Baseline and stress-induced steroid plasma levels and immune function vary annually and are associated with vocal activity in male toads (Rhinella icterica).

Theoretical models predict that elevated androgen and glucocorticoid levels in males during the reproductive season promote immunosuppression. However, some studies report decreased stress response during this season. This study investigated annual variation in plasma corticosterone and testosterone levels, plasma bacterial killing ability (BKA), and neutrophil to lymphocyte ratio (NLR) in free-living male toads (Rhinella icterica). Toads were sampled in the field (baseline) and 1 h-post restraint over five months, and we considered the occurrence of vocal activity. Baseline corticosterone, testosterone, and BKA showed higher values during the reproductive period, specifically in calling male toads. The NLR was similar throughout the year, but higher values were observed in calling toads. Moreover, baseline NLR and BKA were positively correlated with both testosterone and corticosterone, suggesting higher steroid levels during reproduction are associated with enhanced cellular and humoral immunity. Despite fluctuation of baseline values, post-restraint corticosterone levels remained uniform over the year, indicating that toads reached similar maximum values throughout the year. Testosterone levels decreased following restraint before one specific reproductive period but increased in response to restraint during and after this period. Meanwhile, BKA decreased due to restraint only after the reproductive period, indicating immune protection and resilience to immunosuppression by stressors associated with steroid hormones during reproduction. Our results show that baseline and stress-induced hormonal and immune regulation varies throughout the year and are associated with vocal activity in R. icterica males, indicating a possible compromise between steroids and immune function in anuran males.

Latin American consensus recommendations on the risk of infections in people with multiple sclerosis treated with disease modifying drugs.

INTRODUCTION: The emergence of several therapeutic options in multiple sclerosis (MS), which significantly modify the immune system functioning, has led to the need for the consideration of additional factors, such as risk of infections, in the decision-making process. The aim of these consensus recommendations was to discuss and perform a practical guide to Latin American neurologists on the risk of infections at diagnosis, follow-up and prior to initiation of DMDs. METHODS: A panel of Latin American neurologists, experts in demyelinating diseases and dedicated to management and care of MS patients, gathered during 2021 and 2022 to make consensus recommendations on the risk of infections in PwMS treated with DMDs in Latin America. The RAND/UCLA methodology was developed to synthesize the scientific evidence and expert opinions on health care topics and was used for reaching a formal agreement. RESULTS: Recommendations were established based on relevant published evidence and expert opinion, focusing on: 1- baseline infection disease and vaccination status; 2- opportunistic infections; 3- progressive multifocal leukoencephalopathy; 4- genitourinary system infections; 5- respiratory tract infections; 6- digestive system infections, 7-others local infections and 8- COVID-19. CONCLUSION: The recommendations of this consensus seek to optimize the care, management and treatment of PwMS in Latin America. The standardized evidence-based care of pwMS infections will allow better outcomes.

Therapeutic strategies in NMOSD and MOGAD patients: A multicenter cohort study in Latin America.

PURPOSE: This study describes the therapeutic strategies in NMOSD and MOGAD adopted by neurologists to treat both conditions in Latin America (LATAM) with main focus on rituximab (RTX) and the disease outcome. METHODS: retrospective study in a cohort of NMOSD and MOGAD patients followed in specialized MS/NMOSD centers from eight countries and 14 LATAM reference centers. Demographics and clinical characteristics were collected. RTX strategies on naïve (for rituximab) patients were summarized as follows: scheme A: two 1000 mg infusions 15 days apart and repeated every 6 months; scheme B: four 375 mg/m2 infusions every week for 4 weeks and repeated every 6 months; scheme C: one 1000 mg infusions and repeated every 6 months; scheme D: other scheme used. Relapse rate and adverse events during follow-up were analyzed considering the different RTX schemes. Poisson and logistic regression analysis were used to assess baseline aspects and disease activity during follow-up. RESULTS: A total of 217 patients were included. 197 were NMOSD patients (164, 83.2% AQP4-IgG seropositive and 16.7% seronegative) and 20 were MOGAD patients. The most frequent long-term treatment was RTX in both groups (48.2% and 65% for NMOSD and MOGAD patients, respectively). The most common RTX regimen used in 79 (83.1%) patients was two 1000 mg infusions 15 days apart and repeat every 6 months. Relapses under RTX treatment were observed in 21 (22.1%) patients. Relapses after RTX treatment were associated with higher EDSS (OR 1.75, 95%CI 1.44-2.34, p = 0.03) and higher ARR pre-RTX (OR = 2.17, 95% CI 1.72-3.12, p = 0.002) but not with RTX regimen (OR = 1.10, 95% CI 0.89-1.21, p = 0.60). CONCLUSION: the most strategy used in LATAM was RTX with two 1000 mg infusions 15 days apart. Relapses during follow up were not associated with RTX regimen used.

Frequency of NMOSD misdiagnosis in a cohort from Latin America: Impact and evaluation of different contributors.

BACKGROUND: Neuromyelitis optica spectrum disorder (NMOSD) misdiagnosis (i.e. the incorrect diagnosis of patients who truly have NMOSD) remains an issue in clinical practice. We determined the frequency and factors associated with NMOSD misdiagnosis in patients evaluated in a cohort from Latin America. METHODS: We retrospectively reviewed the medical records of patients with NMOSD, according to the 2015 diagnostic criteria, from referral clinics in six Latin American countries (Argentina, Chile, Paraguay, Colombia, Ecuador, and Venezuela). Diagnoses prior to NMOSD and ultimate diagnoses, demographic, clinical and paraclinical data, and treatment schemes were evaluated. RESULTS: A total of 469 patients presented with an established diagnosis of NMOSD (73.2% seropositive) and after evaluation, we determined that 56 (12%) patients had been initially misdiagnosed with a disease other than NMOSD. The most frequent alternative diagnoses were multiple sclerosis (MS; 66.1%), clinically isolated syndrome (17.9%), and cerebrovascular disease (3.6%). NMOSD misdiagnosis was determined by MS/NMOSD specialists in 33.9% of cases. An atypical MS syndrome was found in 86% of misdiagnosed patients, 50% had NMOSD red flags in brain and/or spinal magnetic resonance imaging (MRI), and 71.5% were prescribed disease-modifying drugs. CONCLUSIONS: NMOSD misdiagnosis is relatively frequent in Latin America (12%). Misapplication and misinterpretation of clinical and neuroradiological findings are relevant factors associated with misdiagnosis.

Low microbiome diversity in threatened amphibians from two biodiversity hotspots.

Microbial diversity positively influences community resilience of the host microbiome. However, extinction risk factors such as habitat specialization, narrow environmental tolerances, and exposure to anthropogenic disturbance may homogenize host-associated microbial communities critical for stress responses including disease defense. In a dataset containing 43 threatened and 90 non-threatened amphibian species across two biodiversity hotspots (Brazil's Atlantic Forest and Madagascar), we found that threatened host species carried lower skin bacterial diversity, after accounting for key environmental and host factors. The consistency of our findings across continents suggests the broad scale at which low bacteriome diversity may compromise pathogen defenses in species already burdened with the threat of extinction.

Physical constraints on thermoregulation and flight drive morphological evolution in bats.

Body size and shape fundamentally determine organismal energy requirements by modulating heat and mass exchange with the environment and the costs of locomotion, thermoregulation, and maintenance. Ecologists have long used the physical linkage between morphology and energy balance to explain why the body size and shape of many organisms vary across climatic gradients, e.g., why larger endotherms are more common in colder regions. However, few modeling exercises have aimed at investigating this link from first principles. Body size evolution in bats contrasts with the patterns observed in other endotherms, probably because physical constraints on flight limit morphological adaptations. Here, we develop a biophysical model based on heat transfer and aerodynamic principles to investigate energy constraints on morphological evolution in bats. Our biophysical model predicts that the energy costs of thermoregulation and flight, respectively, impose upper and lower limits on the relationship of wing surface area to body mass (S-MR), giving rise to an optimal S-MR at which both energy costs are minimized. A comparative analysis of 278 species of bats supports the model's prediction that S-MR evolves toward an optimal shape and that the strength of selection is higher among species experiencing greater energy demands for thermoregulation in cold climates. Our study suggests that energy costs modulate the mode of morphological evolution in bats­hence shedding light on a long-standing debate over bats' conformity to ecogeographical patterns observed in other mammals­and offers a procedure for investigating complex macroecological patterns from first principles.

Therapeutic plasma exchange for optic neuritis attacks in patients with neuromyelitis optica spectrum disorders.

BACKGROUND: Optic neuritis (ON) causes several sequela. Aggressive treatment with plasma exchange (TPE) is an option. This study describes improvement and safety outcomes with TPE. METHODS: We recruited adults with ON in neuromyelitis optica spectrum disorders (NMOSD) patients treated with TPE. The primary outcome was an improvement in the visual acuity scale (VOS). We described the data and used multivariate logistic regression to identify factors associated with response. RESULTS: Eighty-three patients received 558 TPE sessions. Mean age was 40.9 years (±13.7 years); 73.5% were women, 50.1% were first attack, and 10.7% were bilateral. Median VOS: 5 (range [R], 2-7). Median time between onset and TPE was 8 days (R, 1-32). By Keegan's criteria, 82.4% experience improvement and 78.3% improve in at least 1 point in VOS. Age and pre-TPE VOS were related to improvement. Low fibrinogen occurs in 26% sessions. CONCLUSION: TPE is effective and safety for ON in NMOSD patients. There is a need for a clinical trial using a therapeutic equivalent.

Thermal boldness: Volunteer exploration of extreme temperatures in fruit flies.

A dominant perception is that small and motile ectothermic animals must use behavior to avoid exposure to critical or sub-critical temperatures impairing physiological performance. Concomitantly, volunteer exploration of extreme environments by some individuals may promote physiological adjustments and enhance ecological opportunity. Here we introduce to the literature a Thermal Decision System (TDS) which is fully modular, thermally stable, versatile, and adaptable to study navigation through thermal landscapes in insects and other small motile animals. We used a specific setting of the TDS to investigate volunteer navigation through critical cold and hot temperatures in Drosophila melanogaster. We demonstrate that a thermally bold behavior (volunteer crossings through a Critical Temperature Zone, CTZ) characterized a fraction of flies in a sample, and that such a fraction was higher in an outbred population relative to isofemale lines. As set, the TDS generated a thermal gradient within the cold and hot CTZs, and the exploration of this gradient by flies did not relate simply with a tendency to be thermally bold. Mild fasting affected thermal exploration and boldness in complex manners, but thermal boldness was evident in both fasted and fed flies. Also, thermal boldness was not associated with individual critical temperatures. Finally, some flies showed consistent thermal boldness, as flies that performed an extreme thermal cross were more likely to perform a second cross compared with untested flies. We hypothesize that a simple "avoidance principle" is not the only behavioral drive for D. melanogaster facing extreme temperatures over space, and that this pattern may characterize other small motile ectothermic animals with analogous natural history. The physiological correlates, genetic architecture, and interspecific variation of thermal boldness deserve further consideration.

Seasonal changes in steroid and thyroid hormone content in shed skins of the tegu lizard Salvator merianae.

Sampling blood for endocrine analysis from some species may not be practical or ethical. Quantification of hormones extracted from nontypical sample types, such as keratinized tissues, offers a less invasive alternative to the traditional collection and analysis of blood. Here, we aimed to validate assays by using parallelism and accuracy tests for quantification of testosterone, corticosterone, progesterone, and triiodothyronine (T3) in shed skins of tegu lizards. We assessed whether hormone content of sheds varied across one year similar to what was previously detected in plasma samples. In addition, we aimed to identify the phase relationship between hormone levels of shed skin and plasma levels obtained from the same animals. High frequency of shedding occurred during the active season for tegus (spring/summer), while shedding ceased during hibernation (winter). All hormones measured in shed skins exhibited seasonal changes in concentration. Levels of testosterone in shed skins of male tegus correlated positively with plasma testosterone levels, while corticosterone in both males and females exhibited an inverse relationship between sample types for the same month of collection. An inverse relationship was found when accounting for a lag time of 3 and 4 months between sheds and plasma testosterone. These results indicate that endocrine content of sheds may be confounded by factors (i.e., seasons, environmental temperature, thermoregulatory behavior, among others) that affect frequency of molting, skin blood perfusion, and therefore hormone transfer from the bloodstream and deposition in sheds of squamates.

Metabolic and Redox Biomarkers in Skeletal Muscle Underlie Physiological Adaptations of Two Estivating Anuran Species in a South American Semi-arid Environment.

The upregulation of endogenous antioxidants (i.e., preparation for oxidative stress, POS) is part of the biochemical responses underlying the adaptation of animals to adverse environments. Despite the phylogenetic diversity of animals in which POS has been described, most studies focus on animals under controlled laboratory conditions. To address this limitation, we have recently assessed the redox metabolism in the skeletal muscle of Proceratophrys cristiceps estivating under natural settings in the Caatinga. Here, we analyzed biochemical biomarkers in the muscle of another Caatinga species, Pleurodema diplolister, during the rainy (active) and dry (estivating frogs) seasons. We aimed to determine whether P. diplolister enhances its antioxidants during estivation under field conditions and to identify any effect of species on the biochemical responses of P. diplolister and P. cristiceps associated with estivation. To do so, we measured the activities of representative enzymes of intermediary metabolism and antioxidant systems, as well as glutathione and protein carbonyl levels, in the skeletal muscle of P. diplolister. Our findings revealed the suppression of oxidative metabolism and activation of antioxidant enzymes in estivating P. diplolister compared with active specimens. No changes in oxidative damage to proteins were observed and estivating P. diplolister had lower levels of disulfide glutathione (GSSG) and disulfide-to-total glutathione ratio (GSSG/tGSH) than those observed in active individuals. When data for P. diplolister and P. cristiceps were assembled and analyzed, significant effects of species were detected on the activities of metabolic enzymes (citrate synthase, isocitric dehydrogenase, malic enzyme, and creatine kinase) and antioxidant enzymes (catalase, glutathione peroxidase and glutathione transferase), as well as on GSSG/tGSH ratio. Such effects might underlie the physiological and behavioral differences between these two species that share the same microhabitat and survival strategy (i.e., to estivate) during the dry season. Despite some peculiarities, which reflect the physiological diversity of the mechanisms associated with estivation in the Brazilian Caatinga, both P. diplolister and P. cristiceps seem to balance the suppression of oxidative pathways, the maintenance of the capacity of oxygen-independent pathways, and the activation of endogenous antioxidants to preserve muscle function and be ready to resume activity whenever the unpredictable rainy period arrives.

Fungal infections lead to shifts in thermal tolerance and voluntary exposure to extreme temperatures in both prey and predator insects.

Pathogens can modify many aspects of host behavior or physiology with cascading impacts across trophic levels in terrestrial food webs. These changes include thermal tolerance of hosts, however the effects of fungal infections on thermal tolerances and behavioral responses to extreme temperatures (ET) across trophic levels have rarely been studied. We examined how a fungal pathogen, Beauveria bassiana, affects upper and lower thermal tolerance, and behavior of an herbivorous insect, Acyrthosiphon pisum, and its predator beetle, Hippodamia convergens. We compared changes in thermal tolerance limits (CTMin and CTMax), thermal boldness (voluntary exposure to ET), energetic cost (ATP) posed by each response (thermal tolerance and boldness) between healthy insects and insects infected with two fungal loads. Fungal infection reduced CTMax of both aphids and beetles, as well as CTMin of beetles. Fungal infection modified the tendency, or boldness, of aphids and predator beetles to cross either warm or cold ET zones (ETZ). ATP levels increased with pathogen infection in both insect species, and the highest ATP levels were found in individuals that crossed cold ETZ. Fungal infection narrowed the thermal tolerance range and inhibited thermal boldness behaviors to cross ET. As environmental temperatures rise, response to thermal stress will be asymmetric among members of a food web at different trophic levels, which may have implications for predator-prey interactions, food web structures, and species distributions.

Multiple sclerosis care units in Latin America: Consensus recommendations about its objectives and functioning implementation.

OBJECTIVE: Currently, there are several reasons to promote worldwide the concept of multiple sclerosis care units (MSCU) for a better management of affected patients. Ideally, the MSCU should have some human and technical resources that distinguish and improve the care of affected patients; however, local, and regional aspects should be considered when recommending how these units should operate. The objective of these consensus recommendations was to review how MSCU should work in Latin America to improve long-term outcomes in MS patients. METHODS: A panel of neurology experts from Latin America dedicated to the diagnosis and care of MS patients gathered virtually during 2019 and 2020 to carry out a consensus recommendation about objectives and functioning implementation of MSCU in Latin America. To achieve consensus, the methodology of "formal consensus-RAND/UCLA method" was used. RESULTS: Recommendations focused on the objectives, human and technical resources, and the general functioning that MSCU should have in Latin America. CONCLUSIONS: The recommendations of these consensus guidelines attempt to optimize the health care and management of MS patients by setting how MSCU should work in our region.

Eficacia y seguridad del rituximab en el tratamiento de la esclerosis múltiple: una postura racional en el contexto colombiano / Efficacy and safety of rituximab in the treatment of multiple sclerosis: a rational position in the Colombian context

RESUMEN INTRODUCCIÓN: La esclerosis múltiple es una enfermedad neuroinflamatoria, crónica, degenerativa e incurable, asociada a pérdida neuronal, grados crecientes de discapacidad y deterioro cognoscitivo. Su manejo conlleva grandes costos para los sistemas de salud y la sociedad en general. OBJETIVO: Evaluar la eficacia y la seguridad del uso del rituximab en el manejo de la esclerosis múltiple. MATERIALES Y MÉTODOS: Revisión de la literatura y evaluación de la tecnología en salud tipo mini-HTA en red colaborativa con el Comité de Esclerosis Múltiple de la Asociación Colombiana de Neurología y el Instituto Global de Excelencia Clínica. RESULTADOS: Se identificaron 27 referencias de texto completo para el análisis de la seguridad y la eficacia del rituximab en el manejo de la esclerosis múltiple. Se utilizaron análisis de costos, indicadores epidemiológicos y estudios pivótales de rituximab. CONCLUSIÓN: La evidencia analizada confirma que la terapia con rituximab es efectiva y segura en el manejo de las formas de esclerosis múltiple remitente-recurrente (EMRR) y esclerosis múltiple primaria-progresiva (EMPP), con menor tasa de eventos adversos y tasas de interrupción o abandono del tratamiento más bajas que otras terapias modificadoras de la enfermedad (TME).

SUMMARY INTRODUCTION: Multiple sclerosis is a neuroinflammatory, chronic, degenerative, and incurable disease, associated with neuronal loss, increasing degrees of disability, and cognitive control. Its treatment causes great costs for health systems and society in general. OBJECTIVE: To evaluate the efficacy and safety of the use of rituximab in the management of multiple sclerosis. MATERIALS AND METHODS: Literature review and evaluation of mini-HTA type health technology in a collaborative network with the Multiple Sclerosis Committee of the Colombian Association of Neurology and the Global Institute of Clinical Excellence. RESULTS: 27 full-text references were identified for the safety and efficacy analysis of rituximab in the management of multiple sclerosis. Cost analysis, epidemiological indicators, and pivotal studies of rituximab were incorporated into the analysis. CONCLUSION: The evidence analyzed confirms that rituximab therapy is effective and safe in the management of the forms of Recurrent-Remittent Multiple Sclerosis (RRMS) and Primary-Progressive Multiple Sclerosis (PPMS), with a lower rate of adverse events and discontinuation or withdrawal rates of treatment lower than other disease-modifying therapies.

Tetrodotoxin, a Potential Drug for Neuropathic and Cancer Pain Relief?

Tetrodotoxin (TTX) is a potent neurotoxin found mainly in puffer fish and other marine and terrestrial animals. TTX blocks voltage-gated sodium channels (VGSCs) which are typically classified as TTX-sensitive or TTX-resistant channels. VGSCs play a key role in pain signaling and some TTX-sensitive VGSCs are highly expressed by adult primary sensory neurons. During pathological pain conditions, such as neuropathic pain, upregulation of some TTX-sensitive VGSCs, including the massive re-expression of the embryonic VGSC subtype NaV1.3 in adult primary sensory neurons, contribute to painful hypersensitization. In addition, people with loss-of-function mutations in the VGSC subtype NaV1.7 present congenital insensitive to pain. TTX displays a prominent analgesic effect in several models of neuropathic pain in rodents. According to this promising preclinical evidence, TTX is currently under clinical development for chemo-therapy-induced neuropathic pain and cancer-related pain. This review focuses primarily on the preclinical and clinical evidence that support a potential analgesic role for TTX in these pain states. In addition, we also analyze the main toxic effects that this neurotoxin produces when it is administered at therapeutic doses, and the therapeutic potential to alleviate neuropathic pain of other natural toxins that selectively block TTX-sensitive VGSCs.

Research priorities in multiple sclerosis in Latin America: A multi-stakeholder call to action to improve patients care: Research priorities in MS in LATAM.

As human and economic resources are limited, especially in Latin America (LATAM), it is important to identify research priorities to improve multiple sclerosis (MS) patients care in the region. The objective was to generate a multidisciplinary consensus on research priorities in MS for patients care in LATAM by involving healthcare professionals and MS patient associations. METHODS: consensus was reached through a four-step modified Delphi method designed to identify and rate research priorities in MS in LATAM. The process consisted of two qualitative assessments, a general ranking phase and a consensus meeting followed by a more detailed ranking phase RESULTS: a total of 62 participants (35 neurologists, 4 nurses, 12 kinesiologists, 7 neuropsychologists and 4 patient association members) developed the process. At the final ranking stage following the consensus meeting, each participant provided their final rankings, and the top priority research questions were outlined. 11 research priorities were identified focusing on healthcare access, costs of the disease, physical and cognitive evaluation and rehabilitation, quality of life, symptoms management, prognostic factors, the need of MS care units and patient's management in emergencies like COVID-19. CONCLUSION: this work establishes MS research priorities in LATAM from multiple perspectives. To pursue the actions suggested could launch the drive to obtain information that will help us to better understand the disease in our region and, especially, to better care for affected patients.

Ecological constraints to match field and preferred temperatures in lizards Tropidurus catalanensis (Squamata; Tropiduridae).

We compared microhabitat and body temperatures in the field with thermal preferences of Tropidurus catalanensis to investigate if they match or diverge as demonstration respectively of suitability or poor-quality of the thermal environment. As T. catalanensis is subjected to variable thermal conditions along its distribution and may be jeopardized by the climate change, we measured its thermal preferences after exposure to milder (17 °C-27 °C) and warmer (22 °C-32 °C) thermal conditions to evaluate acclimatory responses and tolerances and vulnerabilities to warming. Field body temperatures tended to be similar to minimum preferred body temperatures, and microhabitat and body temperatures in the field were cooler in the remaining comparisons with thermal preferences [preferred (Tpref), set-point range (Tset), minimum preferred (Tpref_min) and maximum preferred (Tpref_max) body temperatures], suggesting there was a constraint to warming up in nature. The minimum preferred body temperatures may be a threshold separating proper functioning from markedly noxious impacts due to progressive impairment by the cooling. Difficulties to warm and keep suitable body temperatures may jeopardize overall ecophysiological and behavioral processes with implications for maintenance, fitness, and survival. The constraints to warm may impact T. catalanensis differently depending on its body size and its properties of heat conservation (thermal inertia). Smaller and larger T. catalanensis may respectively cool down easier and have difficulties to warm up, being jeopardized by the constraints due to the cold. The warmer preferred body temperatures coupled with the cooler microhabitats and bodies in nature complicate to anticipate how individuals will respond to climate change, but the acclimation to the warmer temperatures led six of them to death, suggesting they had limited tolerance to heat and would be vulnerable to global warming.

Evaluación de riesgo de infecciones e inmunización en pacientes inmunosuprimidos por enfermedad neurológica / Assessment of the risk of infections and immunization in immunosuppressed patients due to neurological disease

RESUMEN La relación entre las enfermedades inmunológicamente mediadas del sistema nervioso central (SNC) y las infecciones es muy estrecha. En primer lugar, es importante reconocer que las infecciones pueden desencadenar reacciones inmunopatológicas que pueden conducir posteriormente a la manifestación de enfermedades neurológicas. En segundo lugar, las infecciones se han reconocido como complicación de algunas de las terapias empleadas para tratar condiciones neurológicas que requieren cierto grado de inmunosupresión. Las estrategias de mitigación de riesgo (EMR) son muy importantes para prevenir complicaciones asociadas con los tratamientos farmacológicos, así como generar estrategias de prevención con respecto a inmunización y detección del perfil de riesgo, antes del inicio de terapias.

SUMMARY The relationship between immunologically mediated diseases of the central nervous system (CNS) and infections is very close. First, it is important to recognize that infections can trigger immunopathological reactions that can subsequently lead to the manifestation of neurological diseases. Second, infections have been recognized as a complication of some of the therapies used to treat neurological conditions that require some degree of immunosuppression. Risk mitigation strategies (RMS) are key in order to prevent complications associated with pharmacological treatments, as well as to generate prevention strategies with respect to immunization and detection of the risk profile, prior to starting therapies.

Comparación entre las secuencias axiales densidad de protones y T2 en lesiones medulares cervicales de pacientes con esclerosis múltiple / Comparison between Axial Sequences of Proton Density and T2 in Cervical Spinal Lesions of Patients with Multiple Sclerosis

Resumen Introducción: Las secuencias ponderaras en T2 con tiempo de eco largo son tradicionalmente usadas para la evaluación de las lesiones de la médula espinal en esclerosis múltiple (EM). Existen otras secuencias, como la densidad de protones (primer eco T2), que pueden ser útiles en el plano axial pero que no se han estudiado lo suficiente. Objetivos Establecer la concordancia entre la densidad de protones (DP) y las secuencias axiales ponderadas en T2 en las lesiones de la médula espinal cervical en pacientes con EM. Métodos: Se trata de un estudio de concordancia entre secuencias DP y T2 axiales en magneto de 1,5 Tesla en sujetos colombianos. Las imágenes fueron revisadas por dos radiólogos, que determinaron el número de lesiones, así como la intensidad de señal - mediante la relación contraste- ruido (RCR). La comparación se realizó con el coeficiente de correlación y concordancia de Lin. Resultados: Se evaluaron 56 pacientes, 30,36% hombres y 69,64% mujeres. Se encontraron diferentes números de lesiones entre las secuencias axiales DP vs T2 (210 vs 144), coeficiente de concordancia entre el número de lesiones 0,72 (IC95%: 0,6-0,82, error estándar 0,05, desviación estándar 1,37) y en la conspicuidad -RCR- 0,62 (IC95%: 0,48-0,75, SE 0,05, DE 12,25). Conclusión: No encontramos concordancia en la evaluación del número o intensidad de la señal entre secuencias axiales DP y T2. Aunque las secuencias ponderadas en T2 son las más utilizadas, investigaciones recientes han demostrado falta de concordancia e incluso superioridad de las secuencias DP en otros planos, lo que sugiere que es necesario realizar estudios para evaluar la efectividad de las secuencias DP en el plano axial.

Abstract Introduction: Traditionally, T2 long echo time sequences are used for the evaluation of spinal cord lesions in multiple sclerosis. There are other sequences, like proton density (first echo of T2) that may be useful in the axial plane but have not been sufficiently studied. Objectives: To establish the agreement between axial PD and T2 sequences in cervical spinal cord lesions in patients with multiple sclerosis. Methods: This is a concordance study between axial PD and T2 sequences in a 1.5 Tesla magnet. The images were reviewed by two radiologists, who determined the number of lesions and signal intensity with the Contrast to Noise Ratio. The comparison was made with the Lin's concordance correlation coefficient. Results: 56 patients were evaluated, 30.36% men and 69.64% women; there were 210 lesions with PD vs 144 with T2, LCC for the number of lesions was 0.72 (95% CI: 0.6-0.82, SE 0.05) and for conspicuity was 0.62 (95% CI: 0.48-0.75, SE 0.05). Conclusion: This study did not find a satisfactory agreement in the evaluation of the number or signal intensity between PD and T2. Recent research has shown superiority of PD over T2 in other planes, suggesting that further studies are needed to evaluate the effectiveness of PD in the axial plane.

Effects of food intake and hydration state on behavioral thermoregulation and locomotor activity in the tropidurid lizard Tropidurus catalanensis.

Theoretical models predict that lizards adjust their body temperature through behavioral thermoregulation as a function of food availability. However, behavioral thermoregulation is also governed by interactions among physiological and ecological factors other than food availability, such as hydration state, and sometimes it can even conflict with the locomotor activity of animals. Here, we aimed to investigate the role of food intake and hydration state on behavioral thermoregulation and voluntary locomotor activity in the lizard Tropidurus catalanensis We hypothesized that food intake can influence behavioral thermoregulation via an interaction with hydration state. We also hypothesized that lizards should endeavor to spend as little time as possible to reach their preferred body temperature to defend other physiological and/or ecological functions. We collected lizards in the field and brought them to the laboratory to measure the preferred temperature selected in a thermal gradient and the total distance traveled by them in fed and unfed conditions and with variable hydration state. Our results showed that food consumption was the most important predictor of preferred temperature. In contrast, either the hydration state alone or its interaction with food consumption did not have important effects on the lizards' thermal preference. Also, we found that the total distance traveled by lizards was not affected by food intake and was barely affected by the hydration state. We provide an experimental approach and a robust analysis of the factors that influence behavioral thermoregulation and locomotor activity in a tropical lizard.