RESUMO
Ochratoxin A (OTA) is considered one of the main mycotoxins responsible for health problems and considerable economic losses in the feed industry. The aim was to study OTA's detoxifying potential of commercial protease enzymes: (i) Ananas comosus bromelain cysteine-protease, (ii) bovine trypsin serine-protease and (iii) Bacillus subtilis neutral metalloendopeptidase. In silico studies were performed with reference ligands and T-2 toxin as control, and in vitro experiments. In silico study results showed that tested toxins interacted near the catalytic triad, similar to how the reference ligands behave in all tested proteases. Likewise, based on the proximity of the amino acids in the most stable poses, the chemical reaction mechanisms for the transformation of OTA were proposed. In vitro experiments showed that while bromelain reduced OTA's concentration in 7.64% at pH 4.6; trypsin at 10.69% and the neutral metalloendopeptidase in 8.2%, 14.44%, 45.26% at pH 4.6, 5 and 7, respectively (p < 0.05). The less harmful α-ochratoxin was confirmed with trypsin and the metalloendopeptidase. This study is the first attempt to demonstrate that: (i) bromelain and trypsin can hydrolyse OTA in acidic pH conditions with low efficiency and (ii) the metalloendopeptidase was an effective OTA bio-detoxifier. This study confirmed α-ochratoxin as a final product of the enzymatic reactions in real-time practical information on OTA degradation rate, since in vitro experiments simulated the time that food spends in poultry intestines, as well as their natural pH and temperature conditions.
Assuntos
Micotoxinas , Ocratoxinas , Animais , Bovinos , Ocratoxinas/análise , Bromelaínas , Simulação de Acoplamento Molecular , Tripsina , Ração Animal/análise , MetaloendopeptidasesRESUMO
BACKGROUND: Adenocarcinoma is preceded by chronic atrophic gastritis, gastric intestinal metaplasia and dysplasia. Trefoil factor 3 (TFF3) is a peptide secreted by goblet cells, which is abundantly present in intestinal metaplasia. AIM: To evaluate the utility of serum TFF3 as a non-invasive biomarker for the diagnosis of intestinal metaplasia and gastric cancer. METHODS: Single-center, cross-sectional study of 274 patients who consecutively underwent upper gastrointestinal endoscopy with gastric biopsies (updated Sydney system). TFF3 levels were measured in serum by a commercial ELISA kit. Patients with normal histology or chronic atrophic gastritis without intestinal metaplasia comprised the control group. In addition, 14 patients with invasive gastric cancer were included as a reference group. The association between TFF3 levels and intestinal metaplasia was assessed by logistic regression. RESULTS: Patients with intestinal metaplasia (n=110) had a higher median TFF3 level as compared to controls (n=164), 13.1 vs. 11.9ng/mL, respectively (p=0.024). Multivariable logistic regression showed a no significant association between TFF3 levels and intestinal metaplasia (OR=1.20; 95%CI: 0.87-1.65; p-trend=0.273). The gastric cancer group had a median TFF3 level of 20.5ng/mL, and a significant association was found (OR=3.26; 95%CI: 1.29-8.27; p-trend=0.013). CONCLUSION: Serum levels of TFF3 do not discriminate intestinal metaplasia in this high-risk Latin American population. Nevertheless, we confirmed an association between TFF3 levels and invasive gastric cancer.
Assuntos
Gastrite Atrófica , Helicobacter pylori , Lesões Pré-Cancerosas , Neoplasias Gástricas , Humanos , Neoplasias Gástricas/patologia , Fator Trefoil-3 , Estudos Transversais , Biomarcadores , Metaplasia/patologia , Mucosa Gástrica , Lesões Pré-Cancerosas/patologiaRESUMO
Introducción: Las endoprótesis son el método de elección para la reconstrucción luego de las resecciones oncológicas. Los avances en los materiales y diseños permitieron expandir las indicaciones a enfermedades no neoplásicas. Su montaje intraoperatorio simple y rápido, y su estabilidad mecánica inmediata permiten una rehabilitación y una recuperación funcional tempranas. Sin embargo, la tasa de fallas es elevada, aunque distinta de la de las enfermedades oncológicas. Las causas predominantes son diferentes. Objetivos: Analizar nuestra experiencia con el uso de endoprótesis de rodilla y compararla con los estudios publicados, evaluando los resultados funcional y radiográfico, la supervivencia del implante y las causas de su eventual falla. Materiales y Métodos: Se seleccionaron pacientes con enfermedad no neoplásica compleja de rodilla que requirieran una reconstrucción con endoprótesis. Para el examen clínico y la evaluación funcional se utilizó el puntaje de la Musculoskeletal Tumor Society, y para las fallas de los implantes, la clasificación de Henderson y cols. modificada. Resultados:Se estudiaron 12 endoprótesis, con un seguimiento promedio de 3.8 años. Se registraron 2 fallas (18%), con un tiempo promedio hasta la falla de 47.5 meses. Una fue tipo 2 (aflojamiento aséptico) y la otra, tipo 4 (infección). No hubo otras complicaciones. En la evaluación funcional, el puntaje final medio fue del 76,6%. Conclusión: Nuestros resultados respaldan el uso de endoprótesis para enfermedades complejas no neoplásicas de rodilla en pacientes cuidadosamente seleccionados, pese a ser un procedimiento quirúrgico complejo y con muchas complicaciones. Nivel de Evidencia: IV
Introduction: Endoprosthesis is the gold standard for reconstruction after oncological resections. The advances regarding its materials and designs allowed for the expansion of the indications to non-neoplastic pathologies. Its simple and fast intraoperative assembly and its immediate mechanical stability allow for early rehabilitation and functional recovery. However, the failure rate is high, although it is different from oncological pathologies. The predominant causes are varied. Objectives: To analyze our experience in the use of knee endoprosthesis and compare it with the literature, evaluating functional outcomes, radiographic outcomes, implant survival and causes of eventual failure. Materials and Methods: Patients with complex non-neoplastic knee pathology that required reconstruction with endoprosthesis were selected. Clinical history, anamnesis, physical examination, and radiographs were reviewed. For clinical examination and functional evaluation, the MusculoSkeletal Tumor Society Score (MSTS Score) was used. For implant failures, the modified Henderson et al. classification was used. Results: 12 endoprostheses were studied, with an average follow-up of 3.8 years. Failures were recorded in 2 (18%), with a mean time to failure of 47.5 months. One type 2 failure (aseptic loosening) and one type 4 failure (infection) were recorded. No other complications were noted. For the functional evaluation, the mean final score was 76.6%. Conclusion: Our results support the use of endoprostheses for complex non-neoplastic knee diseases in carefully selected patients, despite being a complex surgical procedure with many complications.Keywords: Endoprosthesis; knee; infection; complications. Level of Evidence: IV
Assuntos
Adulto , Pessoa de Meia-Idade , Idoso , Complicações Pós-Operatórias , Próteses e Implantes , Seguimentos , Resultado do Tratamento , Artroplastia do JoelhoRESUMO
Biomonitoring is a valuable tool for assessing the presence and effects of air pollutants such as heavy metals (HM); due to their toxicity and stability, these compounds can affect human health and the balance of ecosystems. To assess its potential as a sentinel organism of HM pollution, the wild plant Gnaphalium lavandulifolium was exposed to four sites in the metropolitan area of México Valley (MAMV): Altzomoni (ALT) Coyoacán (COY), Ecatepec (ECA), and Tlalnepantla (TLA) during 2, 4, and 8 weeks, between October and November 2019. Control plants remained under controlled conditions. The chemical analysis determined twelve HM (Al, As, Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, V, and Zn) in the leaves. Macroscopic damage to the leaves, later determined in semi-thin sections under light microscopy, lead to a finer analysis. Transmission electron microscope (TEM) showed major structural changes: chromatin condensation, protoplast shrinkage, cytoplasm vacuolization, cell wall thinning, decreased number and size of starch grains, and plastoglobules in chloroplasts. All these characteristics of stress-induced programed cell death (sPCD) were related to the significant increase of toxic HM in the leaves of the exposed plants compared to the control (p < 0.05). Immunohistochemistry revealed a significant amount of proteases with caspase 3-like activity in ECA and TLA samples during long exposure times. Ultrastructural changes and sPCD features detected confirmed the usefulness of G. lavandulifolium as a good biomonitor of HM contamination. They supported the possibility of considering subcellular changes as markers of abiotic stress conditions in plants.
Assuntos
Gnaphalium , Metais Pesados , Humanos , Monitoramento Biológico , Monitoramento Ambiental , Ecossistema , México , Metais Pesados/toxicidade , Metais Pesados/análiseRESUMO
Mammalian torpor is a phenotype characterized by a controlled decline of metabolic rate, generally followed by a reduction in body temperature. During arousal from torpor, both metabolic rate and body temperature rapidly returns to resting levels. Metabolic rate reduction experienced by torpid animals is triggered by active suppression of mitochondrial respiration, which is rapidly reversed during rewarming process. In this study, we analyzed the changes in the maximal activity of key enzymes related to electron transport system (complexes I, III and IV) in six tissues of torpid, arousing and euthermic Chilean mouse-opossums (Thylamys elegans). We observed higher maximal activities of complexes I and IV during torpor in brain, heart and liver, the most metabolically active organs in mammals. On the contrary, higher enzymatic activities of complexes III were observed during torpor in kidneys and lungs. Moreover, skeletal muscle was the only tissue without significant differences among stages in all complexes evaluated, suggesting no modulation of oxidative capacities of electron transport system components in this thermogenic tissue. In overall, our data suggest that complexes I and IV activity plays a major role in initiation and maintenance of metabolic suppression during torpor in Chilean mouse-opossum, whereas improvement of oxidative capacities in complex III might be critical to sustain metabolic machinery in organs that remains metabolically active during torpor.
Assuntos
Complexo III da Cadeia de Transporte de Elétrons/metabolismo , Complexo IV da Cadeia de Transporte de Elétrons/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , Mitocôndrias/metabolismo , Gambás/fisiologia , Fenótipo , Torpor/fisiologia , Animais , Nível de Alerta , Temperatura Corporal , Encéfalo/enzimologia , Transporte de Elétrons , Rim/enzimologia , Fígado/enzimologia , Pulmão/enzimologia , Músculo Esquelético/enzimologia , Miocárdio/enzimologia , OxirreduçãoRESUMO
Furan is a possible human carcinogen, which is formed in worldwide highly consumed fried starchy foods. In order to elucidate the mechanisms responsible for its occurrence in this food category and propose techniques for its mitigation, the kinetics of furan formation, oil absorption, lipid oxidation, and color change were studied in wheat flour-based model systems during frying at 160, 170, 180, and 190 °C up to 13 min and data were fitted to mathematical models. Additionally, an Arrhenius-type dependency with temperature was evaluated for all studied responses. More drastic frying conditions increased significantly (P ≤ 0.05) the furan content of fried samples. Furan formation followed a sigmoid trend with frying time only for frying temperature of 190 °C (RMS190°C : 7.6%). At lower temperatures, furan generation did not reach the asymptotic concentration level. Color change, lipid oxidation, and oil absorption increased with frying temperature and followed asymptotic relationships with frying time. For all evaluated temperatures, color change (RMS: 4.4% to 12.5%) and polar compound generation (RMS: 2.6% to 7.4%) presented good fit to a first-order kinetic model. Oil absorption was successfully fit to a mass balance-based model (RMS: 10.0% to 19.8%). Under the experimental conditions studied, only color change (EA : 15.47 kJ/mol), lipid oxidation (EA : 6.67 kJ/mol), and oil absorption (EA : 76.98 kJ/mol) presented good fit (RMS: 0.7% to 6.3%) to an Arrhenius-type equation. Based on our results, the keeping of frying temperature below 180 °C and the reduction of the frying time would contribute to reduce not only the final furan occurrence in fried foods but also their oil content.
Assuntos
Culinária/métodos , Grão Comestível/química , Farinha/análise , Furanos/química , Temperatura Alta , Triticum/química , Humanos , Cinética , Modelos Biológicos , OxirreduçãoRESUMO
Biological invasions are recognized as an important biotic component of global change that threatens the composition, structure and functioning of ecosystems, resulting in loss of biodiversity and displacement of native species. Although ecological characteristics facilitating the establishment and spread of non-native species are widely recognized, little is known about organismal attributes underlying invasion success. In this study, we tested the effect of thermal acclimation on thermal tolerance and locomotor performance in the invasive Xenopus laevis and the Chilean native Calyptocephalella gayi. In particular, the maximal righting performance (µMAX), optimal temperature (TO), lower (CTmin) and upper critical thermal limits (CTmax), thermal breadth (Tbr) and the area under the performance curve (AUC) were studied after 6 weeks acclimation to 10 and 20°C. We observed higher values of µmax and AUC in X. laevis in comparison to C. gayi. On the contrary, the invasive species showed lower values of CTmin in comparison to the native one. In contrast, CTmax, TO and Tbr showed no inter-specific differences. Moreover, we found that both species have the ability to acclimate their locomotor performance and lower thermal tolerance limit at low temperatures. Our results demonstrate that X. laevis is a better performer than C. gayi. Although there were differences in CTmin, the invasive and native frogs did not differ in their thermal tolerance. Interestingly, in both species the lower and upper critical thermal limits are beyond the minimal and maximal temperatures encountered in nature during the coldest and hottest month, respectively. Overall, our findings suggest that both X. laevis and C. gayi would be resilient to climate warming expectations in Chile.
RESUMO
Torpor is a phenotype characterized by a controlled decline of metabolic rate and body temperature. During arousal from torpor, organs undergo rapid metabolic reactivation and rewarming to near normal levels. As torpor progress, animals show a preference for fatty acids over glucose as primary source of energy. Here, we analyzed for first time the changes in the maximal activity of key enzymes related to fatty acid (Carnitine palmitoyltransferase and ß-Hydroxyacyl CoA dehydrogenase) and carbohydrate (Pyruvate kinase, Phosphofructokinase and Lactate dehydrogenase) catabolism, as well as mitochondrial oxidative capacity (Citrate synthase), in six organs of torpid, arousing and euthermic Chilean mouse-opossums (Thylamys elegans). Our results showed that activity of enzymes related to fatty acid and carbohydrate catabolism were different among torpor phases and the pattern of variation differs among tissues. In terms of lipid utilization, maximal enzymatic activities differ in tissues with high oxidative capacity such as heart, kidney, and liver. In terms of carbohydrate use, lower enzymatic activities were observed during torpor in brain and liver. Interestingly, citrate synthase activity did not differ thought torpor-arousal cycle in any tissues analyzed, suggesting no modulation of mitochondrial content in T. elegans. Overall results provide an indication that modulation of enzymes associated with carbohydrate and fatty-acid pathways is mainly oriented to limit energy expensive processes and sustain energy metabolism during transition from torpor to euthermy. Future studies are required to elucidate if physiological events observed for T. elegans are unique from other marsupials, or represents a general response in marsupials. J. Exp. Zool. 325A:41-51, 2016. © 2015 Wiley Periodicals, Inc.
Assuntos
Metabolismo Energético/genética , Marsupiais/metabolismo , Mitocôndrias/metabolismo , Gambás/genética , 3-Hidroxiacil-CoA Desidrogenases/metabolismo , Animais , Carnitina O-Palmitoiltransferase/metabolismo , Citrato (si)-Sintase/metabolismo , L-Lactato Desidrogenase/metabolismo , Marsupiais/genética , Mitocôndrias/enzimologia , Mitocôndrias/genética , Gambás/metabolismo , Piruvato Quinase/metabolismo , Torpor/genética , Torpor/fisiologiaRESUMO
Resident passerines inhabiting high latitude environments are faced with strong seasonal changes in thermal conditions and energy availability. Summit metabolic rate (maximal metabolic rate elicited by shivering during cold exposure: M(sum)) and basal metabolic rate (BMR) vary in parallel among seasons and increase in winter due to cold acclimatization, and these adjustments are thought to be critical for survival. Wintering individuals expressing consistently higher M(sum) and BMR could therefore be seen as better performers with higher chances of winter survival than those exhibiting lower metabolic performance. In this study, we calculated repeatability to evaluate temporal consistency of body mass, BMR and M(sum) within and across three consecutives winters in black-capped chickadees (Poecile atricapillus). We found that body mass was significantly repeatable both within and across winters (R 0.51-0.90). BMR (R 0.29-0.47) was only repeatable within winter while M(sum) was repeatable both among (R 0.33-0.49) and within winters (R 0.33-0.49) with the magnitude and significance of repeatability in both variables depending on the year and whether they were corrected for body mass or body size. The patterns of repeatability observed among years also differed between the two variables. Our findings suggest that the relative ranking of individuals in winter metabolic performance is affected by local ecological conditions and can change within relatively short periods of time.
Assuntos
Aclimatação , Metabolismo Energético , Passeriformes/metabolismo , Estações do Ano , Animais , Metabolismo Basal , Peso CorporalRESUMO
An expert panel analyzed the available evidence and reached a consensus to release 24 recommendations for primary and secondary prevention of gastric cancer (CG) in symptomatic patients, with indication for upper GI endoscopy. The main recommendations include (1) Search for and eradicate H. pylori infection in all cases. (2) Systematic gastric biopsies (Sydney protocol) in all patients over 40 years of age or first grade relatives of patient with CG, to detect gastric atrophy, intestinal metaplasia or dysplasia. (3) Incorporate the OLGA system (Operative Link on Gastritis Assessment) to the pathological report, to categorize the individual risk of CG. (4) Schedule endoscopic follow-up according to the estimated risk of CG, namely annual for OLGA III- IV, every 3 years for OLGA I- II or persistent H. pylori infection, every 5 years for CG relatives without other risk factors and no follow-up for OLGA 0, H. pylori (-). (4) Establish basic human and material resources for endoscopic follow-up programs, including some essential administrative processes, and (5) Suggest the early CG/total CG diagnosis ratio of each institution and the proportion of systematic recording of endoscopic images, as quality indicators. These measures are applicable using currently available resources, they can complement any future screening programs for asymptomatic population and may contribute to improve the prognosis of CG in high-risk populations.
Assuntos
Detecção Precoce de Câncer/métodos , Endoscopia Gastrointestinal , Lesões Pré-Cancerosas/diagnóstico , Neoplasias Gástricas/diagnóstico , Chile , Humanos , Fatores de Risco , Sociedades MédicasRESUMO
AIM: To optimize diagnosis and treatment guidelines for this geographic region, a panel of gastroenterologists, epidemiologists, and basic scientists carried out a structured evaluation of available literature. METHODS: Relevant questions were distributed among the experts, who generated draft statements for consideration by the entire panel. A modified three-round Delphi technique method was used to reach consensus. Critical input was also obtained from representatives of the concerned medical community. The quality of the evidence and level of recommendation supporting each statement was graded according to United States Preventive Services Task Force criteria. RESULTS: A group of ten experts was established. The survey included 15 open-ended questions that were distributed among the experts, who assessed the articles associated with each question. The levels of agreement achieved by the panel were 50% in the first round, 73.3% in the second round and 100% in the third round. Main consensus recommendations included: (1) when available, urea breath and stool antigen test (HpSA) should be used for non-invasive diagnosis; (2) detect and eradicate Helicobacter pylori (H. pylori) in all gastroscopy patients to decrease risk of peptic ulcer disease, prevent o retard progression in patients with preneoplastic lesions, and to prevent recurrence in patients treated for gastric cancer; (3) further investigate implementation issues and health outcomes of H. pylori eradication for primary prevention of gastric cancer in high-risk populations; (4) prescribe standard 14-d triple therapy or sequential therapy for first-line treatment; (5) routinely assess eradication success post-treatment in clinical settings; and (6) select second- and third-line therapies according to antibiotic susceptibility testing. CONCLUSION: These achievable steps toward better region-specific management can be expected to improve clinical health outcomes.
Assuntos
Antibacterianos/uso terapêutico , Técnica Delphi , Infecções por Helicobacter/tratamento farmacológico , Helicobacter pylori/efeitos dos fármacos , Inibidores da Bomba de Prótons/uso terapêutico , Técnicas Bacteriológicas , Consenso , Progressão da Doença , Farmacorresistência Bacteriana , Quimioterapia Combinada , Infecções por Helicobacter/diagnóstico , Infecções por Helicobacter/epidemiologia , Infecções por Helicobacter/microbiologia , Helicobacter pylori/isolamento & purificação , Humanos , América Latina/epidemiologia , Úlcera Péptica/epidemiologia , Úlcera Péptica/microbiologia , Úlcera Péptica/prevenção & controle , Guias de Prática Clínica como Assunto , Lesões Pré-Cancerosas/tratamento farmacológico , Lesões Pré-Cancerosas/epidemiologia , Lesões Pré-Cancerosas/microbiologia , Valor Preditivo dos Testes , Recidiva , Neoplasias Gástricas/epidemiologia , Neoplasias Gástricas/microbiologia , Neoplasias Gástricas/prevenção & controle , Fatores de Tempo , Resultado do TratamentoRESUMO
During periods of cold, small endotherms depend on a continuous supply of food and energy to maintain euthermic body temperature (T(b)), which can be challenging if food is limited. In these conditions, energy-saving strategies are critical to reduce the energetic requirements for survival. Mammals from temperate regions show a wide arrange of such strategies, including torpor and huddling. Here we provide a quantitative description of thermoregulatory capacities and energy-saving strategies in Dromiciops gliroides, a Microbiotherid marsupial inhabiting temperate rain forests. Unlike many mammals from temperate regions, preliminary studies have suggested that this species has low capacity for control and regulation of body temperature, but there is still an incomplete picture of its bioenergetics. In order to more fully understand the physiological capacities of this "living fossil", we measured its scope of aerobic power and the interaction between huddling and torpor. Specifically, we evaluated: (1) the relation between basal (BMR) and maximum metabolic rate (MMR), and (2) the role of huddling on the characteristics of torpor at different temperatures. We found that BMR and MMR were above the expected values for marsupials and the factorial aerobic scope (from [Formula: see text]CO(2)) was 6.0±0.45 (using [Formula: see text]CO(2)) and 6.2±0.23 (using [Formula: see text]O(2)), an unusually low value for mammals. Also, repeatability of physiological variables was non-significant, as in previous studies, suggesting poor time-consistency of energy metabolism. Comparisons of energy expenditure and body temperature (using attached data-loggers) between grouped and isolated individuals showed that at 20°C both average resting metabolic rate and body temperature were higher in groups, essentially because animals remained non-torpid. At 10°C, however, all individuals became torpid and no differences were observed between grouped and isolated individuals. In summary, our study suggests that the main response of Dromiciops gliroides to low ambient temperature is reduced body temperature and torpor, irrespective of huddling. Low aerobic power and low time-consistency of most thermoregulatory traits of Dromiciops gliroides support the idea of poor thermoregulatory abilities in this species.
RESUMO
The microbiotherid marsupial Dromiciops gliroides inhabits the temperate forests of the Southern hemisphere, facing seasonal nutritional and energetic bottlenecks due to its apparently facultative insectivory/frugivory. In order to understand the physiological processes behind this ecological pattern, we studied the morpho-physiological changes that D. gliroides exhibits after dietary acclimation, in a sample of 21 wild-caught individuals fed over 1 month with ad libitum diet of: (1) fruit, (2) insects or (3) a mix of insects and fruit. In addition, we measured oxygen consumption (VO(2)) at resting conditions. We also performed enzyme assays (sucrase, maltase, trehalase and aminopeptidase N) and measurements of organ morphology. We found that D. gliroides cannot fulfil its nutrient requirements only from insects or fruit. It needs a mixed diet in order to maintain its body mass and energy balance. However, as a response of diet acclimation, individuals showed several-fold changes in the activities of aminopeptidase-N, maltase and sucrase (but not trehalase). This result, both the magnitude of change and the simultaneous effects on three enzymes suggests that D. gliroides could exhibit adaptive phenotypic plasticity in the activity of intestinal enzymes. This study suggests also that D. gliroides, the only living representative of the Microbiotheria order, exhibits physiological adaptations to a generalist diet.
Assuntos
Metabolismo Energético , Intestino Delgado/enzimologia , Marsupiais/fisiologia , Adaptação Fisiológica , Animais , Chile , Dieta , Intestino Delgado/anatomia & histologia , Fígado/anatomia & histologia , Marsupiais/metabolismo , Tamanho do Órgão , Consumo de Oxigênio , Fenótipo , Redução de PesoRESUMO
One of the most ubiquitous consequences of feeding in animals is specific dynamic action (SDA), a drastic increment in metabolic rate after a meal, which lasts from a few hours to several days. According to a recent exhaustive review by Secor (2009), studies in SDA are abundant, encompassing all kinds of vertebrates and invertebrates. However, important exceptions are arachnids, as few studies have characterized SDA in this group. Here, we measured the standard metabolic rate (SMR) of the Chilean tarantulas Euathlus truculentus (body mass=7.32±0.7 g; N=32; T(A)=25°C), its inter-individual variation (i.e., repeatability) and its SDA. We measured SMR three or four times in each individual, and we also conducted predation experiments where a prey was consumed by each spider, during a respirometry trial. The SMR of E. truculentus was 0.00049±0.000079 mlCO(2) g(-1) min(-1) which corresponds to 1524 µW (assuming a protein-based diet), 108.4% of the predicted value for arachnids. According to the standard nomenclature for SDA studies, the scope of the SDA for a meal size of 1.26±0.04 g (18% of the spider size) was 6.55±1.1 times the baseline, the time to peak was 45 min, and the magnitude of the SDA was 0.28±0.03 kj, which is 85% of the expected value for invertebrates. Our SMR data are in concordance with previous findings suggesting remarkably low energy metabolism in arachnids, compared with other arthropods. On the other hand, the exceedingly high scope of the postprandial response contrasts with the comparatively low SDA. This fact suggests that spiders spend most of the energy for digestion in a short period after prey capture, which could be a consequence of their external digestion.
Assuntos
Metabolismo Basal/fisiologia , Temperatura Corporal , Metabolismo Energético/fisiologia , Comportamento Alimentar , Período Pós-Prandial/fisiologia , Aranhas/fisiologia , Animais , Peso Corporal , Digestão , Alimentos , Consumo de OxigênioRESUMO
Torpor is the physiologically controlled reduction of metabolic rate and body temperature experienced by small birds and mammals when facing periods of low temperature and/or food shortage. In this study, we provide a first quantitative description of torpor in the relict marsupial Dromiciops gliroides by: (1) characterizing body temperature (T (B)) and torpor patterns, (2) evaluating the combined effects of ambient temperature and different levels of food restriction on torpor incidence and (3) exploring the metabolic depression during torpor. D. gliroides exhibited short bouts of torpor on a daily basis, during which T (B) decreased close to ambient temperature. During the active phase, T (B) also exhibited pronounced variation (range 34-38 degrees C). In order to evaluate the consistency of torpor, we computed the repeatability of T (B). Using the whole dataset, repeatability was significant (tau = 0.28). However, when torpid individuals were excluded from the analysis, repeatability was non-significant: some individuals were more prone to experience torpor than others. Our results indicate that this species also exhibits short bouts of daily torpor, whose depth and duration depends on the joint effects of T (A) and food availability. At T (A) = 20 degrees C, the maximum torpor incidence was found at 70-80% food reduction, while at both extremes of the food continuum (100 and 0-10% food reduction) individuals were completely active, although considerable variation in T (B) was recorded. At T (A) = 10 degrees C, individuals developed a deep form of torpor that was independent of the amount of food provided. On average, torpid D. gliroides reduced their metabolic rate up to 92% of their active values. In general, our results suggest that T (A) was the most immediate determinant of torpor, followed by energy availability.
Assuntos
Ciclos de Atividade , Regulação da Temperatura Corporal/fisiologia , Metabolismo Energético/fisiologia , Abastecimento de Alimentos , Animais , Temperatura Corporal/fisiologia , Marsupiais/fisiologia , TemperaturaRESUMO
In evolutionary physiology, studies of inter-individual variation (i.e. repeatability) in functional capacities are valuable as they indicate - within populations - what attributes could respond to natural selection. Although repeatability and quantitative genetics of physiological traits in energy metabolism of eutherian mammals have been well characterized, few or no studies have been performed on marsupials. We studied the repeatability (i.e. intraclass correlation coefficient, tau) of bioenergetics for Monito del Monte (Dromiciops gliroides), the sole living representative of an otherwise extinct marsupial order (Microbiotheria). We measured resting metabolic rate as CO(2) production (V(CO(2))) and O(2) consumption (V(O(2))) simultaneously, together with minimum thermal conductance (C), evaporative water loss (EWL) and respiratory quotient (RQ), in a sample of ca. 20 individuals. Our results suggest that D. gliroides exhibits poor control of body temperature (T(b)), with a thermal amplitude of ca. 10 degrees C in normothermia. As a consequence, repeatability of T(b) and metabolic rate (either as V(CO(2)) or V(O(2))) were relatively low (tau(T)(b)=0.25+/-0.04, tau(VCO2)=0.14+/-0.03, tau(V)(O2)=0.24+/-0.02, jackknife estimations of standard errors). Thermal conductance exhibited near-zero or negative repeatability and was lower than expected for marsupials. However, we found significant repeatability for RQ and EWL (tau=0.32+/-0.03 and 0.49+/-0.09, respectively). In general, these results suggest that Monito del Monte exhibits some ;reptilian' physiological characteristics. The relatively low repeatability of physiological variables, which otherwise exhibit large inter-individual and genetic variance in eutherian mammals, suggests that these capacities do not exhibit evolutionary potential in the ancient order Microbiotheria.
Assuntos
Variação Genética , Marsupiais/genética , Marsupiais/metabolismo , Animais , Temperatura Corporal , Metabolismo Energético , Consumo de Oxigênio , Condutividade TérmicaRESUMO
Prevalence, modes of transmission, clinical characteristics and outcomes of hepatitis C (HCV) infection vary in different geographical areas. We aim to describe clinical and epidemiological features of Chilean patients infected with hepatitis C virus. An analysis of demographic, epidemiological, clinical and laboratory data of patients referred to a liver clinic and blood donors with chronic hepatitis C was carried out. 147 patients were evaluated, 68 (46%) were male. Median age was 56 years, median infection age was 27 years and median duration of infection was 27 years. 52.5% of the patients were cirrhotic, and estimated risk of progression to cirrhosis was 16% at 20 years from infection. Risk factors for acquisition of the disease among patients were: Blood transfusion 54%, injection drug use 5%, and risky sexual behavior 2%. No factor was identified in 43% of the patients. Twelve of 64 (18.8%) family members tested positive for HCV antibodies. Genotype 1b was predominant (82%), and 52% of patients had high viral load (>850.000 IU/mL). Liver biopsy was available in 50 patients, showing advanced fibrosis in 54%. These patients were in average 10 years older and tended to have longer duration of infection. Hepatocellular carcinoma was present at the moment of enrollment in 7 patients and developed in 4 more patients during follow up (2.4 years). In conclusion, the natural history and clinical characteristics of HCV infection in Chilean patients is similar to that described elsewhere. The main risk factor was blood transfusion. A significant proportion of patients had advanced liver disease or hepatocellular carcinoma at time of diagnosis.