Cellular consequences of small supernumerary marker chromosome derived from chromosome 12: mosaicism in daughter and father.

Constitutional genomic imbalances are known to cause malformations, disabilities, neurodevelopmental delay, and dysmorphia and can lead to dysfunctions in the cell cycle. In extremely rare genetic conditions such as small supernumerary marker chromosomes (sSMC), it is important to understand the cellular consequences of this extra marker, as well the factors that contribute to their maintenance or elimination through successive cell cycles and phenotypic impact. The study of chromosomal mosaicism provides a natural model to characterize the effect of aneuploidy on genome stability and compare cells with the same genetic background and environment exposure, but differing in the presence of sSMC. Here, we report the functional characterization of different cell lines from two familial patients with mosaic sSMC derived from chromosome 12. We performed studies of proliferation dynamics, stability, and variability of these cells using fluorescent in situ hybridization (FISH), sister chromatid exchanges (SCE), and conventional staining. We also quantified the telomere-related genomic instability of sSMC cells using 3D telomeric profile analysis by quantitative-FISH. sSMC cells exhibited differences in the cell cycle dynamics compared to normal cells. First, the sSMC cells exhibited lower proliferation index and higher frequency of SCE than normal cells, associated with a higher level of chromosomal instability. Second, sSMC cells exhibited more telomeric-related genomic instability. Lastly, the differences of sSMC cells distribution among tissues could explain different phenotypic repercussions observed in patients. These results will help in our understanding of the sSMC stability, maintenance during cell cycle, and the cell cycle variables involved in the different phenotypic manifestations.

Cellular consequences of small supernumerary marker chromosome derived from chromosome 12: mosaicism in daughter and father

Constitutional genomic imbalances are known to cause malformations, disabilities, neurodevelopmental delay, and dysmorphia and can lead to dysfunctions in the cell cycle. In extremely rare genetic conditions such as small supernumerary marker chromosomes (sSMC), it is important to understand the cellular consequences of this extra marker, as well the factors that contribute to their maintenance or elimination through successive cell cycles and phenotypic impact. The study of chromosomal mosaicism provides a natural model to characterize the effect of aneuploidy on genome stability and compare cells with the same genetic background and environment exposure, but differing in the presence of sSMC. Here, we report the functional characterization of different cell lines from two familial patients with mosaic sSMC derived from chromosome 12. We performed studies of proliferation dynamics, stability, and variability of these cells using fluorescent in situ hybridization (FISH), sister chromatid exchanges (SCE), and conventional staining. We also quantified the telomere-related genomic instability of sSMC cells using 3D telomeric profile analysis by quantitative-FISH. sSMC cells exhibited differences in the cell cycle dynamics compared to normal cells. First, the sSMC cells exhibited lower proliferation index and higher frequency of SCE than normal cells, associated with a higher level of chromosomal instability. Second, sSMC cells exhibited more telomeric-related genomic instability. Lastly, the differences of sSMC cells distribution among tissues could explain different phenotypic repercussions observed in patients. These results will help in our understanding of the sSMC stability, maintenance during cell cycle, and the cell cycle variables involved in the different phenotypic manifestations.

Radioactive synovectomy with Yttrium9° citrate in haemophilic synovitis: Brazilian experience.

Recurrent haemarthroses leading to chronic synovitis and arthropathy remain a major cause of morbidity in patients with haemophilia. Radioactive synovectomy (RS) is considered the first choice of treatment for chronic haemophilic synovitis. The aim of this study was to evaluate the effect of RS with Yttrium(90) citrate (C-Y(90)) in the joints of patients with chronic haemophilic synovitis. From 2003 to 2007, 245 joints (118 knees, 76 elbows, 49 ankles and two shoulders) of 190 patients with haemophilia or von Willebrand disease were submitted to RS with C-Y(90) at Hemocentro de Mato Grosso, Brazil. Forty joints had radiographic Pettersson scores above 8. There were 36 joints of 22 patients with inhibitors to factor VIII. The procedure was safe with low occurrence of adverse events. The main effect was the overall reduction in joint bleeding frequency, from 19.8 to 2.6 per year post-RS. Similar results were obtained in cases with high radiographic scores and in inhibitor patients. Pain reduction was observed in most cases. Average range of motion was maintained or increased 1 year post-RS in most joints. Extension was stable or increased in 88.2% of the knees and 86.5% of the elbows. Ankle plantarflexion was stable or increased in 90.9%, whereas dorsiflexion was maintained or increased in 87.9%. Worsening of the range of motion, when present, ranged from 14 to 17 degrees. We concluded that RS with C-Y(90) represents an important resource for the treatment of chronic haemophilic synovitis, markedly reducing joint bleeding frequency and pain, irrespective of the radiographic stage and inhibitor status.

A computational model for telomere-dependent cell-replicative aging.

Telomere shortening provides a molecular basis for the Hayflick limit. Recent data suggest that telomere shortening also influence mitotic rate. We propose a stochastic growth model of this phenomena, assuming that cell division in each time interval is a random process which probability decreases linearly with telomere shortening. Computer simulations of the proposed stochastic telomere-regulated model provides good approximation of the qualitative growth of cultured human mesenchymal stem cells.