Mammalian species differ dramatically in telomere biology. Species larger than 5-10 kg repress somatic telomerase activity and have shorter telomeres, leading to replicative senescence. It has been proposed that evolution of replicative senescence in large-bodied species is an anti-tumour mechanism counteracting increased risk of cancer due to increased cell numbers. By contrast, small-bodied species express high telomerase activity and have longer telomeres. To counteract cancer risk due to longer lifespan, long-lived small-bodied species evolved additional telomere-independent tumour suppressor mechanisms. Here, we tested the connection between telomere biology and tumorigenesis by analysing the propensity of fibroblasts from 18 rodent species to form tumours. We found a negative correlation between species lifespan and anchorage-independent growth. Small-bodied species required inactivation of Rb and/or p53 and expression of oncogenic H-Ras to form tumours. Large-bodied species displayed a continuum of phenotypes requiring additional genetic 'hits' for malignant transformation. Based on these data we refine the model of the evolution of tumour suppressor mechanisms and telomeres. We propose that two different strategies evolved in small and large species because small-bodied species cannot tolerate small tumours that form prior to activation of the telomere barrier, and must instead use telomere-independent strategies that act earlier, at the hyperplasia stage.This article is part of the theme issue 'Understanding diversity in telomere dynamics'.

Differences in the way human and mouse fibroblasts experience senescence in culture had long puzzled researchers. While senescence of human cells is mediated by telomere shortening, Parrinello et al. demonstrated that senescence of mouse cells is caused by extreme oxygen sensitivity. It was hypothesized that the striking difference in oxygen sensitivity between mouse and human cells explains their different rates of aging. To test if this hypothesis is broadly applicable, we cultured cells from 16 rodent species with diverse lifespans in 3% and 21% oxygen and compared their growth rates. Unexpectedly, fibroblasts derived from laboratory mouse strains were the only cells demonstrating extreme sensitivity to oxygen. Cells from hamster, muskrat, woodchuck, capybara, blind mole rat, paca, squirrel, beaver, naked mole rat and wild-caught mice were mildly sensitive to oxygen, while cells from rat, gerbil, deer mouse, chipmunk, guinea pig and chinchilla showed no difference in the growth rate between 3% and 21% oxygen. We conclude that, although the growth of primary fibroblasts is generally improved by maintaining cells in 3% oxygen, the extreme oxygen sensitivity is a peculiarity of laboratory mouse strains, possibly related to their very long telomeres, and fibroblast oxygen sensitivity does not directly correlate with species' lifespan.

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Objectives The study aimed to evaluate patient satisfaction with speech‐language therapy televisits and to identify factors influencing the level of satisfaction. Methods Participants were recruited from an academic tertiary voice and swallowing center who had completed ≥1 telehealth session of speech‐language therapy with a speech‐language pathologist between March, 2020 and April, 2021. Patient satisfaction was assessed using the Short Assessment of Patient Satisfaction (SAPS), a validated 7‐item survey. Demographic characteristics of participants were collected from a review of patient charts. Results 65/239 patients completed the SAPS survey, representing a response rate of 27%. The average age of study participants was 54.92 ± 16.45 years, with 49.2% identifying as female, 33.9% as male, and 16.9% as trans‐female. The mean SAPS score was 22.60 ± 3.89, with 84.62% of patients satisfied or very satisfied with their visit. Patients were most satisfied with provider respect (3.91 ± 0.34) and care received (3.74 ± 0.64), and least satisfied with visit length (2.32 ± 1.38) and explanation of treatment results (2.62 ± 1.72). Patient satisfaction was positively correlated with younger age and an increased number of televisits. Satisfaction did not differ significantly by gender identity, type of therapy received, insurance type, travel distance, or prior in‐person therapy. Conclusion Clinicians are able to achieve high patient satisfaction with speech‐language therapy when delivered by telehealth. Patient satisfaction remained high across diverse patient populations and range of clinical needs. Clinicians should remain cognizant of the unique limitations of older patients when conducting telehealth visits. Lay Summary Clinicians are able to achieve high patient satisfaction with speech‐language therapy when delivered via telehealth. Satisfaction remained high regardless of gender identity, type of therapy received, type of insurance, travel distance, or completion of prior in‐person therapy. Level of Evidence 4 Laryngoscope, 133:895–900, 2023