Should dentists be concerned about the weight of their patients?

This opinion paper considers obesity and its relationship to dental practice. Twenty-three per cent of people in England are estimated to be obese, a figure that is predicted to continue rising. It follows that obese patients are frequently encountered in general dental practice. The authors review the links between obesity and dental health, the possible barriers and challenges to providing dental care for obese people, and how these may be overcome. They also report the findings of a London survey investigating the current provision of specialist dental services for obese patients who cannot be treated in a standard dental chair. Services across London were highly variable and in some areas no provision was identified. The implications of the rising prevalence of obesity for service planners and practitioners are also discussed.     

Distinct classes of c-Kit-activating mutations differ in their ability to promote RUNX1-ETO-associated acute myeloid leukemia

The t(8;21) RUNX1-ETO translocation is one of the most frequent cytogenetic abnormalities in acute myeloid leukemia (AML). In RUNX1-ETO(+) patient samples, differing classes of activating c-KIT receptor tyrosine kinase mutations have been observed. The most common (12%-48%) involves mutations, such as D816V, which occur in the tyrosine kinase domain, whereas another involves mutations within exon 8 in a region mediating receptor dimerization (2%-13% of cases). To test whether distinct subtypes of activating c-KIT mutations differ in their leukemogenic potential in association with RUNX1-ETO, we used a retroviral transduction/transplantation model to coexpress RUNX1-ETO with either c-Kit(D814V) or c-Kit(T417IΔ418-419) in murine hematopoietic stem/progenitor cells used to reconstitute lethally irradiated mice. Analysis of reconstituted animals showed that RUNX1-ETO;c-Kit(D814V) coexpression resulted in 3 nonoverlapping phenotypes. In 45% of animals, a transplantable AML of relatively short latency and frequent granulocytic sarcoma was noted. Other mice exhibited a rapidly fatal myeloproliferative phenotype (35%) or a lethal, short-latency pre-B-cell leukemia (20%). In contrast, RUNX1-ETO;c-Kit(T417IΔ418-419) coexpression promoted exclusively AML in a fraction (51%) of reconstituted mice. These observations indicate that c-Kit(D814V) promotes a more varied and aggressive leukemic phenotype than c-Kit(T417IΔ418-419), which may be the result of differing potencies of the activating c-Kit alleles.     

Sustained telomere length in hepatocytes and cholangiocytes with increasing age in normal liver

Telomeres, a validated biomarker of aging, comprise multiple nucleotide repeats capping chromosomes that shorten with each cell cycle until a critical length is achieved, precipitating cell senescence. Only two previous studies focused on the effect of aging in "normal" liver tissue, but these studies were compromised by small sample size, limited age range, tissue derived from individuals with an increased risk of senescence, and the use of liver homogenates. We developed a robust large-volume, four-color quantitative fluorescent in situ hybridization technique to measure telomere length in large numbers of hepatocytes, Kupffer cells, hepatic stellate cells, CD4-positive and CD8-positive lymphocytes, and cholangiocytes. Following validation against the gold standard (Southern blotting), the technique was applied to normal archived paraffin-embedded liver tissue obtained following reperfusion of implanted donor liver. We studied 73 highly selected donors aged 5-79 years with a short medical illness preceding death and no history of liver disease, reperfusion injury, or steatosis and normal graft function 1-year posttransplantation. Cholangiocytes had significantly longer telomeres compared with all other intrahepatic lineages over a wide age range (P < 0.05). Age-related telomere attrition was restricted to sinusoidal cells (i.e., Kupffer cells [P = 0.0054] and stellate cells [P = 0.0001]). Cholangiocytes and hepatocytes showed no age-related telomere shortening. Conclusion: In normal liver and over a broad age range, cholangiocytes have longer telomeres than all other intrahepatic lineages. Age-related telomere length decline is restricted to Kupffer cells and stellate cells. (HEPATOLOGY 2012).