The chromatophores of cephalopods differ fundamentally from those of other animals: they are neuromuscular organs rather than cells and are not controlled hormonally. They constitute a unique motor ...system that operates upon the environment without applying any force to it. Each chromatophore organ comprises an elastic sacculus containing pigment, to which is attached a set of obliquely striated radial muscles, each with its nerves and glia. When excited the muscles contract, expanding the chromatophore; when they relax, energy stored in the elastic sacculus retracts it. The physiology and pharmacology of the chromatophore nerves and muscles of loliginid squids are discussed in detail. Attention is drawn to the multiple innervation of dorsal mantle chromatophores, of crucial importance in pattern generation. The size and density of the chromatophores varies according to habit and lifestyle. Differently coloured chromatophores are distributed precisely with respect to each other, and to reflecting structures beneath them. Some of the rules for establishing this exact arrangement have been elucidated by ontogenetic studies. The chromatophores are not innervated uniformly: specific nerve fibres innervate groups of chromatophores within the fixed, morphological array, producing ‘physiological units’ expressed as visible ‘chromatomotor fields’. The chromatophores are controlled by a set of lobes in the brain organized hierarchically. At the highest level, the optic lobes, acting largely on visual information, select specific motor programmes (i.e. body patterns); at the lowest level, motoneurons in the chromatophore lobes execute the programmes, their activity or inactivity producing the patterning seen in the skin. In Octopus vulgaris there are over half a million neurons in the chromatophore lobes, and receptors for all the classical neurotransmitters are present, different transmitters being used to activate (or inhibit) the different colour classes of chromatophore motoneurons. A detailed understanding of the way in which the brain controls body patterning still eludes us: the entire system apparently operates without feedback, visual or proprioceptive. The gross appearance of a cephalopod is termed its body pattern. This comprises a number of components, made up of several units, which in turn contains many elements: the chromatophores themselves and also reflecting cells and skin muscles. Neural control of the chromatophores enables a cephalopod to change its appearance almost instantaneously, a key feature in some escape behaviours and during agonistic signalling. Equally important, it also enables them to generate the discrete patterns so essential for camouflage or for signalling. The primary function of the chromatophores is camouflage. They are used to match the brightness of the background and to produce components that help the animal achieve general resemblance to the substrate or break up the body's outline. Because the chromatophores are neurally controlled an individual can, at any moment, select and exhibit one particular body pattern out of many. Such rapid neural polymorphism (‘polyphenism’) may hinder search-image formation by predators. Another function of the chromatophores is communication. Intraspecific signalling is well documented in several inshore species, and interspecific signalling, using ancient, highly conserved patterns, is also widespread. Neurally controlled chromatophores lend themselves supremely well to communication, allowing rapid, finely graded and bilateral signalling.
Diabetic retinopathy (DR) is the leading cause of blindness in the working-age population in the U.S. The vision-threatening processes of neuroglial and vascular dysfunction in DR occur in concert, ...driven by hyperglycemia and propelled by a pathway of inflammation, ischemia, vasodegeneration, and breakdown of the blood retinal barrier. Currently, no therapies exist for normalizing the vasculature in DR. Here, we show that a single intravitreal dose of adeno-associated virus serotype 2 encoding a more stable, soluble, and potent form of angiopoietin 1 (AAV2.COMP-Ang1) can ameliorate the structural and functional hallmarks of DR in Ins2Akita mice, with sustained effects observed through six months. In early DR, AAV2.COMP-Ang1 restored leukocyte-endothelial interaction, retinal oxygenation, vascular density, vascular marker expression, vessel permeability, retinal thickness, inner retinal cellularity, and retinal neurophysiological response to levels comparable with nondiabetic controls. In late DR, AAV2.COMP-Ang1 enhanced the therapeutic benefit of intravitreally delivered endothelial colony-forming cells by promoting their integration into the vasculature and thereby stemming further visual decline. AAV2.COMP-Ang1 single-dose gene therapy can prevent neurovascular pathology, support vascular regeneration, and stabilize vision in DR.
An investigation of the production of C2H4 through the selective dehydrogenation of C2H6 in short contact time reactors featuring a ceramic-foam catalyst coated with platinum is reported. The surface ...chemistry was derived on the basis of four reaction classes (direct adsorption, adsorption on an adsorbate, surface reactions with adsorbed reactants and unimolecular surface reactions including desorption) using collision theory with energy barriers obtained from DFT studies and the UBI–QEP method. The derived mechanism accounts for differences in site occupation and surface bonding types and includes 35 adsorbed chemical species and 283 reversible reactions. The study also features a comprehensively validated C1–C2 mechanism for the gas phase consisting of 44 chemical species and 271 reversible reactions. The complete chemistry was evaluated through extensive sensitivity analysis with reference to 16 sets of new experimental data. The reaction dynamics were studied using inlet velocities in the range 1.34 to 6.72 m/s and the impact on selectivities of variations in the oxygen to carbon weight ratio between 0.45 and 0.75 assessed. It is shown that the simulations capture all experimental trends with reasonable quantitative accuracy. The study suggests that the catalytic dehydrogenation of C2H6 initially contributes to the net production of C2H4 and that changing conditions in the gas phase adjacent to the catalyst can result in the consumption of ethylene principally leading to methane and carbon deposition. It is shown that the consumption of H2 and O2 proceeds predominantly through catalytic conversion under all conditions and that OH(s) provides a dominant channel for the removal of surface carbon. It is also shown that the consumption of oxygenated species features surface specific channels.
We present a new technique for the sutureless closure of corneal incisions after intrastromal corneal ring segment (ICRS) insertion. Twelve eyes of 7 patients with keratoconus were treated at our ...institution by the same surgeon with femtosecond laser–assisted ICRS implantation followed by slit-incision closure with a hydrogel ocular sealant. A retrospective review of clinical characteristics was performed over a mean follow-up of 5 months and compared with previously published data on traditional methods for wound management after ICRS insertion. All visual, refractive, and topographic outcomes were within expected limits. No adverse events were observed. Hydrogel ocular sealant was deemed to be a safe, effective, and surgeon-friendly option for wound closure during ICRS implantation. Financial Disclosure None of the authors has a financial or proprietary interest in any material or method mentioned.
Purpose
To describe clinical outcomes of secondary intraocular lens (IOL) implantation using sutureless trans-scleral techniques in surgically complex eyes.
Methods
Retrospective surgical case series ...of 45 eyes that underwent secondary IOL implantation using a sutureless haptic flange technique. Demographic data of age, sex, primary diagnosis, best-corrected visual acuity (BCVA), refractive error, intraocular pressure, full ophthalmic exam findings, surgical approach, and any intraoperative complications were noted.
Results
The most common indication for secondary IOL implantation was aphakia, most commonly after ocular trauma. The primary outcome measures were pre-operative and post-operative BCVA, which revealed recovery of pre-operative vision levels by post-operative week 1 and improved vision by post-operative month 1 (
p
= 0.03). Secondary outcome measures of target refraction pre-operatively and post-operatively revealed significant reduction in post-operative spherical equivalent to achieve BCVA (
p
< 0.001). Targeting of the secondary IOLs using Barrett Universal II, Holladay 1, Holladay 2, and SRK/T all exhibited a hyperopic shift post-operatively in post-traumatic aphakic eyes and a myopic shift in the post complicated cataract extraction eyes. No intraoperative adverse events were noted. The most common post-operative complication was transient IOP elevation, with most patients completing 6 months of follow-up.
Conclusion
There is rapid visual rehabilitation and reduction of spherical equivalent correction to attain BCVA in eyes with a history of ocular trauma that undergo secondary IOL implantation using a trans-scleral flange technique. Moreover, this study highlights that a specific IOL power formula can be more predictive of the desired refractive outcome depending on the indication for secondary IOL implantation.
To evaluate the clinical, anatomic and functional effects of conversion to aflibercept following ranibizumab and/or bevacizumab in patients with neovascular age-related macular degeneration (AMD).
A ...retrospective review of patients with neovascular AMD treated with intravitreal ranibizumab and/or bevacizumab who were switched to aflibercept was performed. The primary outcome was change in injection frequency in the year following the change. Secondary outcomes included change in central macular thickness (CMT) at 6 months and 1 year, presence of intraretinal and subretinal fluid at 6 months and visual acuity at 1 year.
A total of 109 eyes with neovascular AMD were switched to aflibercept and met inclusion criteria. Overall, aflibercept injection frequency was unchanged with patients receiving 7.4 antivascular endothelial growth factor (VEGF) injections the year prior to conversion compared with 7.2 aflibercept injections in the year following (p=0.47). However, the change to aflibercept was associated with improvement in CMT from 324 to 295 μm (p=0.0001) at 6 months and 299 μm (p=0.0047) at 1 year. There was no effect on visual acuity at 1 year. In a subgroup analysis, patients who had received ≥10 anti-VEGF injections in the year prior had fewer injections (11.1 to 8.4, p<0.0001) and clinic visits (13.9 to 9.6, p<0.0001) as well as a significant decrease in CMT (-35 μm, p=0.02).
In our population, switching to aflibercept therapy was not associated with a change in injection frequency nor improved visual acuity, but was associated with improved CMT at 6 months and 1 year. In patients who received at least 10 anti-VEGF injections in the year prior, transitioning to aflibercept was associated with a reduced injection frequency and CMT, suggesting potential cost savings in this population.
Diabetic macular edema (DME) remains one of the leading causes of moderate to severe vision loss. Although laser photocoagulation was the standard of care for several years, few patients achieved ...significant improvements in visual acuity. As a result, several pharmacotherapies and surgeries have been investigated. The fluocinolone acetonide devices are one of the latest therapies considered for the treatment of DME. Despite bringing significant improvements in visual acuity, fluocinolone devices are associated with cataract formation, increased intraocular pressure (IOP), and surgery to lower IOP. Due to the risk of complications, fluocinolone acetonide devices should be considered only in cases refractive to first-line therapies. In this review, we evaluate current and emerging therapies for DME, with special emphasis on fluocinolone acetonide intravitreal devices.
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