Myosin isoform expression in the prehensile tails of didelphid marsupials: functional differences between arboreal and terrestrial opossums.

Prehensile tails are defined as having the ability to grasp objects and are commonly used as a fifth appendage during arboreal locomotion. Despite the independent evolution of tail prehensility in numerous mammalian genera, data relating muscle structure, physiology, and function of prehensile tails are largely incomplete. Didelphid marsupials make an excellent model to relate myosin heavy chain (MHC) isoform fiber type with structure/function of caudal muscles, as all opossums have a prehensile tail and tail use varies between arboreal and terrestrial forms. Expanding on our previous work in the Virginia opossum, this study tests the hypothesis that arboreal and terrestrial opossums differentially express faster versus slower MHC isoforms, respectively. MHC isoform expression and percent fiber type distribution were determined in the flexor caudae longus (FCL) muscle of Caluromys derbianus (arboreal) and Monodelphis domestica (terrestrial), using a combination of gel electrophoresis and immunohistochemistry analyses. C. derbianus expresses three MHC isoforms (1, 2A, 2X) that are distributed (mean percentage) as 8.2% MHC-1, 2.6% 1/2A, and 89.2% 2A/X hybrid fibers. M. domestica also expresses MHC-1, 2A, and 2X, in addition to the 2B isoform, distributed as 17.0% MHC-1, 1.3% 1/2A, 9.0% 2A, 75.2% 2A/X, and 0.3% 2X/B hybrid fibers. The distribution of similar isoform fiber types differed significantly between species (P < 0.001). Although not statistically significant, C. derbianus was observed to have larger cross-sectional area (CSA) for each corresponding fiber type along with a greater amount of extra-cellular matrix. An overall faster fiber type composition (and larger fibers) in the tail of an arboreal specialist supports our hypothesis, and correlates with higher muscle force required for tail hanging and arboreal maneuvering on terminal substrates. Conversely, a broader distribution of highly oxidative fibers in the caudal musculature is well suited for tail nest building/remodeling behaviors of terrestrial opossums.

What stops us from healing the healers: a survey of help-seeking behaviour, stigmatisation and depression within the medical profession.

BACKGROUND: Doctors are poor at help-seeking, particularly for mental ill health; attitudes of colleagues reflecting stigmatisation may be important factors influencing decisions to seek support. AIMS: This article focuses on doctors' attitudes to depression rather than mental illness in general. It seeks to determine the extent to which doctors perceive depression is stigmatised within the medical profession and whether the level of perceived stigma affects patterns of help-seeking behaviour. METHOD: : A postal survey was sent to 1488 General Practitioners and 152 psychiatrists in Devon and Cornwall. Questions assessed stigmatising attitudes to depression; help-seeking behaviour and barriers to help-seeking. Prevalence of self-reported depression and time off work was measured. RESULTS: The response rate was 76.6%. Doctors perceived that many of their profession hold stigmatising views of depression. Some 46.2% of respondents reported that they had suffered an episode of depression. Help-seeking was significantly reduced in those with a history of depression. Barriers to help-seeking were reported as letting colleagues down (73.1%), confidentiality (53.4%), letting patients down (51.9%) and career progression (15.7%). Gender and a history of depression significantly affected help-seeking behaviour and perceived stigmatisation. Higher levels of perceived stigma increased concerns about help-seeking and reduced help-seeking from own GP or colleagues. CONCLUSION: Stigma associated with depression in doctors is endemic in the medical profession and the level of perceived stigma is related to reduced help-seeking behaviour. Efforts need to be made by the profession to reduce the stigma anticipated by those who become depressed, to enable appropriate help-seeking and support.