Corticosterone and immune responses to dehydration in squamate reptiles.

Many environments present some degree of seasonal water limitations; organisms that live in such environments must be adapted to survive periods without permanent water access. Often this involves the ability to tolerate dehydration, which can have adverse physiological effects and is typically considered a physiological stressor. While having many functions, the hormone corticosterone (CORT) is often released in response to stressors, yet increasing plasma CORT while dehydrated could be considered maladaptive, especially for species that experience predictable bouts of dehydration and have related coping mechanisms. Elevating CORT could reduce immunocompetence and have other negative physiological effects. Thus, such species likely have CORT and immune responses adapted to experiencing seasonal droughts. We evaluated how dehydration affects CORT and immune function in eight squamate species that naturally experience varied water limitation. We tested whether hydric state affected plasma CORT concentrations and aspects of immunocompetence (lysis, agglutination, bacterial killing ability and white blood cell counts) differently among species based on how seasonally water limited they are and whether this is constrained by phylogeny. The species represented four familial pairs, with one species of each pair inhabiting environments with frequent access to water and one naturally experiencing extended periods (>30 days) with no access to standing water. The effects of dehydration on CORT and immunity varied among species. Increases in CORT were generally not associated with reduced immunocompetence, indicating CORT and immunity might be decoupled in some species. Interspecies variations in responses to dehydration were more clearly grouped by phylogeny than by habitat type.

The evolution of wood warbler flight calls: Species with similar migrations produce acoustically similar calls.

Diverse animal species engage in long-distance migrations. Many migrants travel in groups, and communication within these groups may be important to survival and successful migration. We examined migration and communication in 36 species of wood warblers (Parulidae), songbirds that breed in North America and migrate in mixed-species flocks to their wintering grounds. During migration, wood warblers produce short vocalizations called "flight calls." The function of flight calls and the patterns of acoustic similarity between species are poorly understood. We investigated whether acoustic similarity of flight calls of different species of warbler reflects the similarity in their migratory journeys or their phylogenetic relatedness. We found that phylogeny, similarity in breeding latitude, and overlap in the timing of migration predict acoustic flight call similarity across warbler species. Further, we found that phylogeny, similarity in migration distance, and overlap in wintering range predict acoustic flight call similarity in a subset of 12 species with highly similar calls, although this analysis has a small sample size. We conclude that migratory similarity may be an important force driving the evolution of acoustically similar calls in wood warblers, in addition to phylogenetic relatedness. Acoustic convergence in these species may facilitate communication between individuals with similar migrations.

Sympatry drives colour and song evolution in wood-warblers (Parulidae).

Closely related species often exhibit similarities in appearance and behaviour, yet when related species exist in sympatry, signals may diverge to enhance species recognition. Prior comparative studies provided mixed support for this hypothesis, but the relationship between sympatry and signal divergence is likely nonlinear. Constraints on signal diversity may limit signal divergence, especially when large numbers of species are sympatric. We tested the effect of sympatric overlap on plumage colour and song divergence in wood-warblers (Parulidae), a speciose group with diverse visual and vocal signals. We also tested how number of sympatric species influences signal divergence. Allopatric species pairs had overall greater plumage and song divergence compared to sympatric species pairs. However, among sympatric species pairs, plumage divergence positively related to the degree of sympatric overlap in males and females, while male song bandwidth and syllable rate divergence negatively related to sympatric overlap. In addition, as the number of species in sympatry increased, average signal divergence among sympatric species decreased, which is likely due to constraints on warbler perceptual space and signal diversity. Our findings reveal that sympatry influences signal evolution in warblers, though not always as predicted, and that number of sympatric species can limit sympatry's influence on signal evolution.

Light at night reduces digestive efficiency of developing birds: an experiment with king quail.

Artificial light at night (ALAN) exposes animals to a novel environmental stimulus, one that is generally thought to be maladaptive. ALAN-related health problems have received little attention in non-model species, and we generally know little about the nutritional-physiological impacts of ALAN, especially in young animals. Here, we use a novel application of the acid steatocrit method to experimentally assess changes in digestive efficiency of growing king quail (Excalfactoria chinensis) in response to ALAN. Two weeks after hatching, quail were split into two groups (n = 20-21 per group): overnight-light-treated vs. overnight-dark-treated. When the chicks were 3 weeks old, the experimental group was exposed to weak blue light (ca. 0.3 lux) throughout the entire night for 6 consecutive weeks, until all the chicks had achieved sexual maturation. Fecal samples for assessing digestive efficiency were collected every week. We found that digestive efficiency of quail was reduced by ALAN at two time points from weeks 4 to 9 after hatching (quail reach adulthood by week 9). The negative effect of ALAN on digestion coincided with the period of fastest skeletal growth, which suggests that ALAN may reduce digestive efficiency when energetic demands of growth are at their highest. Interestingly, growth rate was not influenced by ALAN. This suggests that either the negative physiological impacts of ALAN may be concealed when food is provided ad libitum, the observed changes in digestive efficiency were too small to affect growth or condition, or that ALAN-exposed birds had reduced energy expenditure. Our results illustrate that the health impacts of ALAN on wild animals should not be restricted to traditional markers like body mass or growth rate, but instead on a wide array of integrated physiological traits.

Body condition and poxvirus infection predict circulating glucose levels in a colorful songbird that inhabits urban and rural environments.

There is widespread contemporary interest in causes and consequences of blood glucose status in humans (e.g., links to diabetes and cardiovascular disease), but we know comparatively less about what underlies variation in glucose levels of wild animals. Several environmental factors, including diet, disease status, and habitat quality, may regulate glucose circulation, and we are in need of work that assesses many organismal traits simultaneously to understand the plasticity and predictability of glucose levels in ecological and evolutionary contexts. Here, we measured circulating glucose levels in a species of passerine bird (the house finch, Haemorhous mexicanus) that has served as a valuable model for research on sexual selection, disease, and urban behavioral ecology, as these animals display sexually dichromatic ornamental coloration, harbor many infectious diseases (e.g., poxvirus, coccidiosis, mycoplasmal conjunctivitis), and reside in both natural habitats and cities. We tested the effects of sex, habitat type, body condition, coccidiosis and poxvirus infections, and expression of carotenoid plumage coloration on blood glucose concentrations and found that the body condition and poxvirus infection significantly predicted circulating glucose levels. Specifically, birds with higher blood glucose levels had higher body condition scores and were infected with poxvirus. This result is consistent with biomedical, domesticated-animal, and wildlife-rehabilitation findings, and the premise that glucose elevation is a physiological response to or indicator of infection and relative body weight. The fact that we failed to find links between glucose and our other measurements suggests that blood glucose levels can reveal some but not all aspects of organismal or environmental quality.

Interspecific Covariation in Courtship Displays, Iridescent Plumage, Solar Orientation, and Their Interactions in Hummingbirds.

Many animals communicate using multiple signals. Historically, most attention was paid to how multiple signals evolve and function in isolation, but recent work has focused on how they may interact with one another and produce unique signal interaction properties. These interaction properties vary within species, but little is known about how they vary among species, especially in regard to how the expression of particular signals may drive different signal interaction mechanisms. We studied the evolutionary relationships between iridescent plumage, courtship (shuttle) displays, solar environment, and male color appearance during a display (i.e., the signal interaction property) among six species of North American bee hummingbirds. We found that color appearances covary with behavioral and plumage properties, which themselves negatively covary, such that species with more exaggerated displays appeared flashier during courtship, while species with more exaggerated plumage appeared brighter/more colorful with minimal color changes. By understanding how signal interaction properties covary with signals, we were able to discover the complex multilayered evolutionary relationships underlying these traits and uncover new potential drivers of signal evolution. Our results highlight how studying the interaction properties between animal signals provides a richer understanding of how those traits evolved and diversified.

Exposure to artificial light at night increases innate immune activity during development in a precocial bird.

Humans have greatly altered Earth's night-time photic environment via the production of artificial light at night (ALAN; e.g. street lights, car traffic, billboards, lit buildings). ALAN is a problem of growing importance because it may significantly disrupt the seasonal and daily physiological rhythms and behaviors of animals. There has been considerable interest in the impacts of ALAN on health of humans and other animals, but most of this work has centered on adults and we know comparatively little about effects on young animals. We exposed 3-week-old king quail (Excalfactoria chinensis) to a constant overnight blue-light regime for 6 weeks and assessed weekly bactericidal activity of plasma against Escherichia coli - a commonly employed metric of innate immunity in animals. We found that chronic ALAN exposure significantly increased bactericidal activity and that this elevation in immune performance manifested at different developmental time points in males and females. Whether this short-term increase in immune activity can be extended to wild animals, and whether ALAN-mediated increases in immune activity have positive or negative fitness effects, are unknown and will provide interesting avenues for future studies.

Experimental trait mismatches uncover specificity of evolutionary links between multiple signaling traits and their interactions in hummingbirds.

Many animal signals co-occur, and these signals may coevolve due to their interactive properties. Previous work has demonstrated ecological drivers of evolutionary relationships between signals and the environment, which leads to questions about why specific signal pairs evolved among species that possess multiple signals. We asked whether the coloration of different species was optimized for presentation with its natural behavioral display. We investigated this in "bee" hummingbirds, where males exhibit angle-dependent structurally-colored plumage and a stereotyped courtship (shuttle) display, by experimentally creating mismatches between the behavior and plumage of five species and quantifying how these mismatches influenced male color appearance during a display. Specifically, we photographed the plumage from a given species as we moved its feathers through the position-and-orientation-specific courtship display path of other species and quantified the resulting color appearance during the display in order to compare the mismatched color appearance to each species' natural color appearance. We found that mismatches significantly altered display flashiness (% change in coloration during displays) compared to the natural plumage-behavior pairings, and that such departures in flashiness were predicted by differences in shuttle behaviors alone. These results illustrate a tight evolutionary relationship between shuttle displays and color flashiness in these hummingbirds. Further, we found that interspecific variation in male plumage, behavior, and natural color appearance predicted deviations between natural and mismatched flashy color appearance. Altogether, our work provides a new method for testing signal coevolution and highlights the complex evolutionary relationships between multiple signals and their interactions.

It's not just what you have, but how you use it: solar-positional and behavioural effects on hummingbird colour appearance during courtship.

Animals exhibit a diversity of colours that can play key roles in mating interactions. However, we presently lack an understanding of the relative importance of the environment, behaviour and natural reflective properties of colourful ornaments in shaping an individual's colour appearance during mating displays. We investigated interactions among structurally based plumage, display environments and courtship shuttle displays of male Costa's hummingbirds (Calypte costae) to test how these elements may differentially contribute to colour appearance during shuttles. Male position relative to the sun was the strongest predictor of colour appearance, with shuttle behaviours and feather reflectance playing smaller roles. Furthermore, male solar orientation and shuttling behaviour (e.g. shuttle width) were repeatable among displays, whereas male colour appearance mostly was not. These results emphasise the contributions of behaviour and environment to colour-signalling and suggest that relying on reflectance measurements of colourful ornaments alone provides an incomplete picture of ecologically relevant visual phenotypes of displaying animals.

Permanent Paddle-lead Trial for Spinal Cord Stimulation.

Objectives A significant number of chronic pain patients rely on spinal cord stimulation (SCS) for treatment of their intractable pain. A screening trial using percutaneous electrodes is an integral step for predicting a successful treatment course with a permanent SCS system. Most of these trials are performed in an outpatient ambulatory surgical center and some in the office setting. However, there are select patients who are considered poor candidates for percutaneous trials. We present the initial report of patients who have received surgical implantation of permanent paddle-leads for SCS trials at our institution and show that this was a safe and effective alternative for our patients who could not undergo percutaneous trials.  Methods We retrospectively reviewed the hospital charts of 12 patients who underwent permanent surgically-implanted paddle-lead trials from 2014 to 2017. Success was considered positive with a 50% reduction in pain rating. If positive, patients were brought back to the operating room to have the implanted leads connected to an internalized pulse generator.    Results All 12 patients met the criteria for a successful trial. Only one patient had his SCS system surgically removed after nine months. None of our patients reported or returned with paddle-lead migrations or infections.  Conclusions We report that surgically-implanted paddle-lead trials were a safe and effective alternative to percutaneous trials in our patients who were deemed poor candidates for percutaneous trials. No complications occurred and all of our patients received a second surgery for internalization of the SCS system. Patients who have previously failed percutaneous trials may be false-negatives to SCS.

Toxic Myelitis and Arachnoiditis After Intrathecal Delivery of Bupivacaine via an Implanted Drug Delivery System: Case Report and Review of the Literature.

The off-label usage of amino-amide anesthetics in intrathecal drug delivery systems (IDDS) for the treatment of chronic non-malignant and malignant pain is supported in the polyanalgesic consensus guidelines as a second-line adjunctive therapy. Although strong evidence for its clinical efficacy is lacking, its clinical safety profile has been well established within established dosing parameters. Despite the rarity of neurological adverse reactions to intrathecal bupivacaine, whether given as regional anesthesia or intrathecal therapy, neurologic morbidity associated with its administration is well documented. The etiology of adverse reactions is often difficult to definitively identify, especially given the variabilities associated with compounding errors in the formulation, solvent contamination, and mechanical factors. We present a rare case of toxic myelitis and arachnoiditis resulting in paraplegia two months after the addition of bupivacaine to the intrathecal analgesic regimen and discuss possible etiological factors with a review of the literature.

Acute Neuropathic Orchalgia and Scrotalgia After Percutaneous Spinal Cord Stimulator Lead Placement: Two Cases with an Unusual Complication.

Spinal cord stimulation is an effective adjunct to the treatment of a variety of chronic pain syndromes. Complications are relatively low in morbidity and are most often secondary to hardware malfunction/malposition. Infection and undesired dysesthesias represent only a minority of complications. Neuropathic orchalgia and scrotalgia after placement of epidural spinal cord stimulator is a previously unreported morbidity. While alarming, this condition is physiologically benign, causing no neurological or urological dysfunction. The two cases we encountered both occurred during uncomplicated percutaneous trial stimulator placement. Corticosteroid treatment and stimulator activation facilitated resolution of the dysesthesia and allowed completion of the trial in one case, while the other case was refractory and resulted in termination of the trial.

Evolutionary innovation and diversification of carotenoid-based pigmentation in finches.

The ornaments used by animals to mediate social interactions are diverse, and by reconstructing their evolutionary pathways we can gain new insights into the mechanisms underlying ornamental innovation and variability. Here, we examine variation in plumage carotenoids among the true finches (Aves: Fringillidae) using biochemical and comparative phylogenetic analyses to reconstruct the evolutionary history of carotenoid states and evaluate competing models of carotenoid evolution. Our comparative analyses reveal that the most likely ancestor of finches used dietary carotenoids as yellow plumage colorants, and that the ability to metabolically modify dietary carotenoids into more complex pigments arose secondarily once finches began to use modified carotenoids to create red plumage. Following the evolutionary "innovation" that enabled modified red carotenoid pigments to be deposited as plumage colorants, many finch species subsequently modified carotenoid biochemical pathways to create yellow plumage. However, no reversions to dietary carotenoids were observed. The finding that ornaments and their underlying mechanisms may be operating under different selection regimes-where ornamental trait colors undergo frequent reversions (e.g., between red and yellow plumage) while carotenoid metabolization mechanisms are more conserved-supports a growing empirical framework suggesting different evolutionary patterns for ornaments and the mechanistic innovations that facilitate their diversification.

Correction: Lumbosacral Osteomyelitis and Discitis with Phlegmon Following Laparoscopic Sacral Colpopexy.

[This corrects the article DOI: 10.7759/cureus.671.].

Lumbosacral Osteomyelitis and Discitis with Phlegmon Following Laparoscopic Sacral Colpopexy.

Lumbosacral osteomyelitis and discitis are usually a result of hematogenous spread; rarely it can result from direct inoculation during a surgical procedure. Bacteria may also track along implanted devices to a different location. This is a rare complication seen from pelvic organ prolapse surgery with sacral colpopexy. A 67-year-old female developed increasing lower back pain four months following a laparoscopic sacral colpopexy. Imaging revealed lumbar 5-sacral 1 (L5-S1) osteomyelitis and discitis with associated phlegmon confirmed by percutaneous biopsy and culture. The patient was treated conservatively with antibiotics, but required laparoscopic removal of the pelvic and vaginal mesh followed by twelve weeks of intravenous antibiotics. The patient has experienced clinical improvement of her back pain. This is an uncommon complication of sacral colpopexy, but physicians must be vigilant and manage aggressively to avoid more serious complications and permanent deficit.

Migration and the evolution of sexual dichromatism: evolutionary loss of female coloration with migration among wood-warblers.

The mechanisms underlying evolutionary changes in sexual dimorphism have long been of interest to biologists. A striking gradient in sexual dichromatism exists among songbirds in North America, including the wood-warblers (Parulidae): males are generally more colourful than females at northern latitudes, while the sexes are similarly ornamented at lower latitudes. We use phylogenetically controlled comparative analysis to test three non-mutually exclusive hypotheses for the evolution of sexual dichromatism among wood-warblers. The first two hypotheses focus on the loss of female coloration with the evolution of migration, either owing to the costs imposed by visual predators during migration, or owing to the relaxation of selection for female social signalling at higher latitudes. The third hypothesis focuses on whether sexual dichromatism evolved owing to changes in male ornamentation as the strength of sexual selection increases with breeding latitude. To test these hypotheses, we compared sexual dichromatism to three variables: the presence of migration, migration distance, and breeding latitude. We found that the presence of migration and migration distance were both positively correlated with sexual dichromatism, but models including breeding latitude alone were not strongly supported. Ancestral state reconstruction supports the hypothesis that the ancestral wood-warblers were monochromatic, with both colourful males and females. Combined, these results are consistent with the hypotheses that the evolution of migration is associated with the relaxation of selection for social signalling among females and that there are increased predatory costs along longer migratory routes for colourful females. These results suggest that loss of female ornamentation can be a driver of sexual dichromatism and that social or natural selection may be a stronger contributor to variation in dichromatism than sexual selection.

Spinal stimulator peri-electrode masses: case report.

The authors describe a case of delayed spastic quadriparesis caused by a peri-electrode mass following the implantation of a minimally invasive percutaneous spinal cord stimulator (SCS). Prior reports with paddle-type electrodes are reviewed, and a detailed histological and pathophysiological comparison with the present case is made. The patient developed tolerance to a cervical percutaneous SCS 4 months after implantation, followed by the onset of spastic quadriparesis 9 months after implantation. The stimulator was removed, and contrast-enhanced MRI revealed an enhancing epidural mass where the system had been placed, with severe spinal cord compression. Decompression was carried out, and the patient experienced neurological improvement. Pathological examination revealed fibrotic tissue with granulomatous and multinucleated giant cell reactions. No evidence of infection or hemorrhage was found. Professionals treating patients with SCSs or contemplating their insertion should be aware of this delayed complication and associated risk factors.

Neurohistopathological findings at the electrode-tissue interface in long-term deep brain stimulation: systematic literature review, case report, and assessment of stimulation threshold safety.

OBJECTIVES: Despite the widespread use of deep brain stimulation (DBS) in the treatment of neurologic disorders for over a quarter of a century, there has not been a systematic review and analyses of cases in which long-term postmortem clinic-pathologic data have been collected demonstrating the effects of chronically implanted electrodes and electrical stimulation on human brain tissue. Our objective is to provide a comprehensive systematic review of the literature on clinicopathologic findings of DBS tissue-electrode interface (TEI) and to determine types and prevalences of neuropathological findings among electrode materials and stimulation parameters and to augment this with previously unpublished histopathological data, images, and analyses from a DBS case implanted for 12 years, providing the longest duration histopathological follow-up. MATERIALS AND METHODS: A Medline literature review identified DBS cases upon which postmortem clinicopathologic follow-up was performed with adequate characterization of TEI. Direct follow-up with authors augmented this with unpublished data and neuropathological details. RESULTS: We identified 40 cases, mean age 59.1 ± 13.0 (range: 21-88) years, involving 58 implanted DBS electrodes. The mean postmortem histopathological follow-up of the implanted DBS electrodes was 22.2 ± 29.2 (range: 0.067-146) months, including our case with a 12-year follow-up. The following histological changes were identified: fibrous sheaths (5-25 µm thickness) surrounding the electrode (94%), fibrillary gliosis (73%), reactive astrocytes (78%), multinucleated giant cells (75%), mononuclear leukocytes (92%), and macrophages (91%). Microglial activation (60%), axonal spheroids (64%), and neuronal loss (60%) were less common and absent at 12-year follow-up in the index case. This is seventh case reporting T cell presence at the TEI. CONCLUSIONS: Neuropathological findings from published cases and our 12-year follow-up index case confirm the long-term safety of neuromodulation and stimulation thresholds and demonstrate persistence of T cells and occasional subclinical focal tissue injury.

Risks of common complications in deep brain stimulation surgery: management and avoidance.

OBJECT: Deep brain stimulation (DBS) surgery is increasingly prominent in the treatment of various disorders refractory to medication. Despite the procedure's efficacy, the community at large continues to be hesitant about presumed associated risks. The main object of this study was to assess the incidence of various surgical complications occurring both during and after DBS device implantation in a large population of patients with movement disorders in an effort to better quantify patient risk, define management plans, and develop methods for risk avoidance. A second aim was to corroborate the low procedural complication risk of DBS reported by others, which in light of the procedure's efficacy is needed to promote its widespread acceptance. METHODS: All patients who had undergone new DBS device implantation surgery between 2002 and 2010 by a single surgeon were entered into a database after being verified by cross-referencing manufacturer implantation records. All surgical records and charts were reviewed to identify intraoperative, perioperative, and long-term surgical complications, including any characteristics predictive of an adverse event. RESULTS: Seven hundred twenty-eight patients received 1333 new DBS electrodes and 1218 new internal pulse generators (IPGs) in a total of 1356 stereotactic procedures for the treatment of movement disorders. Seventy-eight percent of the patients had staged lead and IPG implantations. Of the 728 patients, 452 suffered from medically refractory Parkinson disease; in the other patients, essential tremor (144), dystonia (64), mixed disease (30), and other hyperkinetic movement disorders (38) were diagnosed. Severe intraoperative adverse events included vasovagal response in 6 patients (0.8%), hypotension in 2 (0.3%), and seizure in 2 (0.3%). Postoperative imaging confirmed asymptomatic intracerebral hemorrhage (ICH) in 4 patients (0.5%), asymptomatic intraventricular hemorrhage in 25 (3.4%), symptomatic ICH in 8 (1.1%), and ischemic infarction in 3 (0.4%), associated with hemiparesis and/or decreased consciousness in 13 (1.7%). Long-term complications of DBS device implantation not requiring additional surgery included hardware discomfort in 8 patients (1.1%) and loss of desired effect in 10 (1.4%). Hardware-related complications requiring surgical revision included wound infections in 13 patients (1.7%), lead malposition and/or migration in 13 (1.7%), component fracture in 10 (1.4%), component malfunction in 4 (0.5%), and loss of effect in 19 (2.6%). CONCLUSIONS: The authors confirmed that the overall risk of both procedure- and hardware-related adverse events is acceptably low. They offer advice on how to avoid the most common complications.