Classical work in squid axon reports resting membrane potential is independent of temperature, but our findings suggest that this is not the case for axons in mammalian optic nerve. Refractory period duration changes over 10 times between 37 °C and room temperature, and afterpotential polarity is also acutely temperature sensitive, inconsistent with changes in temperature impacting nerve function only through altered rates of ion channel gating kinetics. Our evidence suggests that the membrane potential is enhanced by warming, an effect reduced by exposure to ouabain. The temperature dependence can be explained if axonal Na(+)/K(+) ATPase continuously expels Na(+) ions that enter axons largely electroneutrally, thereby adding a substantial electrogenic component to the membrane potential. Block of the Na(+) transporter NKCC1 with bumetanide increases refractoriness, like depolarization, indicating that this is a probable route by which Na(+) enters, raising the expectation that the rate of electroneutral Na(+) influx increases with temperature and suggesting a temperature-dependent transmembrane Na(+) cycle that contributes to membrane potential.
Implementing a policy mandating the submission of a completed reporting guideline checklist for observational studies, RCTs and systematic reviews can increase compliance. We advocate this measure for other journals and for other study types.
Alkaptonuria (AKU) is a rare inherited disease resulting from a deficiency of the enzyme homogentisate 1,2‐dioxygenase which leads to the accumulation of homogentisic acid (HGA). AKU is characterized by severe cartilage degeneration, similar to that observed in osteoarthritis. Previous studies suggest that AKU is associated with alterations in cytoskeletal organization which could modulate primary cilia structure/function. This study investigated whether AKU is associated with changes in chondrocyte primary cilia and associated Hedgehog signaling which mediates cartilage degradation in osteoarthritis. Human articular chondrocytes were obtained from healthy and AKU donors. Additionally, healthy chondrocytes were treated with HGA to replicate AKU pathology (+HGA). Diseased cells exhibited shorter cilia with length reductions of 36% and 16% in AKU and +HGA chondrocytes respectively, when compared to healthy controls. Both AKU and +HGA chondrocytes demonstrated disruption of the usual cilia length regulation by actin contractility. Furthermore, the proportion of cilia with axoneme breaks and bulbous tips was increased in AKU chondrocytes consistent with defective regulation of ciliary trafficking. Distribution of the Hedgehog‐related protein Arl13b along the ciliary axoneme was altered such that its localization was increased at the distal tip in AKU and +HGA chondrocytes. These changes in cilia structure/trafficking in AKU and +HGA chondrocytes were associated with a complete inability to activate Hedgehog signaling in response to exogenous ligand. Thus, we suggest that altered responsiveness to Hedgehog, as a consequence of cilia dysfunction, may be a contributing factor in the development of arthropathy highlighting the cilium as a novel target in AKU.
Publication or registration of protocols for recent studies involving human participants in major plastic surgery journals is low. There is considerable scope to improve this and guidance is provided.
Attendance at surgical conferences designed for medical students can significantly increase the desire of high-school students and preclinical medical students to pursue a surgical career, but may not have the same effect for clinical medical students. Surgical conferences may act as an effective means of recruiting students towards choosing a surgical career for a certain subset of students.
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