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1.
Adv Tech Stand Neurosurg ; 50: 231-275, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38592533

RESUMO

The treatment of pathologies located within and surrounding the orbit poses considerable surgical challenges, due to the intricate presence of critical neurovascular structures in such deep, confined spaces. Historically, transcranial and craniofacial approaches have been widely employed to deal with orbital pathologies. However, recent decades have witnessed the emergence of minimally invasive techniques aimed at reducing morbidity. Among these techniques are the endoscopic endonasal approach and the subsequently developed endoscopic transorbital approach (ETOA), encompassing both endonasal and transpalpebral approaches. These innovative methods not only facilitate the management of intraorbital lesions but also offer access to deep-seated lesions within the anterior, middle, and posterior cranial fossa via specific transorbital and endonasal corridors. Contemporary research indicates that ETOAs have demonstrated exceptional outcomes in terms of morbidity rates, cosmetic results, and complication rates. This study aims to provide a comprehensive description of endoscopic-assisted techniques that enable a 360° access to the orbit and its surrounding regions. The investigation will delve into indications, advantages, and limitations associated with different approaches, while also drawing comparisons between endoscopic approaches and traditional microsurgical transcranial approaches.


Assuntos
Endoscopia , Órbita , Humanos , Órbita/cirurgia , Fossa Craniana Posterior , Espaços Confinados , Postura Sentada
2.
Environ Sci Technol ; 58(12): 5229-5243, 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38466915

RESUMO

Silicone-based passive samplers, commonly paired with gas chromatography-mass spectrometry (GC-MS) analysis, are increasingly utilized for personal exposure assessments. However, its compatibility with the biotic exposome remains underexplored. In this study, we introduce the wearable silicone-based AirPie passive sampler, coupled with nontargeted liquid chromatography with high-resolution tandem mass spectrometry (LC-HRMS/MS), GC-HRMS, and metagenomic shotgun sequencing methods, offering a comprehensive view of personalized airborne biotic and abiotic exposomes. We applied the AirPie samplers to 19 participants in a unique deep underwater confined environment, annotating 4,390 chemical and 2,955 microbial exposures, integrated with corresponding transcriptomic data. We observed significant shifts in environmental exposure and gene expression upon entering this unique environment. We noted increased exposure to pollutants, such as benzenoids, polycyclic aromatic hydrocarbons (PAHs), opportunistic pathogens, and associated antibiotic-resistance genes (ARGs). Transcriptomic analyses revealed the activation of neurodegenerative disease-related pathways, mostly related to chemical exposure, and the repression of immune-related pathways, linked to both biological and chemical exposures. In summary, we provided a comprehensive, longitudinal exposome map of the unique environment and underscored the intricate linkages between external exposures and human health. We believe that the AirPie sampler and associated analytical methods will have broad applications in exposome and precision medicine.


Assuntos
Expossoma , Doenças Neurodegenerativas , Hidrocarbonetos Policíclicos Aromáticos , Dispositivos Eletrônicos Vestíveis , Humanos , Espaços Confinados , Transcriptoma , Monitoramento Ambiental/métodos , Silicones
3.
J Chem Inf Model ; 63(21): 6706-6716, 2023 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-37907068

RESUMO

Modeling of complex liquids at solid surfaces and in confinement is gaining attention due to an increase in computer power and advancement of simulation techniques. Therefore, tools to set up structures and for analysis are needed. In this paper, we present CONAN─a Python code designed to facilitate the study of liquids interacting with solid structures, such as walls or pores. Among other things, the program provides the option to generate a variety of different structures, including carbon walls and nanotubes and their boron nitride analogs, as well as the ability to analyze various structural properties of confined and interfacial liquids. In the case of the ionic liquid 1-butyl-3-methylimidazolium acetate in carbon nanotubes of different sizes, we demonstrate the abilities of our tool. The average density within the confinement highly depends on the carbon nanotube size, and it is generally lower than the density of the bulk liquid. The arrangement of the individual species within the tube also depends on size, with radial layers forming within the tubular confinement. The density is largely increased in the respective layers, while it is drastically reduced between the layers.


Assuntos
Líquidos Iônicos , Nanotubos de Carbono , Nanotubos de Carbono/química , Espaços Confinados , Líquidos Iônicos/química
4.
Mol Biol Cell ; 34(12): ar122, 2023 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-37672340

RESUMO

The invasive potential of glioblastoma cells is attributed to large changes in pressure and volume, driven by diverse elements, including the cytoskeleton and ion cotransporters.  However, how the cell actuates changes in pressure and volume in confinement, and how these changes contribute to invasive motion is unclear. Here, we inhibited SPAK activity, with known impacts on the cytoskeleton and cotransporter activity and explored its role on the migration of glioblastoma cells in confining microchannels to model invasive spread through brain tissue. First, we found that confinement altered cell shape, inducing a transition in morphology that resembled droplet interactions with a capillary vessel, from "wetting" (more adherent) at low confinement, to "nonwetting" (less adherent) at high confinement. This transition was marked by a change from negative to positive pressure by the cells to the confining walls, and an increase in migration speed. Second, we found that the SPAK pathway impacted the migration speed in different ways dependent upon the extent of wetting. For nonwetting cells, SPAK inhibition increased cell-surface tension and cotransporter activity. By contrast, for wetting cells, it also reduced myosin II and YAP phosphorylation. In both cases, membrane-to-cortex attachment is dramatically reduced. Thus, our results suggest that SPAK inhibition differentially coordinates cotransporter and cytoskeleton-induced forces, to impact glioblastoma migration depending on the extent of confinement.


Assuntos
Glioblastoma , Humanos , Glioblastoma/metabolismo , Espaços Confinados , Citoesqueleto/metabolismo , Fosforilação , Microtúbulos/metabolismo
5.
Zhonghua Wei Zhong Bing Ji Jiu Yi Xue ; 35(7): 777-781, 2023 Jul.
Artigo em Chinês | MEDLINE | ID: mdl-37545462

RESUMO

Major natural disasters seriously threaten human life and health. After earthquakes and other catastrophes, survivors are often trapped in the confined spaces caused by the collapse of ground and buildings, with relative separation from the outside world, restricted access, complex environment, and oncoming or ongoing unsafety, leading to the rescue extremely difficult. In order to save lives and improve the outcome more efficiently in the confined spaces after natural disasters, it is very important to standardize and reasonably apply the trauma assessment and first aid workflow. This study focuses on trauma assessment and first aid. From the aspects of trauma assessment, vital signs stabilization, hemostasis and bandaging, post-trauma anti-infection, and the transportation of patients, a trauma first aid work process suitable for a small space of a major natural disaster is formed, It is helpful to realize the immediate and efficient treatment of trauma in the confined spaces after natural catastrophes, to reduce the rate of death and disability and improve the outcome of patients.


Assuntos
Desastres , Terremotos , Humanos , Primeiros Socorros , Espaços Confinados
6.
J Occup Environ Hyg ; 20(8): 322-328, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37159506

RESUMO

In 2022, a confined space entry accident occurred on a Danish product tanker in which two technicians died from hydrogen sulfide poisoning during the inspection of an empty cargo tank that had contained vegetable cooking oil. The source of the hydrogen sulfide was enigmatic. About three weeks before the accident, the cargo tank was prewashed with seawater. The wash water did not seem likely to present a toxic hazard and was left in the tank. However, the seawater's natural content of dissolved sulfate was converted to sulfide by sulfate-reducing bacteria, and the low-sulfur vegetable oil residue provided the nutrients necessary for bacterial growth. Calculations confirm that sulfate in just 10 m3 of plain seawater is sufficient to create an immediately fatal concentration of H2S gas in the 4,500 m3 cargo tank of the product tanker. Accident statistics show that fatal accidents within enclosed spaces are a serious and stubborn problem. Strict adherence to routine forced ventilation and extensive gas testing of cargo tanks before entry would offer simple and effective preventive measures.


Assuntos
Sulfeto de Hidrogênio , Espaços Confinados , Sulfetos , Água do Mar , Sulfatos
7.
Nano Lett ; 23(10): 4439-4447, 2023 05 24.
Artigo em Inglês | MEDLINE | ID: mdl-37166380

RESUMO

The binding of ligands to receptors within a nanoscale small space is relevant in biology, biosensing, and affinity filtration. Binding in confinement can be studied with biological systems but under the limitation that essential parameters cannot be easily controlled including receptor type and position within the confinement and its dimensions. Here we study molecular recognition with a synthetic confined nanopore with controllable pore dimension and molecular DNA receptors at different depth positions within the channel. Binding of a complementary DNA strand is studied at the single-molecule level with atomic force microscopy. Following the analysis, kinetic association rates are lower for receptors positioned deeper inside the pore lumen while dissociation is faster and requires less force. The phenomena are explained by the steric constraints on molecular interactions in confinement. Our study is the first to explore recognition in DNA nanostructures with atomic force microscopy and lays out new tools to further quantify the effect of nanoconfinement on molecular interactions.


Assuntos
Nanoporos , Microscopia de Força Atômica , Espaços Confinados , DNA/química , Nanotecnologia/métodos
8.
Angew Chem Int Ed Engl ; 62(26): e202304303, 2023 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-37130008

RESUMO

One striking feature of enzyme is its controllable ability to trap substrates via synergistic or cooperative binding in the enzymatic pocket, which renders the shape-selectivity of product by the confined spatial environment. The success of shape-selective catalysis relies on the ability of enzyme to tune the thermodynamics and kinetics for chemical reactions. In emulation of enzyme's ability, we showcase herein a targeting strategy with the substrate being anchored on the internal pore wall of metal-organic frameworks (MOFs), taking full advantage of the sterically kinetic control to achieve shape-selectivity for the reactions. For this purpose, a series of binding site-accessible metal metalloporphyrin-frameworks (MMPFs) have been investigated to shed light on the nature of enzyme-mimic catalysis. They exhibit a different density of binding sites that are well arranged into the nanospace with corresponding distances of opposite binding sites. Such a structural specificity results in a facile switch in selectivity from an exclusive formation of the thermodynamically stable product to the kinetic product. Thus, the proposed targeting strategy, based on the combination of porous materials and binding events, paves a new way to develop highly efficient heterogeneous catalysts for shifting selectivity.


Assuntos
Metaloporfirinas , Metaloporfirinas/química , Espaços Confinados , Cinética , Sítios de Ligação , Catálise
9.
Small ; 19(35): e2300900, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37096928

RESUMO

Nanochannel-based confinement effect is a fascinating signal transduction strategy for high-performance sensing, but only size confinement is focused on while other confinement effects are unexplored. Here, a highly integrated nanochannel-electrodes chip (INEC) is created and a size/volume-dual-confinement enzyme catalysis model for rapid and sensitive bacteria detection is developed. The INEC, by directly sandwiching a nanochannel chip (60 µm in thickness) in nanoporous gold layers, creates a micro-droplet-based confinement electrochemical cell (CEC). The size confinement of nanochannel promotes the urease catalysis efficiency to generate more ions, while the volume confinement of CEC significantly enriches ions by restricting diffusion. As a result, the INEC-based dual-confinement effects benefit a synergetic enhancement of the catalytic signal. A 11-times ion-strength-based impedance response is obtained within just 1 min when compared to the relevant open system. Combining this novel nanoconfinement effects with nanofiltration of INEC, a separation/signal amplification-integrated sensing strategy is further developed for Salmonella typhimurium detection. The biosensor realizes facile, rapid (<20 min), and specific signal readout with a detection limit of 9 CFU mL-1 in culturing solution, superior to most reports. This work may create a new paradigm for studying nanoconfined processes and contribute a new signal transduction technique for trace analysis application.


Assuntos
Técnicas Biossensoriais , Espaços Confinados , Impedância Elétrica , Eletrodos , Salmonella , Catálise , Técnicas Biossensoriais/métodos , Técnicas Eletroquímicas
10.
Environ Sci Pollut Res Int ; 30(15): 44067-44085, 2023 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-36680724

RESUMO

Effects of indoor temperature (T∞) and relative humidity (RH∞) on the airborne transmission of sneeze droplets in a confined space were studied over the T∞ range of 15-30 °C and RH∞ of 22-62%. In addition, a theoretical evaporation model was used to estimate the droplet lifetime based on experimental data. The results showed that the body mass index (BMI) of the participants played an important role in the sneezing jet velocity, while the impact of the BMI and gender of participants was insignificant on the size distribution of droplets. At a critical relative humidity RH∞,crit of 46%, the sneezing jet velocity and droplet lifetime were roughly independent of T∞. At RH∞ < RH∞,crit, the sneezing jet velocity decreased by increasing T∞ from 15 to 30 °C, while its trend was reversed at RH∞ > RH∞,crit. The maximum spreading distance of aerosols increased by decreasing the RH∞ and increasing T∞, while the droplet lifetime increased by decreasing T∞ at RH∞ > RH∞,crit. The mean diameter of aerosolized droplets was less affected by T∞ than the large droplets at RH∞ < RH∞,crit, while the mean diameter and number fraction of aerosols were more influenced by RH∞ than the T∞ in the range of 46% ≤ RH∞ ≤ 62%. In summary, this study suggests suitable indoor environmental conditions by considering the transmission rate and lifetime of respiratory droplets to reduce the spread of COVID-19.


Assuntos
COVID-19 , Humanos , Aerossóis e Gotículas Respiratórios , Espaços Confinados , Espirro , Tamanho da Partícula
11.
Chinese Critical Care Medicine ; (12): 777-781, 2023.
Artigo em Chinês | WPRIM (Pacífico Ocidental) | ID: wpr-982674

RESUMO

Major natural disasters seriously threaten human life and health. After earthquakes and other catastrophes, survivors are often trapped in the confined spaces caused by the collapse of ground and buildings, with relative separation from the outside world, restricted access, complex environment, and oncoming or ongoing unsafety, leading to the rescue extremely difficult. In order to save lives and improve the outcome more efficiently in the confined spaces after natural disasters, it is very important to standardize and reasonably apply the trauma assessment and first aid workflow. This study focuses on trauma assessment and first aid. From the aspects of trauma assessment, vital signs stabilization, hemostasis and bandaging, post-trauma anti-infection, and the transportation of patients, a trauma first aid work process suitable for a small space of a major natural disaster is formed, It is helpful to realize the immediate and efficient treatment of trauma in the confined spaces after natural catastrophes, to reduce the rate of death and disability and improve the outcome of patients.


Assuntos
Humanos , Desastres , Primeiros Socorros , Espaços Confinados , Terremotos
12.
Chem Commun (Camb) ; 58(100): 13873-13886, 2022 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-36448362

RESUMO

Metal-organic cages (MOCs) have become an intensely studied class of abiotic host molecules. This is due to the ability to generate a myriad of polyhedral architectures from relatively simple, and minimal numbers of, components in high yield and under thermodynamic control. The encapsulation of molecular guests within the nanoscale, confined cavities of these cages frequently draws comparisons with enzymatic binding sites. In this regard, the ostensible ease with which chemical modifications can be made to these internal cavities adds to their attractiveness, as they can be readily tailored with a high degree of precision. In this Feature Article, the ways in which the cavities of MOCs can be engineered at the molecular level will be looked at. The discussion will be divided across three key parameters: size, shape and functionality. Most concepts will be exemplified with a focus on the Pd2L4 class of assemblies due to their relative structural simplicity and the wealth of studies reported in the literature. The core principles discussed will, however, be generalisable to other classes of MOCs, and abiotic host systems as a whole. Gaining increasing mastery over the fine tuning of MOC cavity properties, whilst retaining facile, high-fidelity self-assembly processes, will lead to ever more precise engineering of the cavities of artificial host systems with complex and highly specific functionality.


Assuntos
Espaços Confinados , Engenharia , Metais
13.
J Wildl Dis ; 58(4): 735-745, 2022 10 01.
Artigo em Inglês | MEDLINE | ID: mdl-36228618

RESUMO

Boma adaptation is an important component of rhinoceros translocations to allow transition to new diets, restricted space, and quarantine for disease screening. However, up to 20% of recently captured white rhinoceros (Ceratotherium simum) do not adjust to captivity, resulting in early release or even death. The causes and physiologic consequences of maladaptation to boma confinement are poorly understood. The aim of this investigation was to evaluate hematologic and serum biochemical changes in maladapted rhinoceros compared to animals that adapted under the same boma conditions. Ninety-six white rhinoceros were captured between 2009 and 2011 in Kruger National Park, South Africa and placed in bomas prior to translocation. Weight, complete blood count, and serum biochemical panel results were recorded when rhinoceros were placed in the boma and repeated on the day of release. In this study, the mean duration of boma confinement for maladapted white rhinoceros was 13 d (range 8-16 d) compared to 89.9 d (range 39-187 d) for adapted animals. Mean weight loss between capture and release was significantly greater in maladapted rhinoceros (224.0 versus 65.9 kgs; P<0.001). Although adapted rhinoceros had statistically significant changes in some hematologic and biochemical values, most were not considered clinically relevant. In contrast, the maladapted rhinoceros had significant changes at the time of early release from the boma, including evidence of leukocytosis with left shift, lymphopenia, eosinopenia, decreased red blood cell count and hematocrit, increased serum creatine kinase, and decreased serum calcium, phosphorus, and magnesium values. Along with loss of body condition, these findings were consistent with a stress-associated catabolic response. These changes occurred in the first 2 wk of confinement, and the results provide a foundation for evaluating adaptation in white rhinoceros. Future studies should focus on factors that improve adaptation and welfare of recently confined free-ranging white rhinoceros.


Assuntos
Adaptação Psicológica , Espaços Confinados , Perissodáctilos , Animais , Parques Recreativos , África do Sul/epidemiologia , Bem-Estar do Animal , Estresse Fisiológico
14.
Nat Commun ; 13(1): 6289, 2022 10 21.
Artigo em Inglês | MEDLINE | ID: mdl-36271078

RESUMO

Biological microorganisms overcome the Brownian motion at low Reynolds numbers by utilizing symmetry-breaking mechanisms. Inspired by them, various microrobot locomotion methods have been developed at the microscale by breaking the hydrodynamic symmetry. Although the boundary effects have been extensively studied for microswimmers and employed for surface-rolling microrobots, the behavior of microrobots in the proximity of multiple wall-based "confinement" is yet to be elucidated. Here, we study the confinement effect on the motion of surface-rolling microrobots. Our experiments demonstrate that the locomotion efficiency of spherical microrollers drastically decreases in confined spaces due to out-of-plane rotational flows generated during locomotion. Hence, a slender microroller design, generating smaller rotational flows, is shown to outperform spherical microrollers in confined spaces. Our results elucidate the underlying physics of surface rolling-based locomotion in confined spaces and present a design strategy with optimal flow generation for efficient propulsion in such areas, including blood vessels and microchannels.


Assuntos
Robótica , Robótica/métodos , Espaços Confinados , Movimento (Física) , Locomoção , Hidrodinâmica
15.
Artigo em Chinês | MEDLINE | ID: mdl-36052593

RESUMO

Hydrogen sulphide poisoning is an acute poisoning event that occurs frequently in summer. A case of acute hydrogen sulphide poisoning in a confined space in August 2018 was investigated and clinical data were analyzed. This is a typical case of acute hydrogen sulfide gas poisoning in a confined space. The main cause of the accident is the lack of occupational protection and illegal rescue. Among the 5 patients, 3 died, 1 patient had long-term sequelae of nervous system damage such as cortical blindness, and 1 patient was cured.


Assuntos
Intoxicação por Gás , Sulfeto de Hidrogênio , Intoxicação , Acidentes , Acidentes de Trabalho , Espaços Confinados , Humanos
16.
Behav Processes ; 201: 104712, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35905925

RESUMO

Many cats show signs of fear and stress during veterinary examinations and procedures, with environmental stimuli such as noise contributing to these responses. The objective of this study was to investigate the effect of background noise commonly heard in veterinary clinics (people talking, kennel doors shutting, dogs barking) on behavioural and physiological responses in companion cats. In Experiment 1, owned cats underwent a mock physical examination in a veterinary clinic with (n = 16) or without (n = 16) a pre-recorded noise track. A second experiment was conducted to assess cat responses to noise outside of handling and a clinic environment. In Experiment 2, shelter cats were either exposed (n = 15) or not exposed (n = 15) to the same noise track while allowed free movement in a small enclosure. Physiological and behavioural responses previously validated as negative responses in cats (e.g., indicative of fear, stress and aversion) were recorded, and outcome variables were compared between treatments. For both experiments, cats exposed to the noise track showed higher heart and respiratory rates. Noise was not associated with behavioural changes during the physical examination; however, cats who were freely moving showed more behavioural signs of fear and/or stress during noise exposure compared to the no noise conditions. These results show that high levels of background noise elicit physiological stress responses in cats, while ceiling effects of the examination and exposure to the clinic environment likely prevented treatment-related behavioral differences from being detected during the physical examination. It is recommended that those working with cats in environments with high levels of background noise limit cat exposure to these noises to reduce cat fear and stress.


Assuntos
Comportamento Animal , Espaços Confinados , Animais , Comportamento Animal/fisiologia , Gatos , Cães , Medo , Hospitais Veterinários , Humanos , Animais de Estimação
17.
Artigo em Inglês | MEDLINE | ID: mdl-35742666

RESUMO

Employee performance in terms of knowledge of job scope, safe working practices, and safety-related attitude at work are used to measure an organization's success in managing employee welfare and safety to prevent workplace injury and death. This study aims to determine the level of knowledge, attitude, and practice on safe working in confined space among water services workers. A cross-sectional study involving a randomly selected 207 water services workers working in a confined space was performed in the central region of Malaysia. The assessment was performed using a validated Malay self-administered questionnaire. Descriptive statistics, Chi-square test and Logistic regression were used for data analyses. The study's participants were all men, with a mean (SD) age of 35.2 (8.83) years. The average working duration was 10.8 years. Overall, 67.1% of participants had good knowledge, while 65.7% had a positive attitude. The majority of the workers (60.4%) were found to follow safe working practices. Regression analysis revealed that significant predictors for knowledge were age [Adjusted odds ratio (Adj. OR) 2.793; 95% CI: 1.310, 5.955; p = 0.008] and attitude (Adj. OR 2.127; 95% CI: 1.011, 4.526; p = 0.048). Attitude was influenced by marital status (Adj. OR 4.126; 95% CI: 2.079, 8.186; p < 0.001) and knowledge level (Adj. OR 2.224; 95% CI: 1.025, 4.824; p = 0.043). A positive attitude was the sole predictor influencing the safe practice (Adj. OR; 1.878; 95% CI: 1.041, 3.388; p = 0.036). In conclusion, the workers' levels of knowledge, attitudes, and practices were relatively satisfactory. Extensive investment in workplace safety and health programs, appropriate training, growth opportunities, and effective employee performance evaluation methodologies may assist workers in performing at their best.


Assuntos
Espaços Confinados , Conhecimentos, Atitudes e Prática em Saúde , Adulto , Estudos Transversais , Humanos , Malásia , Masculino , Inquéritos e Questionários , Água
18.
Cell Syst ; 13(7): 514-529.e10, 2022 07 20.
Artigo em Inglês | MEDLINE | ID: mdl-35679858

RESUMO

Navigation through a dense, physically confining extracellular matrix is common in invasive cell spread and tissue reorganization but is still poorly understood. Here, we show that this migration is mediated by cyclic changes in the activity of a small GTPase RhoA, which is dependent on the oscillatory changes in the activity and abundance of the RhoA guanine nucleotide exchange factor, GEF-H1, and triggered by a persistent increase in the intracellular Ca2+ levels. We show that the molecular clock driving these cyclic changes is mediated by two coupled negative feedback loops, dependent on the microtubule dynamics, with a frequency that can be experimentally modulated based on a predictive mathematical model. We further demonstrate that an increasing frequency of the clock translates into a faster cell migration within physically confining spaces. This work lays the foundation for a better understanding of the molecular mechanisms dynamically driving cell migration in complex environments.


Assuntos
Espaços Confinados , Microtúbulos , Movimento Celular/genética , Fatores de Troca de Nucleotídeo Guanina Rho
19.
Biophys J ; 121(13): 2653-2662, 2022 07 05.
Artigo em Inglês | MEDLINE | ID: mdl-35398019

RESUMO

Symbiotic bacteria often navigate complex environments before colonizing privileged sites in their host organism. Chemical gradients are known to facilitate directional taxis of these bacteria, guiding them toward their eventual destination. However, less is known about the role of physical features in shaping the path the bacteria take and defining how they traverse a given space. The flagellated marine bacterium Vibrio fischeri, which forms a binary symbiosis with the Hawaiian bobtail squid, Euprymna scolopes, must navigate tight physical confinement during colonization, squeezing through a tissue bottleneck constricting to ∼2 µm in width on the way to its eventual home. Using microfluidic in vitro experiments, we discovered that V. fischeri cells alter their behavior upon entry into confined space, straightening their swimming paths and promoting escape from confinement. Using a computational model, we attributed this escape response to two factors: reduced directional fluctuation and a refractory period between reversals. Additional experiments in asymmetric capillary tubes confirmed that V. fischeri quickly escape from confined ends, even when drawn into the ends by chemoattraction. This avoidance was apparent down to a limit of confinement approaching the diameter of the cell itself, resulting in a balance between chemoattraction and evasion of physical confinement. Our findings demonstrate that nontrivial distributions of swimming bacteria can emerge from simple physical gradients in the level of confinement. Tight spaces may serve as an additional, crucial cue for bacteria while they navigate complex environments to enter specific habitats.


Assuntos
Espaços Confinados , Natação , Aliivibrio fischeri/fisiologia , Animais , Decapodiformes/microbiologia , Decapodiformes/fisiologia , Simbiose/fisiologia
20.
J Agric Saf Health ; 28(1): 65-81, 2022 Jan 13.
Artigo em Inglês | MEDLINE | ID: mdl-35130589

RESUMO

HIGHLIGHTS: Approximately ten cases were documented annually over the 44-year period; 48% were in the last decade and 28% were in the last three years, primarily due to more aggressive surveillance and on-line access to incident reports. A total of 389 incidents involving 459 individuals were documented, of which 59% were fatal; >85% of the victims were male, with an average age of 37. 49 rescue incidents involved a total of 119 secondary victims, indicating that approximately 26% of the victims were secondary victims, including first responders. 20% of all victims, when age was known, were children or youth under the age of 21. ABSTRACT: There is limited published research exploring the frequency and causes of livestock waste-related fatalities and injuries among farm operators and workers. While there has been ongoing surveillance of mortality and morbidity involving agricultural confined space-related incidents, such as grain storage facilities, few resources have been invested in estimating the frequency of livestock waste-related incidents, which are often reported as primarily involving confined spaces. Existing surveillance efforts have historically underreported fatal cases, injuries, and near misses and misclassified these incidents as non-farm related. For nearly 40 years, the Purdue Agricultural Confined Spaces Incident Database (PACSID) has been used to document agricultural confined space-related incidents, of which manure storage and handling activities have accounted for 22% of the cases documented. The specific goal of this study was to address the gap in the current understanding of the frequency and severity of injuries associated with livestock waste storage, handling, and transport by: (1) developing a consistent way to identify, document, and code these cases; (2) summarizing all known U.S. cases, both fatal and non-fatal, currently documented in the PACSID; (3) identifying the most significant risks contributing to livestock waste storage, handling, and transport-related incidents; and (4) providing evidence-based recommendations and mitigation strategies to enhance the effectiveness of current injury prevention measures. The PACSID and other sources were mined for relevant data, and an aggressive effort was made to document additional cases through a variety of surveillance methods. A total of 459 individual U.S. cases from the study period (1975 to 2019) were identified, coded using a uniform coding system, and summarized. Overall, cases were documented in 43 states, with 66% (302 cases) documented in heavily agricultural and, more specifically, historically strong dairy production states. Of the cases reviewed, 59% were fatal, males ages 21 to 30 and dairy farm workers were identified as high-risk populations, 20% were identified as under the age of 21, and 49 incidents involved multiple victims. Farm injury data limitations and underreporting were problematic, especially during the early years of the study period. However, the findings provide a foundation for recommending safer workplace safety and health practices, evaluating existing engineering and regulatory standards, assessing the impacts of current injury prevention efforts, and redesigning farm safety programs, especially those targeting livestock workers, to reduce the frequency and severity of these incidents.


Assuntos
Gado , Ferimentos e Lesões , Acidentes de Trabalho , Adolescente , Adulto , Agricultura , Animais , Criança , Espaços Confinados , Fazendas , Humanos , Masculino , Ferimentos e Lesões/epidemiologia , Adulto Jovem
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