RESUMO
Shave excision is a simple and cost-effective technique for the removal of suitable skin lesions. We performed a prospective study over six months, collecting data from pigmented lesions that were treated with shave excision by dermatologists. Only shave excisions with the intent to remove the lesion in toto were included. A total of 349 lesions were included in this study, 50 (14%) of these were melanomas and no melanoma diagnosed had deep margin involvement, while 13 (26%) had lateral margin involvement.
Assuntos
Melanoma/patologia , Melanoma/cirurgia , Nevo Pigmentado/cirurgia , Neoplasias Cutâneas/patologia , Neoplasias Cutâneas/cirurgia , Adulto , Idoso , Biópsia , Procedimentos Cirúrgicos Dermatológicos , Feminino , Humanos , Masculino , Margens de Excisão , Melanoma/diagnóstico , Pessoa de Meia-Idade , Neoplasia Residual , Nevo Pigmentado/patologia , Estudos Prospectivos , Reoperação , Pele/patologia , Neoplasias Cutâneas/diagnósticoRESUMO
We recently identified a novel germinal center GTPase, SLIP-GC, that localizes to replication factories in B cells and that, when reduced, induces DNA breaks in lymphoma B cell lines in an activation-induced deaminase (AID)-dependent manner. Herein, we generated mice deficient in SLIP-GC and examined the impact of SLIP-GC deficiency in immunoglobulin hypermutation and class switch recombination, both AID-dependent mechanisms. SLIP-GC-deficient mice experienced a substantial increase in mutations at G:C base pairs at the region downstream of JH4 in the immunoglobulin heavy chain locus. This change was reflected in the overall mutation frequency, and it was associated with an increase in transitions from G:C base pairs, a hallmark of AID-mediated deamination during replication. In addition, G:C transitions at non-immunoglobulin loci also increased in these mice. Given the intracellular localization of SLIP-GC to sites of replicating DNA, these results suggest that SLIP-GC protects replicating DNA from AID-mediated deamination of cytosines in both strands.
Assuntos
Citidina Desaminase/metabolismo , GTP Fosfo-Hidrolases/biossíntese , GTP Fosfo-Hidrolases/genética , Imunoglobulinas/genética , Hipermutação Somática de Imunoglobulina/genética , Animais , Linfócitos B/citologia , Linfócitos B/metabolismo , Citidina Desaminase/genética , Citosina/química , Análise Mutacional de DNA , Replicação do DNA , Genótipo , Centro Germinativo/metabolismo , Switching de Imunoglobulina , Ativação Linfocitária , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Modelos Genéticos , Nódulos Linfáticos Agregados/metabolismoRESUMO
Like most phages with double-stranded DNA, phage T4 exits the infected host cell by a lytic process requiring, at a minimum, an endolysin and a holin. Unlike most phages, T4 can sense superinfection (which signals the depletion of uninfected host cells) and responds by delaying lysis and achieving an order-of-magnitude increase in burst size using a mechanism called lysis inhibition (LIN). T4 r mutants, which are unable to conduct LIN, produce distinctly large, sharp-edged plaques. The discovery of r mutants was key to the foundations of molecular biology, in particular to discovering and characterizing genetic recombination in T4, to redefining the nature of the gene, and to exploring the mutation process at the nucleotide level of resolution. A number of r genes have been described in the past 7 decades with various degrees of clarity. Here we describe an extensive and perhaps saturating search for T4 r genes and relate the corresponding mutational spectra to the often imperfectly known physiologies of the proteins encoded by these genes. Focusing on r genes whose mutant phenotypes are largely independent of the host cell, the genes are rI (which seems to sense superinfection and signal the holin to delay lysis), rIII (of poorly defined function), rIV (same as sp and also of poorly defined function), and rV (same as t, the holin gene). We did not identify any mutations that might correspond to a putative rVI gene, and we did not focus on the famous rII genes because they appear to affect lysis only indirectly.
Assuntos
Bacteriófago T4/genética , Mutação , Proteínas Virais/genética , Proteínas Virais/metabolismo , Sequência de Aminoácidos , Bacteriófago T4/fisiologia , Sequência de Bases , Escherichia coli/virologia , Lisogenia , Dados de Sequência MolecularRESUMO
Genome instability continuously presents perils of cancer, genetic disease and death of a cell or an organism. At the same time, it provides for genome plasticity that is essential for development and evolution. We address here the genome instability confined to a small fraction of DNA adjacent to free DNA ends at uncapped telomeres and double-strand breaks. We found that budding yeast cells can tolerate nearly 20 kilobase regions of subtelomeric single-strand DNA that contain multiple UV-damaged nucleotides. During restoration to the double-strand state, multiple mutations are generated by error-prone translesion synthesis. Genome-wide sequencing demonstrated that multiple regions of damage-induced localized hypermutability can be tolerated, which leads to the simultaneous appearance of multiple mutation clusters in the genomes of UV- irradiated cells. High multiplicity and density of mutations suggest that this novel form of genome instability may play significant roles in generating new alleles for evolutionary selection as well as in the incidence of cancer and genetic disease.
Assuntos
Quebras de DNA de Cadeia Dupla/efeitos da radiação , Dano ao DNA/efeitos da radiação , Variação Genética , Instabilidade Genômica/genética , Telômero/efeitos da radiação , Dano ao DNA/genética , Mutação/efeitos da radiação , Proteínas de Saccharomyces cerevisiae/genética , Saccharomycetales , Análise de Sequência de DNA , Telômero/genética , Proteínas de Ligação a Telômeros/genética , Raios UltravioletaRESUMO
Neutrophil recruitment to the lung after lipopolysaccharide (LPS; endotoxin) inhalation is primarily dependent on Toll-like receptor 4 (Tlr4) signaling, because it is virtually absent in mice deficient in Tlr4. However, among strains wild type for Tlr4, the magnitude of neutrophil recruitment to the lung after LPS inhalation is variable, suggesting the involvement of genes other than Tlr4. To identify genes associated with the inflammatory response to inhaled LPS, we evaluated the transcriptional response in lungs of 12 inbred strains of mice, 8 which are wild type for Tlr4 and 4 of which lack functional Tlr4. Using the promoter integration in microarray analysis algorithm, we scanned our gene list for transcription factor-binding sites significantly overrepresented among Tlr4 wild-type strains with high neutrophil influx in the lung after LPS inhalation. This analysis identified the interferon (IFN)-stimulated response element (ISRE) as the most overrepresented transcription factor (present in 24% of the promoters) associated with the neutrophil influx to the lower respiratory tract. To test the validity of this observation, we evaluated IFN-gamma-deficient mice and found that the presence of IFN-gamma is essential for robust neutrophil recruitment to the lower respiratory tract and modulation of key regulatory cytokines and chemokines after LPS inhalation. In conclusion, using a genomic approach, we identified the ISRE as a transcriptional element associated with the neutrophil response to inhaled LPS and demonstrated for the first time that IFN-gamma plays a critical role in LPS-induced neutrophil recruitment to the lower airways.