Suzaku Observation of the Diffuse X-Ray Emission from the Open Cluster Westerlund 2: a Hypernova Remnant?

We present the analysis of Suzaku observations of the young open cluster Westerlund 2, which is filled with diffuse X-ray emission. We found that the emission consists of three thermal components or two thermal and one non-thermal components. The upper limit of the energy flux of the non-thermal component is smaller than that in the TeV band observed with H.E.S.S. This may indicate that active particle acceleration has stopped in this cluster, and that the accelerated electrons have already cooled. The gamma-ray emission observed with H.E.S.S. is likely to come from high-energy protons, which hardly cool in contrast with electrons. Metal abundances of the diffuse X-ray gas may indicate the explosion of a massive star in the past.Comment: Accepted for publication in PAS

Telomeres and Cellular Senescence in Metabolic and Endocrine Diseases

A number of observations suggest a close connection between telomere length and mortality and age-related disease, suggesting that telomere length is a useful marker of individual biological aging and the shortening of telomere length is causally related with the pathogenesis in age-related diseases. To date, the significance of telomere length in metabolic and endocrine diseases has also been clarified. It has been reported that obesity, type 2 diabetes mellitus (T2DM), NAFLD, and hypertension were associated with shortened telomere length. In endocrine diseases, polycystic ovary syndrome (PCOS), Cushing’s syndrome, and acromegaly were associated with shortened telomere length. In these conditions, an increased oxidative stress associated with the metabolic and hormonal abnormalities appears to play a pivotal role in the shortened telomere length. Recently, a large population-based study demonstrated that shortened telomeres at baseline were associated with an increased risk of metabolic diseases, suggesting that the shortened telomere itself plays a causal role for the onset or development of the metabolic diseases. In this chapter, the pathophysiological role of shortened telomere length in metabolic and endocrine diseases and the significance of cellular senescence are discussed

Colorectal Neoplasm in Acromegaly: Epidemiology and Underlying Mechanisms

Acromegaly is characterized by autonomous growth hormone (GH) secretion from the pituitary somatotroph adenoma and increased levels of serum insulin-like growth factor I (IGF-I). These conditions are associated with increased morbidity and mortality due to metabolic conditions, cardiovascular diseases, and malignant neoplasms. Among neoplasms, while colorectal neoplasms are a well-known comorbidity in patients with acromegaly, the prevalence of colorectal benign or malignant tumors varies among studies. Although several underlying mechanisms have been proposed, recent studies have unveiled new insights into tumorigenesis. This review focused on the epidemiological studies of colorectal neoplasm in acromegaly and recent advances in the elucidation of the underlying mechanisms

Scaling of soaring seabirds and its implication for the maximum size of flying pterosaurs

The flight ability of animals is restricted by the scaling effects imposed by physical and physiological factors. In comparisons of the power available from muscle and the mechanical power required to fly, theoretical studies have predicted that the margin between the powers should decrease with body size and that flying animals have a maximum body size. However, predicting an absolute value of this upper limit has been difficult because wing morphology and flight styles vary among species. Albatrosses and petrels have long, narrow, aerodynamically efficient wings and are considered to be soaring birds. Here, using animal-borne accelerometers, we show that scaling analyses of wing-flapping frequencies in these seabirds indicate that the maximum size limit for soaring animals is a body mass of 41 kg and a wingspan of 5.1 m. Soaring seabirds were observed to have two modes of flapping frequencies: vigorous flapping during takeoff and sporadic flapping during cruising flight. In these species, high and low flapping frequencies were found to scale with body mass (_mass_ ^-0.30^ and _mass_ ^-0.18^) in a manner similar to the predictions from biomechanical flight models (_mass_ ^-1/3^ and _mass_ ^-1/6^). The scaling relationships predicted that animals larger than the limit will not be able to flap fast enough to stay aloft under unfavourable wind conditions. Our result therefore casts doubt on the flying ability of large, extinct pterosaurs. The largest extant soarer, the wandering albatross, weighs about 10 kg, which might be a pragmatic limit to maintain a safety margin for sustainable flight and to survive in a variable environment