Scientific Information for those journals which it indexes, and are published in Journal Citation Reports. These measures apply only to journals, not individual articles or individual scientists. For the impact factor of individual scientists, there exists the h-index or Hirsch number. The Hirsch-index (h-index) has recently been defined by Hirsch as a new method for measuring the scientific activity. If a scientist has published n articles which all have been cited at least n times, then he will have a h-index of n . The h-index seeks to describe the impact of individual researchers, rather than journals. The h-index is the result of the balance between the number of publications and the number of citations per publication. H-index: Impact of Individual Scientists. H-index or/and impact factor - it is the question of the future.