RESUMO
Lens epithelial cell proliferation and differentiation are naturally well regulated and controlled, a characteristic essential for lens structure, symmetry and function. The effect of ionizing radiation on lens epithelial cell proliferation has been demonstrated in previous studies at high acute doses, but the effect of dose and dose rate on proliferation has not yet been considered. In this work, mice received single acute doses of 0.5, 1 and 2 Gy of radiation, at dose rates of 0.063 and 0.3 Gy/min. Eye lenses were isolated postirradiation at 30 min up until 14 days and flat-mounted. Then, cell proliferation rates were determined using biomarker Ki67. As expected, radiation increased cell proliferation 2 and 24 h postirradiation transiently (undetectable 14 days postirradiation) and was dose dependent (changes were very significant at 2 Gy; P = 0.008). A dose-rate effect did not reach significance in this study (P = 0.054). However, dose rate and lens epithelial cell region showed significant interactions (P < 0.001). These observations further our mechanistic understanding of how the lens responds to radiation.
Assuntos
Cristalino/efeitos da radiação , Animais , Diferenciação Celular/efeitos da radiação , Proliferação de Células/efeitos da radiação , Relação Dose-Resposta à Radiação , Células Epiteliais , Feminino , Humanos , Camundongos Endogâmicos C57BL , Doses de Radiação , Exposição à Radiação , Radiação IonizanteRESUMO
Taybi-Linder syndrome (TALS, OMIM 210710) is a rare autosomal recessive disorder belonging to the group of microcephalic osteodysplastic primordial dwarfisms (MOPD). This syndrome is characterized by short stature, skeletal anomalies, severe microcephaly with brain malformations and facial dysmorphism, and is caused by mutations in RNU4ATAC. RNU4ATAC is transcribed into a non-coding small nuclear RNA which is a critical component of the minor spliceosome. We report here four foetuses and four unrelated patients with RNU4ATAC mutations. We provide antenatal descriptions of this rare syndrome including unusual features found in two twin foetuses with compound heterozygosity for two rare mutations who presented with mild intrauterine growth retardation and atypical dysmorphic facial features. We also carried out a literature review of the patients described up to now with RNU4ATAC mutations, affected either with TALS or Roifman syndrome, a recently described allelic disorder.
Assuntos
Anormalidades Múltiplas/genética , Cardiomiopatias/genética , Nanismo/genética , Retardo do Crescimento Fetal/genética , Síndromes de Imunodeficiência/genética , Deficiência Intelectual Ligada ao Cromossomo X/genética , Microcefalia/genética , Osteocondrodisplasias/genética , RNA Nuclear Pequeno/genética , Doenças Retinianas/genética , Anormalidades Múltiplas/fisiopatologia , Alelos , Cardiomiopatias/fisiopatologia , Criança , Pré-Escolar , Nanismo/fisiopatologia , Feminino , Retardo do Crescimento Fetal/fisiopatologia , Feto , Humanos , Síndromes de Imunodeficiência/fisiopatologia , Lactente , Recém-Nascido , Masculino , Deficiência Intelectual Ligada ao Cromossomo X/fisiopatologia , Microcefalia/fisiopatologia , Mutação , Osteocondrodisplasias/fisiopatologia , Fenótipo , Doenças da Imunodeficiência Primária , Doenças Retinianas/fisiopatologia , Spliceossomos/genéticaRESUMO
The occurrence of mosaic ring chromosome 13 is rare. The mechanism of ring chromosome formation is usually associated with loss of genetic material. We report 2 cases of mosaic ring chromosome 13, resulting in deletion of 13qter. The first patient, a 15 year-old boy, presented a delayed psychomotor development, mental retardation, dysmorphic features and bleeding disorders associated with a de novo terminal 13q34 deletion. The second case was a foetus of 31 weeks with prenatal diagnosis of severe malformation such as holoprosencephaly, congenital cardiac defects, gastro-intestinal abnormalities with intrauterine growth retardation, the molecular analysis showed a de novo deletion encompassing the region 13q31.3-q34.
