Molecular Biophysics
It’s not Just Dentistry, It’s Dentistry and Oral Surgery!
When I completed my residency at the University of Pennsylvania School of Veterinary Medicine (Penn Vet) in 2000, I felt comfortable performing a number of dental and oral surgical diagnostic and therapeutic procedures in dogs and cats. They included oral examination, dental radiography, nerve blocks, dental cleaning, periodontal surgery, tooth extraction, endodontic treatment, restorations and prosthodontic crowns, oral tumor resections, jaw fracture repair, palate defect surgery, temporomandibular joint procedures, and regional lymph node and salivary gland resections.Preface
This issue of Veterinary Clinics of North America: Equine Practice builds on the foundation started in earlier issues of Veterinary Clinics of North America: Equine Practice that were topical on laminitis. This issue is an expanded and thoroughly updated issue that provides our fellow colleagues with a comprehensive and thorough resource for the “common” and “less common” problems of the equine foot and not just focused on laminitis. The information is the most exhaustive of any of the previous publications on the equine foot, while offering a point-by-point discussion of best practices when caring for the foot.Corrigendum to ‘Opioid Free Ureteroscopy: What is the True Failure Rate?’ [Urology Vol. 154 (2021) pp. 89-95]
The authors regret that there is a typo in the Results section of the Abstract. “In the total cohort, benzodiazepine users had a lower risk of OF-URS failure on multivariate analysis” should read “benzodiazepine users had a higher risk of OF-URS failure”.Point-of-Care Ultrasound: —The Awakening of a Sleeping Giant
In 1999, as a general practitioner, I declared my first attempt at learning ultrasound a failure after taking an abdominal ultrasound course. Thus, 7 years later as a resident in emergency and critical care (2005-2007), I was resistant to making FAST ultrasound part of my clinical research requirement. The phrase by my Intern Director (1991), the late Dr Michael Garvey, has always been part of my daily practice since: “never send a patient out the door (home) with something you could easily have diagnosed.” Shortly after learning and routinely applying AFAST and TFAST as an extension of the physical exam in 2005 (and later Vet BLUE, 2010), these FAST ultrasound examinations became part of my quick assessment tests.Consent, Cryopreserved Sperm, and Posthumous Conception: Navigating the Ethical Maze
Recent years have borne witness to 2 ongoing, interrelated phenomena: an oft-publicized decline in male fertility and mounting interest in sperm cryopreservation.1 With heavier utilization of sperm freezing and banking services, a slew of scarcely explored legal-ethical issues rise to the forefront. Chief among these is the question of posthumous conception: what happens to frozen sperm after its donor has died? This is no mere academic point; it implicates parenthood, bodily autonomy, a partner's grieving process, estate distribution, and entitlement to Social Security benefits, among myriad others.Mapping invisible epitopes by NMR spectroscopy
Defining discontinuous antigenic epitopes remains a substantial challenge, as exemplified by the case of lipid transfer polyproteins, which are common pollen allergens. Hydrogen/deuterium exchange monitored by NMR can be used to map epitopes onto folded protein surfaces, but only if the complex rapidly dissociates. Modifying the standard NMR-exchange measurement to detect substoichiometric complexes overcomes this time scale limitation and provides new insights into recognition of lipid transfer polyprotein by antibodies.Shining light on rhodopsin selectivity: How do proteins decide whether to transport H+ or Cl–?
The versatile microbial rhodopsin family performs a variety of biological tasks using a highly conserved architecture, making it difficult to understand the mechanistic basis for different functions. Besaw et al. now report structures of a recently discovered cyanobacterial Cl−-pumping rhodopsin and its functionally divergent mutant that reveal how these transmembrane proteins create a gradient of activity with subtle changes. These insights are paralleled by a second recent report, which in combination answers long-standing questions about rhodopsin selectivity and will facilitate future engineering efforts.PSI relieves the pressure of membrane fusion
Some plant proteases contain a latent sequence known as the plant-specific insert (PSI) that, upon release from the full protease sequence, initiates membrane fusion to defend from pathogens. However, the mechanism by which it exerts its effects has been unclear. Zhao et al. report an elegant integration of biophysical experiments and molecular dynamics simulations to reveal events leading up to PSI-mediated membrane fusion. Their results demonstrate a pH-dependent monomer-to-dimer transition, clear evidence of membrane association, and probable structures of prefusion intermediates.Entropy provides an unexpected shield in photosynthesis
Vascular plants combat the excess photon bombarding of high-light conditions with several protective mechanisms. Despite decades of extensive research, new regulatory mech-anisms for photoprotection may remain unknown. Kim et al. now report that the monomeric disordered form of photosystem II (PSII), which is present in higher abundance in the native thylakoid membrane in response to high light, possesses an energy-quenching capability superior to that of the multimeric ordered phase, suggesting a new shielding strategy against high-light stress by altering the macro-organization of PSII supercomplexes.A protein folding intermediate pulls its weight
Proteins must acquire and maintain a specific fold to execute their biochemical function(s). In solution, unfolded proteins typically find this native structure through a biased sampling of preferred intermediate conformations. However, the initial search for these structures begins during protein synthesis, and it is unclear how much interactions between the ribosome and nascent polypeptide skew folding pathways. In this issue, Jensen and colleagues use a ribosomal force–profiling assay to show that RNase H forms a similar folding intermediate on and off the ribosome.Forcing the ribosome to change its message
Mechanical forces can be generated when nascent protein segments are integrated into a membrane. These forces are then transmitted through the nascent protein to the ribosome's catalytic core, but only a few biological consequences of this process have been identified to date. In this issue, Harrington et al. present evidence that these forces form a conserved mechanism to influence the efficiency of ribosomal frameshifting during translation of viral RNA, indicating that mechanical forces may play a broader regulatory role in translation than previously appreciated.Driving tau into phase-separated liquid droplets
Liquid–liquid phase separation of tau protein has been implicated in normal biological function as well as neurodegenerative diseases, including Alzheimer's. However, knowledge about these links is still scant, and the mechanisms driving tau into liquid droplets are poorly understood. A simplified in vitro system that uses unmodified human tau protein now suggests electrostatic interactions provide the basic instructions underlying liquid droplet formation.How a fortuitous collaboration helped catalyze new insights into helper proteins
What a way to begin a scientific career: Two newly independent researchers are brought together at a conference that was only possible because their country has just been reunified. In discussing their work, they discover that each holds half of a research project in their hands: The East German, Matthias Gaestel, can provide the critical protein for West German Johannes Buchner's robust assays. In their cross-country collaboration, they get clear and compelling data defining the previously enigmatic small heat shock proteins as molecular chaperones.
