Activity patterns and reproductive behavior of the Critically Endangered Bermuda skink (Plestiodon longirostris).

The study of rare or cryptic species in zoos can provide insights into natural history and behavior that would be difficult to obtain in the field. Such information can then be used to refine population assessment protocols and conservation management. The Bermuda skink (Plestiodon longirostris) is an endemic Critically Endangered lizard. Chester Zoo's successful conservation breeding program is working to safeguard, increase and reinforce skink populations in the wild. A key aim of this program is to develop our understanding of the behavior of this species. In this study, using 24 h video recordings, we examined the daily activity patterns, basking behavior and food preferences of four pairs of Bermuda skinks. The skinks displayed a bimodal pattern of activity and basking, which may have evolved to avoid the strength of the midday sun in exposed habitats in Bermuda. Captive Bermuda skinks appear to prefer a fruit-based diet to orthopteran prey. We also documented their reproductive behavior and compared it against two closely related species. Although there were many similarities between the courtship and mating behaviors of the three species, there was a significantly shorter period of cloacal contact in the Bermuda skink. Oophagia was also documented for the first time in this species. This knowledge has enabled the evaluation of the current ex-situ management practices of this species, filled gaps in knowledge that would be challenging to obtain in the field, and enabled the enhancement of both animal husbandry and reproductive success for the conservation breeding program.

Online information about the management of anterior cruciate ligament ruptures in Australia: A content analysis.

BACKGROUND: Most people who suffer an anterior cruciate ligament (ACL) injury search for information online. OBJECTIVES: Summarise the proportion of webpages on ACL rupture management that present evidence-based information. DESIGN: Content analysis. METHODS: We examined webpage information on ACL ruptures identified through (1) Google searches using terms synonymous with 'anterior cruciate ligament rupture' and searching 'knee surgeon' linked to each Australian capital city, and (2) websites of professional associations. The primary outcome was the proportion of webpages that suggest people can return to at least some form of sport with non-surgical management. Secondary outcomes included webpage information on return to sport with ACL reconstruction (ACLR) and non-surgical management, benefits, harms, and risk of osteoarthritis related to these options, and activity modification. RESULTS: Out of 115 webpages analysed, 48% suggested people can return to at least some form of sport with non-surgical management. Almost half of webpages suggested most people will return to some form of sport following ACLR (41%) and mentioned benefits of ACLR (43%). Fewer webpages mentioned benefits of non-surgical management (14%), approximately two in three people return to pre-injury level of sport following ACLR (4%), risk of re-injury following ACLR (23%), most people return to sport within 9 months of ACLR (27%), activity modification as a management approach (20%), and ACLR will reduce the risk of osteoarthritis (23%). CONCLUSION: Most online information on ACL rupture management isn't aligned with the best available evidence. Inaccurate information could mislead patients' treatment choices and create unrealistic expectations for return to sport.

Mechanical sensitivity of red blood cells improves in individuals with hemochromatosis following venesection therapy.

BACKGROUND: Individuals with hereditary hemochromatosis (HH) receive frequent blood withdrawals (ie, venesections) as part of their primary treatment to assist in normalizing blood iron levels. It remains unclear whether this source of blood is suitable for use in blood product development, as current data indicate that red blood cell (RBC) deformability, both before and after shear stress exposure, is impaired in individuals with HH, relative to healthy controls. Given that venesection therapy is known to significantly reduce circulating iron levels in individuals with HH, the current study examined whether venesection therapy is effective at improving RBC mechanical properties, both before and after shear stress exposure, in individuals with HH. STUDY DESIGN AND METHODS: Blood samples were initially collected from untreated HH patients (age, 61 ± 9 years; 14% female) undergoing their first venesection, and then again during their second (approx. 9 weeks later) and third (approx. 16 weeks later) venesections. RBC deformability was measured at each time point with a commercial ektacytometer. Moreover, to determine cell responses to mechanical stimuli, the mechanical sensitivity of blood samples was determined at each time point. RESULTS: The salient findings indicate that venesection therapy used for managing plasma ferritin concentration significantly improves the cellular deformability of RBC in individuals with HH. Further, the sensitivity of RBC to supraphysiological mechanical stress is decreased (ie, improved) in a dose-response fashion with routine venesection. CONCLUSION: While cellular mechanics of RBC from individuals with HH are impaired when untreated, venesection therapy significantly improves cellular properties of RBC, supporting the use of venesections in blood product development from individuals with well-managed HH.

Hemochromatosis alters the sensitivity of red blood cells to mechanical stress.

BACKGROUND: Hemochromatosis (HH) is characterized by chronic iron accumulation, leading to deleterious effects to various organ systems. A common approach to managing iron load involves large-volume venesection. Some countries authorize HH venesections to be used in the development of transfusable blood products, although concerns remain regarding suitability. Due to the high oxidative load associated with hyperferritinemia, it has been proposed that HH blood products may be susceptible to mechanical damage. This is particularly relevant given that typical blood product destinations (eg, transfusion, cardiopulmonary bypass) expose blood to supraphysiologic levels of mechanical stress. We sought to explore the mechanical tolerance of red blood cells (RBC) derived from HH venesections to varied magnitudes and durations of sublethal shear stress. STUDY DESIGN AND METHODS: Initially, 110 individuals with HH were recruited; to eliminate the effects of comorbidities, only those who were untreated and uncomplicated were included for comparisons with age-matched healthy controls (Con). RBC were exposed to 25 discrete magnitudes (1-64 Pa) and durations (1-64 seconds) of shear stress. Cellular deformability was assessed before, and immediately after, each shear exposure. RESULTS: In the absence of prior shear exposure, RBC deformability of HH was significantly decreased by 11.5%, compared with Con. For both HH and Con, supraphysiologic shear exposure significantly impaired RBC deformability, although the rate and magnitude of deterioration were elevated for HH. CONCLUSION: Given that blood products are commonly exposed to high-shear environments (eg, during high-volume transfusion), venesections from asymptomatic and untreated individuals with HH appear suboptimal for the development of therapeutic RBCs.

Beyond oxygen transport: active role of erythrocytes in the regulation of blood flow.

It was classically thought that the function of mammalian red blood cells (RBCs) was limited to serving as a vehicle for oxygen, given the cells' abundance of cytosolic hemoglobin. Over the past decades, however, accumulating evidence indicates that RBCs have the capacity to sense low-oxygen tensions in hypoxic tissues, and, subsequently, release signaling molecules that influence the distribution of blood flow. The precise mechanisms that facilitate RBC modulation of blood flow are still being elucidated, although recent evidence indicates involvement of 1) adenosine triphosphate, capable of binding to purinergic receptors located on the vascular wall before initiating nitric oxide (NO; a powerful vasodilator) production in endothelial cells, and/or 2) nonvascular NO, which is now known to have several modes of production within RBCs, including an enzymatic process via a unique isoform of NO synthase (i.e., RBC-NOS), which has potential effects on the vascular smooth muscle. The physical properties of RBCs, including their tendency to form three-dimensional structures in low shear flow (i.e., aggregation) and their capacity to elongate in high shear flow (i.e., deformability), are only recently being viewed as mechanotransductive processes, with profound effects on vascular reactivity and tissue perfusion. Recent developments in intracellular signaling in RBCs, and the subsequent effects on the mechanical properties of blood, and blood flow, thus present a vivid expansion on the classic perspective of these abundant cells.

Susceptibility of density-fractionated erythrocytes to subhaemolytic mechanical shear stress.

INTRODUCTION:: Accumulating evidence demonstrates that subhaemolytic mechanical stresses, typical of circulatory support, induce physical and biochemical changes to red blood cells. It remains unclear, however, whether cell age affects susceptibility to these mechanical forces. This study thus examined the sensitivity of density-fractionated red blood cells to sublethal mechanical stresses. METHODS:: Red blood cells were isolated and washed twice, with the least and most dense fractions being obtained following centrifugation (1500 g × 5 min). Red blood cell deformability was determined across an osmotic gradient and a range of shear stresses (0.3-50 Pa). Cell deformability was also quantified before and after 300 s exposure to shear stresses known to decrease (64 Pa) or increase (10 Pa) red blood cell deformability. The time course of accumulated sublethal damage that occurred during exposure to 64 Pa was also examined. RESULTS:: Dense red blood cells exhibited decreased capacity to deform when compared with less dense cells. Cellular response to mechanical stimuli was similar in trend for all red blood cells, independent of density; however, the magnitude of impairment in cell deformability was exacerbated in dense cells. Moreover, the rate of impairment in cellular deformability, induced by 64 Pa, was more rapid for dense cells. Relative improvement in red blood cell deformability, due to low-shear conditioning (10 Pa), was consistent for both cell populations. CONCLUSION:: Red blood cell populations respond differently to mechanical stimuli: older (more dense) cells are highly susceptible to sublethal mechanical trauma, while cell age (density) does not appear to alter the magnitude of improved cell deformability following low-shear conditioning.

Haemochromatosis: Pathophysiology and the red blood cell1.

Haemochromatosis remains the most prevalent genetic disorder of Caucasian populations in Australia and the United States, occurring in ∼1 of 200 individuals and having a carrier frequency of 10-14%. Hereditary haemochromatosis is an autosomal recessive condition, that is phenotypically characterised by a gradual accumulation of iron, above and beyond that required for biological function. Once the binding capacity of iron carriers reaches saturation, the highly reactive free iron generates radicals that may lead to widespread cellular dysfunction. Thus, the compounding effects of systemic iron overload and the associated oxidative stress in untreated haemochromatosis patients results in tissue damage precipitating severe complications, including: liver cirrhosis, hepatocellular cancer, cardiomyopathy, and diabetes. The primary treatment indicated for individuals with haemochromatosis is venesection therapy (i.e., regular bloodletting of ∼450 mL). Given the frequency of venesection required to decrease and normalise the elevated iron levels, this population may serve as a valuable source of blood products which are in short supply. While the complications associated with elevated iron deposits are frequently reported, the influence of haemochromatosis on the rheological properties of blood and red blood cells (RBC) - major determinants of microvascular blood flow and tissue perfusion - are poorly understood. Limited studies investigating haemorheology in patients with haemochromatosis have reported altered physical properties of blood, which may partly explain the comorbidities associated with the disorder. The current review will explore the aetiology, pathology, and clinical implications of haemochromatosis disease and the associated oxidative stress, with particular emphasis on RBC.