RESUMO
A crucial evolutionary change in vertebrate history was the Palaeozoic (Devonian 419-359 million years ago) water-to-land transition, allowed by key morphological and physiological modifications including the acquisition of lungs. Nonetheless, the origin and early evolution of vertebrate lungs remain highly controversial, particularly whether the ancestral state was paired or unpaired. Due to the rarity of fossil soft tissue preservation, lung evolution can only be traced based on the extant phylogenetic bracket. Here we investigate, for the first time, lung morphology in extensive developmental series of key living lunged osteichthyans using synchrotron x-ray microtomography and histology. Our results shed light on the primitive state of vertebrate lungs as unpaired, evolving to be truly paired in the lineage towards the tetrapods. The water-to-land transition confronted profound physiological challenges and paired lungs were decisive for increasing the surface area and the pulmonary compliance and volume, especially during the air-breathing on land.
All life on Earth started out under water. However, around 400 million years ago some vertebrates, such as fish, started developing limbs and other characteristics that allowed them to explore life on land. One of the most pivotal features to evolve was the lungs, which gave vertebrates the ability to breathe above water. Most land-living vertebrates, including humans, have two lungs which sit on either side of their chest. The lungs extract oxygen from the atmosphere and transfer it to the bloodstream in exchange for carbon dioxide which then gets exhaled out in to the atmosphere. How this important organ first evolved is a hotly debated topic. This is largely because lung tissue does not preserve well in fossils, making it difficult to trace how the lungs of vertebrates changed over the course of evolution. To overcome this barrier, Cupello et al. compared the lungs of living species which are crucial to understand the early stages of the water-to-land transition. This included four species of lunged bony fish which breathe air at the water surface, and a four-legged salamander that lives on land. Cupello et al. used a range of techniques to examine how the lungs of the bony fish and salamander changed shape during development. The results suggested that the lungs of vertebrates started out as a single organ, which became truly paired later in evolution once vertebrates started developing limbs. This anatomical shift increased the surface area available for exchanging oxygen and carbon dioxide so that vertebrates could breathe more easily on land. These findings provide new insights in to how the lung evolved into the paired structure found in most vertebrates alive today. It likely that this transition allowed vertebrates to fully adapt to breathing above water, which may explain why this event only happened once over the course of evolution.
Assuntos
Evolução Biológica , Água , Animais , Peixes/fisiologia , Fósseis , Pulmão , Filogenia , VertebradosRESUMO
Groups of animals (including humans) may show flexible grouping patterns, in which temporary aggregations or subgroups come together and split, changing composition over short temporal scales, (i.e. fission and fusion). A high degree of fission-fusion dynamics may constrain the regulation of social relationships, introducing uncertainty in interactions between group members. Here we use Shannon's entropy to quantify the predictability of subgroup composition for three species known to differ in the way their subgroups come together and split over time: spider monkeys (Ateles geoffroyi), chimpanzees (Pan troglodytes) and geladas (Theropithecus gelada). We formulate a random expectation of entropy that considers subgroup size variation and sample size, against which the observed entropy in subgroup composition can be compared. Using the theory of set partitioning, we also develop a method to estimate the number of subgroups that the group is likely to be divided into, based on the composition and size of single focal subgroups. Our results indicate that Shannon's entropy and the estimated number of subgroups present at a given time provide quantitative metrics of uncertainty in the social environment (within which social relationships must be regulated) for groups with different degrees of fission-fusion dynamics. These metrics also represent an indirect quantification of the cognitive challenges posed by socially dynamic environments. Overall, our novel methodological approach provides new insight for understanding the evolution of social complexity and the mechanisms to cope with the uncertainty that results from fission-fusion dynamics.
Assuntos
Atelinae/fisiologia , Pan troglodytes/fisiologia , Comportamento Social , Theropithecus/fisiologia , Animais , Comportamento Animal , IncertezaRESUMO
OBJECTIVES: Ketamine offers a plausible mechanism with favorable kinetics in treatment of severe ethanol withdrawal. The purpose of this study is to determine if a treatment guideline using an adjunctive ketamine infusion improves outcomes in patients suffering from severe ethanol withdrawal. DESIGN: Retrospective observational cohort study. SETTING: Academic tertiary care hospital. PATIENTS: Patients admitted to the ICU and diagnosed with delirium tremens by Diagnostic and Statistical Manual of Mental Disorders V criteria. INTERVENTIONS: Pre and post guideline, all patients were treated in a symptom-triggered fashion with benzodiazepines and/or phenobarbital. Postguideline, standard symptom-triggered dosing continued as preguideline, plus, the patient was initiated on an IV ketamine infusion at 0.15-0.3 mg/kg/hr continuously until delirium resolved. Based upon withdrawal severity and degree of agitation, a ketamine bolus (0.3 mg/kg) was provided prior to continuous infusion in some patients. MEASUREMENTS AND MAIN RESULTS: A total of 63 patients were included (29 preguideline; 34 postguideline). Patients treated with ketamine were less likely to be intubated (odds ratio, 0.14; p < 0.01; 95% CI, 0.04-0.49) and had a decreased ICU stay by 2.83 days (95% CI, -5.58 to -0.089; p = 0.043). For ICU days outcome, correlation coefficients were significant for alcohol level and total benzodiazepine dosing. For hospital days outcome, correlation coefficients were significant for patient age, aspartate aminotransferase, and alanine aminotransferase level. Regression revealed the use of ketamine was associated with a nonsignificant decrease in hospital stay by 3.66 days (95% CI, -8.40 to 1.08; p = 0.13). CONCLUSIONS: Mechanistically, adjunctive therapy with ketamine may attenuate the demonstrated neuroexcitatory contribution of N-methyl-D-aspartate receptor stimulation in severe ethanol withdrawal, reduce the need for excessive gamma-aminobutyric acid agonist mediated-sedation, and limit associated morbidity. A ketamine infusion in patients with delirium tremens was associated with reduced gamma-aminobutyric acid agonist requirements, shorter ICU length of stay, lower likelihood of intubation, and a trend toward a shorter hospitalization.
Assuntos
Delirium por Abstinência Alcoólica/tratamento farmacológico , Antagonistas de Aminoácidos Excitatórios/uso terapêutico , Ketamina/uso terapêutico , Centros Médicos Acadêmicos , Adulto , Fatores Etários , Idoso , Benzodiazepinas/administração & dosagem , Quimioterapia Combinada , Antagonistas de Aminoácidos Excitatórios/administração & dosagem , Feminino , Humanos , Hipnóticos e Sedativos/uso terapêutico , Unidades de Terapia Intensiva , Ketamina/administração & dosagem , Tempo de Internação , Testes de Função Hepática , Masculino , Pessoa de Meia-Idade , Estudos Retrospectivos , Índice de Gravidade de DoençaRESUMO
BACKGROUND: Unexpected death of a loved one (UD) is the most commonly reported traumatic experience in cross-national surveys. However, much remains to be learned about posttraumatic stress disorder (PTSD) after this experience. The WHO World Mental Health (WMH) survey initiative provides a unique opportunity to address these issues. METHODS: Data from 19 WMH surveys (n = 78,023; 70.1% weighted response rate) were collated. Potential predictors of PTSD (respondent sociodemographics, characteristics of the death, history of prior trauma exposure, history of prior mental disorders) after a representative sample of UDs were examined using logistic regression. Simulation was used to estimate overall model strength in targeting individuals at highest PTSD risk. RESULTS: PTSD prevalence after UD averaged 5.2% across surveys and did not differ significantly between high-income and low-middle income countries. Significant multivariate predictors included the deceased being a spouse or child, the respondent being female and believing they could have done something to prevent the death, prior trauma exposure, and history of prior mental disorders. The final model was strongly predictive of PTSD, with the 5% of respondents having highest estimated risk including 30.6% of all cases of PTSD. Positive predictive value (i.e., the proportion of high-risk individuals who actually developed PTSD) among the 5% of respondents with highest predicted risk was 25.3%. CONCLUSIONS: The high prevalence and meaningful risk of PTSD make UD a major public health issue. This study provides novel insights into predictors of PTSD after this experience and suggests that screening assessments might be useful in identifying high-risk individuals for preventive interventions.
Assuntos
Atitude Frente a Morte , Morte , Inquéritos Epidemiológicos/estatística & dados numéricos , Acontecimentos que Mudam a Vida , Transtornos de Estresse Pós-Traumáticos/epidemiologia , Transtornos de Estresse Pós-Traumáticos/psicologia , Adolescente , Adulto , Ásia/epidemiologia , Criança , Pré-Escolar , Europa (Continente)/epidemiologia , Feminino , Humanos , Lactente , Modelos Logísticos , Masculino , Prevalência , Risco , Fatores Socioeconômicos , África do Sul/epidemiologia , América do Sul/epidemiologia , Estados Unidos/epidemiologia , Adulto JovemAssuntos
Caudovirales , Classificação , Vírus , Vírus de DNA , Vírus de RNA , Terminologia como AssuntoRESUMO
Jatropha curcas L. has been promoted as an oilseed crop for use to meet the increased world demand for vegetable oil production, and in particular, as a feedstock for biodiesel production. Seed meal is a protein-rich by-product of vegetable oil extraction, which can either be used as an organic fertilizer, or converted to animal feed. However, conversion of J. curcas seed meal into animal feed is complicated by the presence of toxins, though plants producing "edible" or "non-toxic" seeds occur in Mexico. Toxins present in the seeds of J. curcas include phorbol esters and a type-I ribosome inactivating protein (curcin). Although the edible seeds of J. curcas are known to lack phorbol esters, the curcin content of these seeds has not previously been studied. We analyzed the phorbol ester and curcin content of J. curcas seeds obtained from Mexico and Madagascar, and conclude that while phorbol esters are lacking in edible seeds, both types contain curcin. We also analyzed spatial distribution of these toxins in seeds. Phorbol-esters were most concentrated in the tegmen. Curcin was found in both the endosperm and tegmen. We conclude that seed toxicity in J. curcas is likely to be due to a monogenic trait, which may be under maternal control. We also conducted AFLP analysis and conclude that genetic diversity is very limited in the Madagascan collection compared to the Mexican collection.