1,721,061 research outputs found
Aphidicolin does not inhibit the repair synthesis of mitotic chromosomes.
No full textAphidicolin does not inhibit the repair synthesis of mitotic chromosomes
Gene amplification, radiation sensitivity and DNA double-strand breaks
No full textDNA double-strand breaks (DSBs) are one of the main types of damage induced by ionizing radiations. Free DNA ends that are not correctly repaired can be engaged in pathways triggering gene amplification. Following gene amplification the copy number of a portion of the genome is increased, leading to an enhanced expression of the genes located in the amplified region. Gene amplification plays an important role in cancer, being one of the mechanisms of oncogene activation; in addition, it can confer resistance to chemotherapeutic agents, through the increase in the copy number of genes coding for drug targets. The presence of gene amplification can have a prognostic and a diagnostic value and can help in orienting therapy in specific tumour types. The amplified DNA is primarily produced through recombination-based pathways and can be located either within chromosomes or on extra-chromosomal acentric elements. Studies on the organization of the amplified DNA in tumour cells and in cultured drug resistant cells have suggested that a single DSB can trigger a cascade of events leading to a large number of copies of a region of the genome. In addition, it has been shown that amplified DNA is unstable, further increasing the long-term effect of the initial event. Gene amplification is a peculiar feature of transformed cells and the ability to amplify is strongly influenced by the cellular genetic background. Genes involved in DNA damage response and in DNA damage repair can play a role in controlling the amplification process, in particular, it has been shown that defects in DSB repair functions can increase the frequency of gene amplification. In this review, we will discuss the biological significance of gene amplification, together with the role of DNA DSBs and DSB repair genes in the generation of amplified DNA
La vasectomia a sostegno del piacere: analisi casistica e considerazioni medico legali
No full textIn Italy, the resort to vasectomy, surgery adapted to determine an irreversible alteration of the physical state of an individual, resulting in the loss of the ability to procreate, is somewhat reduced compared to the others European countries, even though legitimate, it carries the disadvantage of the absence of a clear and univocal legislation concerning surgical sterilization. Despite, in recent years there has been a change in the assessment of such surgery. Nevertheless, is relevant that in the Italian legal system still lacks a regulatory of such medical-surgery activities, although several bills have been submitted to the competent parliamentary bodies. The attitude of indifference to the problem is also evident from the analysis of the provisions relating to assistance by the SSN, even if the vasectomy and the voluntary sterilization have been included in the reimbursable procedure’s list. On the basis of these assumptions the authors report - for the peculiarity of the case and that the issue is of interest in forensic discipline - a case came to their attention, and the data from medical records relating to the 64 requests of vasectomy received during the period of between January 2000 and October 2011 in a hospital in Lombardy, highlighting strengths and weaknesses of the existing protocol in use at that hospital: in addition, there are deficiencies in the informed consent form
Killing methods in Sicilian Mafia families
No full textThe Sicilian Mafia is a criminal organisation founded in Sicily which is an island south of the Italian mainland in the Mediterranean Sea. Until recently, this organization was responsible for many murders and bombings. However, recently, based on the investigations known as the "Mare Nostrum" operation, the Supreme Court convicted 67 people and sent them to prison. Some defendants were found guilty of as many as 39 murders. This article reviews the forensic analysis that was used when investigating responsibility for these Mafia murders. Our review is based on the court documents and the ballistic investigations which were carried out to evaluate the reliability of "repented" or "pentiti" statements. The murder victims were almost all men but one was a woman all of whom had gunshot lesions; in many cases, the fatal injuries were to the head and face. Ballistic analysis showed that in more than half of these murders, more than one weapon was used. In conclusion, the forensic analysis of the murders shows the Sicilian inter-families' dynamics and their characteristic operating methods
Chromosomal end-to-end fusions in immortalized mouse embryonic fibroblasts deficient in the DNA-dependent protein kinase catalytic subunit
No full textTelomeres constitute the ends of the linear eukaryotic chromosomes and are essential for the maintenance of chromosome stability and genome integrity. One of the consequences of an altered telomere structure is the formation of telomeric fusions (TFs), that is aberrant chromosomes in which two elements are fused at their telomeres. Proteins involved in the non-homologous end joining pathway for the repair of the DNA double strand breaks, as the DNA-dependent protein kinase catalytic subunit (DNA-PKcs), contribute to the formation of a functional telomere. To investigate the role of DNA-PKcs in telomere functionality, we studied the frequency of TFs in mouse embryonic fibroblasts obtained from animals in which the DNA-PKcs gene had been inactivated; the analysis was performed prior and after spontaneous immortalization in culture. Our results suggest that DNA-PKcs deficiency has a limited effect, if any, on TF formation in primary cells, while it further increases chromosomal instability in immortalized cells. In fact, the frequency of TFs was significantly higher in immortalized DNA-PKcs mutant cells compared to wild type cells. Together with TFs, we also found metacentric or submetacentric chromosomes in which no telomeric sequences were detected at the joining site. The frequency of this anomaly, that resembles the Robertsonian translocations observed in wild mice, was independent of the DNA-PKcs genotype. This suggests that the formation of these rearranged chromosomes does not rely on a functional DNA-PKcs
Gamma-ray and hydrogen peroxide induction of gene amplification in hamster cells deficient in DNA double strand break repair
No full textTo investigate the role of DNA double strand breaks (DSBs) and of their repair in gene amplification, we analyzed this process in the V3 Chinese hamster cell line and in the parental line AA8, after exposure to gamma-rays and to hydrogen peroxide (H2O2). V3 is defective in DSB repair because of a mutation in the DNA-dependent protein kinase catalytic subunit (DNA-PKcs) gene, a gene involved in the non-homologous end-joining pathway. As a measure of gene amplification we used the frequency of colonies resistant to N-(phosphonacetyl)-L-aspartate (PALA), since in rodent cells PALA resistance is mainly achieved through the amplification of the CAD (carbamyl-P-synthetase, aspartate transcarbamylase, dihydro-orotase) gene. After treatment with different doses of gamma-rays and of H2O2, we found a dose related increase in the frequency of gene amplification and of chromosome aberrations. When the same doses of damaging agents were used, these increments were higher in V3 than in AA8. These results indicate that DSBs that are not efficiently repaired can be responsible for the induction of gene amplification. H2O2 stimulates gene amplification as well as gamma-rays, however, at similar levels of amplification induction, chromosome damage was about 50% lower. This suggests that gene amplification can be induced by H2O2 through pathways alternative to a direct DNA damage. Stimulation of gene amplification by H2O2, which is one of the products of the aerobic metabolism, supports the hypothesis that cellular metabolic products themselves can be a source of genome instability
Post-mortem investigations for the diagnosis of sepsis: A review of literature
Full text linkTo date, sepsis is still one of the most important causes of death due to the difficulties concerning the achievement of a correct diagnosis. As well as in a clinical context, also in a medico-legal setting the diagnosis of sepsis can reveal challenging due to the unspecificity of the signs detected during autopsies, especially when no ante-mortem clinical data, laboratory, and cultural results are available. Thus, a systematic review of literature was performed to provide an overview of the main available and updated forensic tools for the post-mortem diagnosis of sepsis. Moreover, the aim of this review was to evaluate whether a marker or a combination of markers exist, specific enough to allow a correct and definite post-mortem diagnosis. The review was conducted searching in PubMed and Scopus databases, and using variable combinations of the keywords “post mortem sepsis diagnosis”, “macroscopic signs”, “morphology”, “histology”, “immunohistochemical markers”, “biochemical markers”, and “forensic microbiology”. The article selection was carried out following specific inclusion and exclusion criteria. A total of 44 works was identified, providing data on morphological aspects of the organs examined, histological findings, immunohistochemical and biochemical markers, and cultural assays. The review findings suggested that the post-mortem diagnosis of sepsis can be achieved by a combination of data obtained from macroscopic and microscopic analysis and microbial investigations, associated with the increased levels of at least two of three biochemical and/or immunohistochemical markers evaluated simultaneously on blood samples
Inhibition of gene amplification in telomerase deficient immortalized mouse embryonic fibroblasts
No full textMutations in genes important for the preservation of genome stability can increase the frequency of gene amplification, a process relevant to tumor development. To investigate whether telomerase, the enzyme deputed to telomere maintenance, also plays a role in gene amplification, we studied the amplification of the carbamyl-P-synthetase, aspartate transcarbamilase, dihydro-orotase (CAD) gene in immortalized embryonic fibroblasts derived from telomerase knockout mice (mTERC(-/-)) of the first and of the sixth generation. As expected, in 9 out of 10 N-(phosphonacetyl)-L-aspartate (PALA) resistant clones derived from wild-type cells, CAD was amplified; in contrast, in none of the 30 PALA resistant clones isolated from the three mTERC(-/-) cell lines we could detect CAD amplification, indicating that, in the absence of telomerase activity, gene amplification is inhibited. The causal relationship between mTERC deficiency and lack of gene amplification was demonstrated by the restoration of CAD gene amplification in two of the three deficient cell lines transfected with mTERC. The lack of amplification in mTERC deficient cells could be related to a defect in the stabilization of the ends of the amplified chromosomes in the absence of telomerase, to a more general effect of telomerase in the regulation of gene expression, including genes involved in amplification, or to a possible interaction of the telomerase RNA with proteins involved in gene amplification
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