Cytomegalovirus as a cause of recurrent corneal endotheliitis in the Canadian population.

OBJECTIVE: To report the clinical manifestations, response to antiviral treatment, and long-term visual outcomes of cytomegalovirus endotheliitis in a Canadian population. DESIGN: Retrospective case series. PARTICIPANTS: A total of 9 eyes of 7 patients referred to a cornea subspecialty clinic in a major Canadian centre with corneal endotheliitis. METHODS: A retrospective review of all patients presenting with corneal endotheliitis to 1 corneal surgeon was completed. Patients underwent anterior chamber biopsy with positive cytomegalovirus polymerase chain reaction. All patients received systemic valganciclovir for a minimum of 3 months. Primary outcomes included visual acuity, intraocular pressure control, medication dependence, and corneal status. RESULTS: The average follow-up was 76.4 ± 11.8 months. Two patients had bilateral disease. Corneal manifestations included linear, disciform, and circinate patterns of endotheliitis. Best-corrected visual acuity improved from a mean of 0.48 ± 0.19 logMAR at presentation to 0.24 ± 0.11 logMAR at last follow-up. Intraocular pressure decreased from a peak of 35 ± 3.1 mm Hg to 14.2 ± 4.3 mm Hg. Antiglaucoma medications were reduced from 2.6 ± 0.45 to 0.89 ± 0.29 agents. Two eyes required endothelial transplantation. Valganciclovir therapy was well tolerated by all patients; at the time of last follow-up, all patients were stable on low-dose valganciclovir at an average dose of 1395 mg per week. CONCLUSIONS: Cytomegalovirus is an uncommon but clinically significant cause of corneal endotheliitis that must be considered in the differential diagnosis of corneal endotheliitis, even in the immunocompetent population. Our results support prior findings that this entity responds robustly to oral valganciclovir and demonstrate for the first time the efficacy of chronic low-dose antiviral maintenance therapy.

Novel open-source 3D-printed eye mount (TEMPO) for the ophthalmology wet lab.

OBJECTIVE: Procuring an affordable eye mount that can stabilise a cadaveric eye and simulate a patient's normal facial contours represents an ongoing challenge in the ophthalmology simulation wet lab, with notable limitations to all currently available commercial options. This project uses computer-assisted design and three-dimensional (3D)-printing techniques to tackle these challenges for ophthalmologic surgical training. METHODS AND ANALYSIS: Proof-of-concept study. Using Autodesk Fusion 360, we designed and 3D-printed a modular device that consists of 11 pieces forming a head structure. Standard OR tubing and syringes were adapted to create an adjustable-suction system to affix cadaveric eyes. Further modular inserts were customised to house non-cadaveric simulation eyes. RESULTS: Three-dimensional eye mount for procedures in ophthalmology (TEMPO) reliably fixed a cadaveric eye in stable position throughout surgical manipulation. Trainees were able to drape and practice appropriate hand positioning while corneal suturing. Overall, this model was affordable, at a cost of approximately $C200 to print. The modular nature renders individual pieces convenient for replacement and customisable to simulate regional anatomical variation and accommodate non-cadaveric eyes. CONCLUSIONS: TEMPO represents an affordable, high-fidelity alternative to existing commercially available eye mounts. It reliably fixates cadaveric and simulation eyes and provides an enhanced surgical training experience by way of its realistic facial contours. It is released as an open-source computer-aided design file, customisable to interested trainees with appropriate software and 3D-printing capacity.

Developmental Maturation of Functional Coupling Between Ventilatory Oscillators in the American Bullfrog.

Many vital motor behaviors - including locomotion, swallowing, and breathing - appear to be dependent upon the activity of and coordination between multiple endogenously rhythmogenic nuclei, or neural oscillators. Much as the functional development of sensory circuits is shaped during maturation, we hypothesized that coordination of oscillators involved in motor control may likewise be maturation-dependent, i.e., coupling and coordination between oscillators change over development. We tested this hypothesis using the bullfrog isolated brainstem preparation to study the metamorphic transition of ventilatory motor patterns from early rhythmic buccal (water) ventilation in the tadpole to the mature pattern of rhythmic buccal and lung (air) ventilation in the adult. Spatially distinct oscillators drive buccal and lung bursts in the isolated brainstem; we found these oscillators to be active but functionally uncoupled in the tadpole. Over the course of metamorphosis, the rhythms produced by the buccal and lung oscillators become increasingly tightly coordinated. These changes parallel the progression of structural and behavioral changes in the animal, with adult levels of coupling arising by the metamorphic stage (forelimb eruption). These findings suggest that oscillator coupling undergoes a maturation process similar to the refinement of sensory circuits over development.

Diving into the mammalian swamp of respiratory rhythm generation with the bullfrog.

All vertebrates produce some form of respiratory rhythm, whether to pump water over gills or ventilate lungs. Yet despite the critical importance of ventilation for survival, the architecture of the respiratory central pattern generator has not been resolved. In frogs and mammals, there is increasing evidence for multiple burst-generating regions in the ventral respiratory group. These regions work together to produce the respiratory rhythm. However, each region appears to be pivotally important to a different phase of the motor act. Regions also exhibit differing rhythmogenic capabilities when isolated and have different CO2 sensitivity and pharmacological profiles. Interestingly, in both frogs and rats the regions with the most robust rhythmogenic capabilities when isolated are located in rhombomeres 7/8. In addition, rhombomeres 4/5 in both clades are critical for controlling phases of the motor pattern most strongly modulated by CO2 (expiration in mammals, and recruitment of lung bursts in frogs). These key signatures may indicate that these cell clusters arose in a common ancestor at least 400 million years ago.