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1.
BMC Anesthesiol ; 24(1): 317, 2024 Sep 06.
Artigo em Inglês | MEDLINE | ID: mdl-39242515

RESUMO

BACKGROUND: Perioperative reflux aspiration presents a grave concern during sedation or general anesthesia, particularly when solid gastric contents prompt acute upper respiratory obstruction, potentially resulting in fatal consequences for patients. Currently, there are limited means for promptly assessing solid gastric contents in clinical settings. Therefore, this study examined the efficacy of ultrasound assessment for solid gastric contents, offering a rapid and non-invasive approach for early detection and decision-making regarding interventions. METHODS: The study included 400 patients scheduled for upper endoscopy procedures, which encompassed both gastroscope and gastroscope combined colonoscopy examinations with sedation. Ultrasound scanning of the antrum was performed while patients were positioned semi-sitting or in the right lateral decubitus (RLD) posture. The evaluation of solid gastric contents relied on direct visual observation during endoscopy. Gastric volume measurement occurred subsequent to endoscopic suction of gastric contents. Receiver operating characteristic curves were utilized to assess the effectiveness of ultrasonography in discerning solid contents. RESULT: Seven patients undergoing gastroscope with sedation were found to have solid gastric contents. The sensitivity, specificity, positive predictive value, and negative predictive value of the ultrasound qualitative evaluation of solid contents were 85.7%, 99%, 60%, and 99.7%, respectively. CONCLUSION: Solid stomach contents can be evaluated qualitatively with reasonable accuracy using ultrasonography. Additionally, in patients undergoing upper endoscopy and assessed to have solid gastric contents with ultrasound, administration of mild sedation is recommended. TRIAL REGISTRATION: www.chictr.org.cn (ChiCTR2100048994); registered 19/07/2021.


Assuntos
Conteúdo Gastrointestinal , Ultrassonografia , Humanos , Masculino , Feminino , Pessoa de Meia-Idade , Conteúdo Gastrointestinal/diagnóstico por imagem , Idoso , Ultrassonografia/métodos , Adulto , Sedação Consciente/métodos , Colonoscopia/métodos , Sensibilidade e Especificidade , Gastroscópios , Estudos Prospectivos
2.
Environ Pollut ; 360: 124659, 2024 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-39097262

RESUMO

The ingestion of debris by marine fauna is a growing threat to biodiversity. This study aimed to evaluate and characterize litter ingestion by odontocetes from the Western South Atlantic. Between 2018 and 2022, 154 stomachs from six species were collected from stranded individuals and incidental captures. Stomach contents were analyzed with the naked eye and items of anthropic origin found were counted and physically/chemically characterized. Generalized Linear Models were used to evaluate the influence of biological factors on the presence/absence of litter in stomachs, and for Pontoporia blainvillei only, the influence of these factors on the number of ingested items was also tested; additionally, a temporal analysis of ingestion was done for this species (1994-2022). A total of 156 items, mainly macro-sized plastics made of polypropylene, were found in 52 stomachs of four species: Tursiops spp. (FO% = 3.3%), Steno bredanensis (10.0%), Delphinus delphis (28.6%) and P. blainvillei (47.5%). The presence/absence of litter was explained only by species (χ2 = 28.29 and p < 0.001). For P. blainvillei, a threatened species in the region, the number of items was positively influenced by individual size (χ2 = 6.01 and p = 0.01) and sex (χ2 = 7.93 and p = 0.005). There was an increase in plastic ingestion by this species over the years (χ2 = 121.6 and p < 0.001) and it was estimated that 75% of P. blainvillei stomachs will contain plastic by 2040. The ingestion of litter by odontocetes from the Western South Atlantic was confirmed and the potential risks posed by this type of pollution were evidenced, especially since these species also face other anthropic pressures. These results further demonstrate the increasing threat of litter in the ocean and highlight the importance of circularity of plastics and proper waste management.


Assuntos
Espécies em Perigo de Extinção , Plásticos , Plásticos/análise , Animais , Monitoramento Ambiental/métodos , Oceano Atlântico , Feminino , Conteúdo Gastrointestinal/química , Masculino , Ingestão de Alimentos , Resíduos/análise
3.
Sci Rep ; 14(1): 19300, 2024 08 28.
Artigo em Inglês | MEDLINE | ID: mdl-39198502

RESUMO

Cichlid fishes in the African Great Lakes have undergone explosive speciation, acquiring markedly varying ecologies and diets. There are multiple lineages of scale-eating cichlids, and their natural history and evolutionary ecology is only partially understood. We examined the feeding habit of Docimodus evelynae, a known scale eater, in Lake Malawi. The stomach contents of young individuals mainly consisted of unknown 1 mm hard, white warts (> 30%). To clarify the origin of these warts, we conducted an X-ray fluorometer analysis, and found they were rich in sulphur but low in silicon and calcium, suggesting they were epidermal tissues. Histological and morphological analyses revealed they were multicellular and cup-shaped. These characteristics matched only those of the pearl organs of the coexisting cyprinid Labeo cylindricus. DNA was extracted from the warts found in the stomach of five D. evelynae individuals, followed by PCR using primers targeting the partial COI gene of L. cylindricus. The resulting sequences exhibited 98% similarity to those of L. cylindricus. Pearl organs, never reported as a primary food for fish, could offer a substantial nutritional source based on calorific calculations. Understanding how this peculiar diet is foraged is essential for full comprehension of the food-web structure in this lake.


Assuntos
Ciclídeos , Lagos , Animais , Malaui , Comportamento Predatório , Filogenia , Comportamento Alimentar , Conteúdo Gastrointestinal
4.
J Forensic Leg Med ; 106: 102732, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-39089135

RESUMO

Glufosinate is a widely and increasingly used non-selective, broad-spectrum herbicide. Although cases of glufosinate poisoning are frequently reported, they are rarely documented in forensic case reports, particularly in fatal instances. The present study examined six cases of glufosinate poisoning, including a fatal case involving a 25-year-old female found deceased by the roadside, with an empty 1000 mL bottle labeled "glufosinate" by her side. Biological specimens such as plasma or cardiac blood, gastric contents, and liver tissues were collected for quantitative analysis of glufosinate levels using LC-MS/MS. In five cases of acute glufosinate poisoning, glufosinate plasma concentrations ranged from 0.62 to 3.92 µg/mL. In the fatal case, the concentrations of glufosinate in cardiac blood, gastric contents, and liver tissues were 8.41 µg/mL, 31.25 µg/mL, and 66.1 µg/g, respectively. The pathological autopsy concluded that the cause of death was acute cardio-respiratory failure due to glufosinate poisoning, characterized by multi-organ congestion without specific pathological findings. The toxicological data provided in this study aim to serve as a critical reference for future clinical treatment and forensic validation of glufosinate poisoning-related deaths.


Assuntos
Aminobutiratos , Toxicologia Forense , Conteúdo Gastrointestinal , Herbicidas , Fígado , Humanos , Feminino , Adulto , Fígado/química , Fígado/patologia , Conteúdo Gastrointestinal/química , Aminobutiratos/intoxicação , Aminobutiratos/análise , Aminobutiratos/sangue , Herbicidas/intoxicação , Herbicidas/análise , Cromatografia Líquida , Masculino , Pessoa de Meia-Idade , Adulto Jovem , Espectrometria de Massas em Tandem
5.
J Texture Stud ; 55(4): e12851, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38952153

RESUMO

Rheological properties of gastric contents depend on the food ingested, and on the volume and composition of secretions from the host, which may vary. This study investigates the impact of saliva regular incorporation in the stomach after a meal on the rheological properties of gastric contents, considering two levels of salivary flow (low = 0.5 and high = 1.5 mL/min). In vitro chymes were obtained by mixing sour cream, simulated gastric fluid, two different volumes of oral fluid (at-rest human saliva, SSF for Simulated Salivary Fluid or water) and adjusting pH at 3. Chymes samples were characterized at 37°C for their particle size and rheological properties. Overall, particle size distribution was not different between samples: incorporating a larger volume of saliva resulted in more heterogeneity, but the surface area moment D[3,2] and volume moment D[4,3] did not differ significantly with the oral fluid type. Shear viscosity of chyme samples was higher when saliva was incorporated, in comparison with water or SSF. In addition, as shown from data extracted at γ ̇ $$ \dot{\gamma} $$ = 20 s-1 the higher the fluid volume the lower the shear viscosity, which is attributed to a dilution effect. However, this dilution effect was attenuated in the case of saliva, most likely due to its composition in organic compounds (e.g., mucins) contributing to the rheological properties of this biological fluid. In these in vitro conditions, both saliva and the salivation rate had a significant but slight impact on the rheological properties of gastric contents (of the order of 1-5 mPa s at γ ̇ $$ \dot{\gamma} $$ = 20 s-1).


Assuntos
Tamanho da Partícula , Reologia , Saliva , Saliva/química , Humanos , Viscosidade , Conteúdo Gastrointestinal/química , Concentração de Íons de Hidrogênio , Suco Gástrico/química
6.
J Anim Sci ; 1022024 Jan 03.
Artigo em Inglês | MEDLINE | ID: mdl-38995038

RESUMO

Fermentation of dietary and endogenous protein in the hindgut is generally considered detrimental to the health of pigs. We investigated the in vitro fermentation potential of porcine endogenous protein in ileal digesta and colonic mucus, using a N-free buffer with an excess of fermentable carbohydrates. Urea, whey protein isolate (WPI, positive control), WPI hydrolysate (WPIH), and combinations of the latter two were used to validate the assay. A new biphasic model, including a linear end simulation, fitted to the gas production data over a 48-h period identified the time point when substrate fermentation ended. A higher degree of hydrolysis of WPI resulted in a higher maximum gas production rate (Rmax, P < 0.01). Differences in Rmax and the time required to reach Rmax were observed among ileal digesta samples, with Rmax increasing with the insoluble protein content, and the highest Rmax occurring with colonic mucus samples (P < 0.05). The endogenous proteins entering the large intestine of pigs can ferment more rapidly compared to highly soluble and digestible protein sources, with Rmax positively correlated with decreasing solubility of endogenous nitrogenous components.


Protein fermentation in the hindgut of pigs can impact their health, affecting factors like growth rates and feed efficiency. Besides dietary protein, up to 50% of the protein entering the large intestine of growing pigs may be of endogenous origin. Therefore, we explored the fermentation potential of endogenous proteins compared to a well-known protein source, whey protein isolate (WPI). In developing and validating an in vitro gas production technique, we employed urea, WPI, WPI hydrolysate, and various combinations as substrates. The study introduces a new biphasic model for in vitro gas production, offering a detailed analysis of the fermentation process over a 48-h period. Our results revealed that porcine endogenous proteins can undergo rapid fermentation because the maximum gas production rate was higher compared to WPI. This insight is crucial for understanding the dynamics of protein fermentation in pigs. Additionally, we explored the solubility and molecular size of proteins, providing a comprehensive understanding of their fermentation characteristics. We found that endogenous proteins were less soluble compared to WPI but contained more smaller peptides. Unraveling the complexities of protein fermentation in pigs contributes to improvement of feed formulation for optimal gut health.


Assuntos
Proteínas Alimentares , Fermentação , Animais , Suínos , Proteínas Alimentares/metabolismo , Digestão/fisiologia , Íleo/metabolismo , Colo/metabolismo , Colo/microbiologia , Proteínas do Soro do Leite/metabolismo , Conteúdo Gastrointestinal/química
7.
BMJ Open ; 14(7): e081830, 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39013655

RESUMO

OBJECTIVE: The utilisation of pH level measurements from gastric contents may indicate the preferred tip position of a nasogastric tube or monitor the efficacy of stress ulcer prophylaxis in critically ill patients. We aimed to determine the accuracy of pH strip (pHS) tests and pH liquid (pHL) tests compared with the standard pH meter (pHM). DESIGN: Diagnostic accuracy study. SETTING: Gastric contents from medically critically ill patients. PARTICIPANTS: In total, 113 gastric samples were collected from 27 critically ill patients. OUTCOME MEASURE: The level of pH measured by pHM, pHS and pHL. RESULTS: The pH values measured by pHM, pHS and pHL were 5.83 (IQR 5.12-6.61), 5.50 (IQR 5.00-6.00) and 5.75 (IQR 5.25-6.25), respectively. The pHS test showed greater accuracy, exhibiting a more positive correlation with the standard pHM measurement than the pHL test, with Y=0.95*X+0.56; rho=0.91, p<0.001, and Y=1.09*X - 0.72; rho=0.75, p<0.001, respectively. However, the pHS test demonstrated less agreement with the pHM than the pHL test, with biases of -0.27 versus 0.18, respectively. Noticeably, a slight variation in pHL from the standard pH values was found when we measured gastric contents with a pH lower than 5. CONCLUSION: Both the pHS and pHL methods were good options for measuring gastric pH in critically ill patients. However, it was advisable to find alternative approaches to the pHL testing method when anticipated gastric acidity levels fall below 5. TRIAL REGISTRATION NUMBER: TCTR20220530004.


Assuntos
Estado Terminal , Determinação da Acidez Gástrica , Conteúdo Gastrointestinal , Humanos , Feminino , Masculino , Concentração de Íons de Hidrogênio , Pessoa de Meia-Idade , Conteúdo Gastrointestinal/química , Idoso , Fitas Reagentes , Adulto , Reprodutibilidade dos Testes
8.
BMC Anesthesiol ; 24(1): 237, 2024 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-39009966

RESUMO

BACKGROUND: Failure to adhere to perioperative fasting requirements increases aspiration risk and can lead to delay or cancellation of surgery. Point of care gastric ultrasound may guide decision-making to delay, cancel or proceed with surgery. METHODS: This study aimed to describe gastric contents using point of care gastric ultrasound in pediatric patients with known fasting guideline violations presenting for elective surgery. This was a single-center retrospectivechart review of gastric ultrasound scans in patients presenting for elective surgeries with "nothing by mouth" violation (per fasting guidelines) or unclear fasting status. The primary outcome is description of gastric contents using point of care ultrasound. The ultrasound findings were classified as low-risk for aspiration (empty, clear fluid < 1.5 ml/kg), high-risk (solids, clear fluid > 1.5 ml/kg), or inconclusive study. Gastric ultrasound findings were communicated to the attending anesthesiologist. For patients proceeding without delay the estimated time saved was defined as the difference between ultrasound scan time and presumed case start time based on American Society of Anesthesiologists fasting guidelines. RESULTS: We identified 106 patients with a median age of 4.8 years. There were 31 patients (29.2%) that had ultrasound finding of high-risk gastric contents. These patients had cases that were delayed, cancelled or proceeded with rapid sequence intubation. Sixty-six patients (62.3%) were determined to be low-risk gastric contents and proceeded with surgery without delay. For these patients, a median of 2.6 h was saved. No aspiration events were recorded for any patients. CONCLUSIONS: It is feasible to use preoperative point of care gastric ultrasound to determine stomach contents and risk-stratify pediatric patients presenting for elective surgical procedures with fasting non-adherence. Preoperative gastric ultrasound may have a role in determining changes in anesthetic management in this patient population.


Assuntos
Procedimentos Cirúrgicos Eletivos , Jejum , Conteúdo Gastrointestinal , Sistemas Automatizados de Assistência Junto ao Leito , Cuidados Pré-Operatórios , Estômago , Ultrassonografia , Humanos , Estudos Retrospectivos , Procedimentos Cirúrgicos Eletivos/métodos , Feminino , Masculino , Pré-Escolar , Ultrassonografia/métodos , Criança , Cuidados Pré-Operatórios/métodos , Conteúdo Gastrointestinal/diagnóstico por imagem , Estômago/diagnóstico por imagem , Anestesia/métodos , Lactente , Adolescente
9.
A A Pract ; 18(7): e01824, 2024 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-39023194

RESUMO

Gastric ultrasound estimates stomach contents in perioperative patients. A 10-year-old boy with abdominal rhabdomyosarcoma, who received abdominal radiation, developed gastroparesis and was scheduled for endoscopic gastrointestinal pyloric dilation. Point-of-care gastric ultrasound revealed gastric antral cross-sectional area of 6.5 cm2 (estimated gastric content ~30 mL). However, dynamic right-to-left ultrasound revealed more hypoechoic material in the fundus of the stomach. On induction ~125 mL of stomach contents was suctioned. Antral measurements may not accurately predict the stomach contents in the setting of a stiff/fixed antrum. Scanning from antrum to fundus determined contents more accurately, especially with a prior history of abdominal radiation.


Assuntos
Sistemas Automatizados de Assistência Junto ao Leito , Antro Pilórico , Ultrassonografia , Humanos , Masculino , Criança , Antro Pilórico/diagnóstico por imagem , Rabdomiossarcoma/diagnóstico por imagem , Gastroparesia/diagnóstico por imagem , Estômago/diagnóstico por imagem , Conteúdo Gastrointestinal/diagnóstico por imagem , Neoplasias Abdominais/diagnóstico por imagem
10.
J Fish Biol ; 105(2): 459-471, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38964749

RESUMO

Estuaries are essential habitats for recreational and commercial fish that are shaped by both natural and anthropogenic processes. In Louisiana a combination of climate change and planned coastal restoration actions is predicted to increase freshwater introduction to coastal estuaries. As such there is a need to quantify the relationships between estuarine fish ecology and salinity to aid in predicting how species will respond to shifts in salinity. We investigated the relative abundance and dietary niches of adult (24.5 ± 5.4 cm standard length) spotted seatrout Cynoscion nebulosus across varying salinity regimes (oligohaline, mesohaline, and polyhaline) within Barataria Bay, Louisiana, using a combination of net sampling and gut content and stable isotopes analysis. We found that the relative abundance of C. nebulosus was lowest at the oligohaline site, translating to approximately five fewer fish captured for every single psu decrease in a site's average annual salinity. In contrast, we found that diets and, to a lesser extent, isotopic niches had a high degree of overlap across sites with differing salinity regimes. Fish and penaeid shrimp were the most common and important prey taxa recovered from guts at all sites. The small isotopic differences found among sites were likely due to spatial variation in hydrogeochemical baselines, and the observed isotopic overlap provides support for the idea that C. nebulosus move between adjacent salinity regimes and forage throughout Barataria Bay. Our results contribute to a greater understanding of the salinity preference and trophic ecology of C. nebulosus that can aid in predicting their responses to future salinity and habitat changes within Barataria Bay associated with predicted climate change and planned coastal restoration actions.


Assuntos
Dieta , Estuários , Salinidade , Animais , Louisiana , Perciformes/fisiologia , Cadeia Alimentar , Conteúdo Gastrointestinal/química , Isótopos de Carbono/análise , Isótopos de Nitrogênio/análise
11.
Clin Toxicol (Phila) ; 62(9): 596-597, 2024 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-39078015

RESUMO

INTRODUCTION: Ingestion of gasoline can cause severe pulmonary and gastrointestinal complications. Computed tomography may reveal characteristic findings. CASE SUMMARY: A 61-year-old man had gastrointestinal symptoms, and subsequently developed respiratory distress and altered mental status after ingesting approximately 150 mL of gasoline. IMAGES: Abdominal computed tomography revealed a characteristic three-layered appearance of intestinal contents, likely representing intestinal fluid, ingested gasoline, and gas. Chest computed tomography showed bilateral pulmonary infiltrates consistent with pneumonitis. CONCLUSION: Recognition of the characteristic three-layered appearance of the intestinal contents on abdominal computed tomography might aid in the diagnosis of gasoline ingestion.


Assuntos
Gasolina , Tomografia Computadorizada por Raios X , Humanos , Masculino , Pessoa de Meia-Idade , Gasolina/intoxicação , Conteúdo Gastrointestinal/química
12.
J Equine Vet Sci ; 141: 105152, 2024 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-39074692

RESUMO

Concentrations of starch, mono- and disaccharides, fructans, hemicellulose and cellulose were analysed in feed and gastric digesta of horses in relation to acid insoluble ash as a marker indigestible in the stomach. Twenty-four horses were allocated to pasture 24 h/d (PST; n = 4), hay ad libitum (HAY; n = 8), hay ad lib. and oats at 1 g starch/kg body weight (BWT)/meal (OS1; n = 6) and hay ad lib. and oats at 2 g starch/kg BWT/meal (OS2; n = 5). One horse was excluded from the analysis. The horses were fed the ration a minimum of 34 days. Following euthanasia and dissection, digesta was sampled from Pars nonglandularis (PNG) and Pars glandularis (PG). Oat starch concentration in gastric digesta decreased from 309 to 174 g/kg dry matter (DM) in OS1 (44 %-reduction) and from 367 to 261 g/kg DM in OS2 (29 %-reduction) (P < 0.001). Glucose, fructose and sucrose disappeared from gastric digesta distinctly more in PST, HAY and OS1 than in OS2. In PST and HAY, sucrose concentration was completely cleared (P < 0.001). The concentration of fructans was reduced predominantly in PST (84 %-reduction) and HAY (54 %-reduction), mainly in the PNG (P < 0.05). Fructan degradation did not occur in the high-starch diet (OS2). Some evidence for fibre degradation was observed in PST (P < 0.01). Soluble carbohydrates disappear from the stomach dependent on the type of ration, which may lead to changes in the composition of the gastric microbial community and the endogenous response.


Assuntos
Ração Animal , Avena , Digestão , Animais , Cavalos , Ração Animal/análise , Avena/química , Digestão/fisiologia , Dieta/veterinária , Fenômenos Fisiológicos da Nutrição Animal , Metabolismo dos Carboidratos , Masculino , Estômago , Feminino , Conteúdo Gastrointestinal/química
13.
Ying Yong Sheng Tai Xue Bao ; 35(4): 961-969, 2024 Apr 18.
Artigo em Chinês | MEDLINE | ID: mdl-38884231

RESUMO

Research about feeding ecology of fish is important to understand individual behavior and population development, which is also the basic to analyze trophic structure and function of aquatic ecosystems. Chaetrichthys stigmatias is one of the key species in the Haizhou Bay fisheries ecosystem, which has critical ecological niche within the food web. In this study, we collected samples through bottom trawl surveys during the fall of 2018 in the Haizhou Bay, and analyzed the feeding ecology of C. stigmatias based on both stomach content analysis and stable isotope technology. The results showed that the primary diet groups for C. stigmatias were Ophiuroidea and Shrimp, including Ophiothrix marenzelleri, Ophiopholis mirabilis, Ophiura sarsii, Penaeidae, and Alpheus japonicus. The range of δ13C values of C. stigmatias was from -19.39‰ to -15.74‰, with an average value of (-18.07±0.87)‰, which had no significant correlation with body length. The range of δ15N values was from 8.16‰ to 12.86‰, with an average value of (10.14±1.51)‰, which was positively correlated with body length. The trophic level of C. stigmatias showed a positive relationship with body length, with an average value of (3.74±0.34) and a range value of 3.32 to 4.20 among different size groups. The contribution rates of different prey groups varied significantly. Based on the structural equation modeling, we found that the feeding intensity of C. stigmatias was primally influenced by body length, sea bottom salinity, sea bottom temperature, and water depth, with a particularly signi-ficant positive correlation with body length. The combination of stable isotope technology and stomach content analysis methods could contribute to comprehensive understanding on the feeding ecology of C. stigmatias, providing essential data and foundation for research on trophic structures and resource conservation in the Haizhou Bay ecosystem.


Assuntos
Baías , Ecossistema , Comportamento Alimentar , Estações do Ano , Animais , China , Cadeia Alimentar , Peixes , Oceanos e Mares , Conteúdo Gastrointestinal/química
16.
An Acad Bras Cienc ; 96(2): e20230652, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38922275

RESUMO

Trophic plasticity is a distinctive feature of freshwater fishes, representing an essential strategy for fish living in resource-variable environments. We analyzed the stomach contents of individuals sampled in two Atlantic Forest streams to identify the primary food sources consumed by Psalidodon aff. fasciatus and verify the existence of spatial, seasonal, and ontogenetic variations. The diet was determined by analyzing the stomach contents using the Volume Method to quantify the importance of food items. In general, Psalidodon aff. fasciatus was classified as an omnivorous species, consuming mainly insects, plant material, and filamentous algae. The results also showed significant effects for all factors considered (spatial, seasonal, and ontogenetic). Finally, Psalidodon aff. fasciatus demonstrated considerable trophic plasticity, which can result in better use of available resources in the environment and improved resource partitioning, reducing intraspecific and interspecific competition.


Assuntos
Characidae , Conteúdo Gastrointestinal , Rios , Estações do Ano , Animais , Brasil , Characidae/fisiologia , Characidae/classificação , Comportamento Alimentar/fisiologia , Florestas , Cadeia Alimentar
17.
Sci Rep ; 14(1): 14102, 2024 06 19.
Artigo em Inglês | MEDLINE | ID: mdl-38890338

RESUMO

Large predators have disproportionate effects on their underlying food webs. Thus, appropriately assigning trophic positions has important conservation implications both for the predators themselves and for their prey. Large-bodied predators are often referred to as apex predators, implying that they are many trophic levels above primary producers. However, theoretical considerations predict both higher and lower trophic position with increasing body size. Nitrogen stable isotope values (δ15N) are increasingly replacing stomach contents or behavioral observations to assess trophic position and it is often assumed that ontogenetic dietary shifts result in higher trophic positions. Intraspecific studies based on δ15N values found a positive relationship between size and inferred trophic position. Here, we use datasets of predatory vertebrate ectotherms (crocodilians, turtles, lizards and fishes) to show that, although there are positive intraspecific relationships between size and δ15N values, relationships between stomach-content-based trophic level (TPdiet) and size are undetectable or negative. As there is usually no single value for 15N trophic discrimination factor (TDF) applicable to a predator species or its prey, estimates of trophic position based on δ15N in ectotherm vertebrates with large size ranges, may be inaccurate and biased. We urge a reconsideration of the sole use of δ15N values to assess trophic position and encourage the combined use of isotopes and stomach contents to assess diet and trophic level.


Assuntos
Tamanho Corporal , Cadeia Alimentar , Isótopos de Nitrogênio , Comportamento Predatório , Vertebrados , Animais , Isótopos de Nitrogênio/análise , Isótopos de Nitrogênio/metabolismo , Comportamento Predatório/fisiologia , Lagartos/fisiologia , Lagartos/metabolismo , Peixes/fisiologia , Conteúdo Gastrointestinal/química , Tartarugas/fisiologia , Tartarugas/metabolismo
18.
Fish Shellfish Immunol ; 151: 109729, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38942252

RESUMO

Monitoring stress levels of farmed Atlantic salmon (Salmo salar) is important to ensure fish welfare and optimize farm operations. Feces could be a promising matrix for assessing stress responses in fish, based on their properties of low-invasive sampling and allowing repeated sampling over time. Meanwhile, elevated levels of cortisol metabolites (CMs) in feces indicate the increases in plasma cortisol levels (PLA) after exposure to acute stress. However, the dynamics of fecal CMs following acute stress in Atlantic salmon remain unclear. In this study, a confinement stress involving chasing and crowding was conducted to investigate the responses of gastrointestinal CMs to an acute stressor in Atlantic salmon. The post-smolts, with an average weight of 155.21 g, were sampled before and at 30 min, 1.5, 6, 12, 18, 24, 36, and 48 h after the onset of stress. Blood and gastrointestinal contents from the stomach, proximal intestine, and distal intestine of each fish were collected and subsequently analyzed, using competitive enzyme-linked immunosorbent assay (ELISA). The results demonstrated that the pre-stress level of PLA was low (4.28 ± 6.13 ng/ml) and reached a peak within 30 min following stress. The levels of CMs in gastrointestinal contents from stomach (SCMs), proximal intestine (PCMs), and distal intestine (DCMs) in pre-stress group were 0.82 ± 0.50, 18.31 ± 6.14 and 16.04 ± 6.69 ng/g, respectively. Gastrointestinal CMs increased significantly within 30 min and the peak levels of SCMs (3.51 ± 3.75 ng/g), PCMs (68.19 ± 23.71 ng/g) and DCMs (65.67 ± 23.37 ng/g) were found at 1.5 h post-stress. The significant increases in PCMs and DCMs post-stress validate the biological relevance of measuring intestinal CMs for assessing acute stress responses in Atlantic salmon. No significant difference was noted between PCMs and DCMs across all samples, suggesting that intestinal contents can serve as a suitable matrix compared with feces when measuring the responses of CMs to acute stress. The time lag between the peak of PLA levels and their reflection in the intestinal contents exceeded 1 h, indicating that using intestinal contents as a matrix to assess stress levels in fish can extend and delay the sampling window. This study highlights valuable guidance for determining the optimal times to utilize intestinal contents for measuring stress responses, providing further insights into the dynamics of fecal CM following acute stress.


Assuntos
Fezes , Hidrocortisona , Salmo salar , Estresse Fisiológico , Animais , Hidrocortisona/sangue , Estresse Fisiológico/fisiologia , Fezes/química , Aglomeração , Trato Gastrointestinal/metabolismo , Conteúdo Gastrointestinal/química
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