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1.
Cell ; 184(26): 6313-6325.e18, 2021 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-34942099

RESUMO

How tissues acquire complex shapes is a fundamental question in biology and regenerative medicine. Zebrafish semicircular canals form from invaginations in the otic epithelium (buds) that extend and fuse to form the hubs of each canal. We find that conventional actomyosin-driven behaviors are not required. Instead, local secretion of hyaluronan, made by the enzymes uridine 5'-diphosphate dehydrogenase (ugdh) and hyaluronan synthase 3 (has3), drives canal morphogenesis. Charged hyaluronate polymers osmotically swell with water and generate isotropic extracellular pressure to deform the overlying epithelium into buds. The mechanical anisotropy needed to shape buds into tubes is conferred by a polarized distribution of actomyosin and E-cadherin-rich membrane tethers, which we term cytocinches. Most work on tissue morphogenesis ascribes actomyosin contractility as the driving force, while the extracellular matrix shapes tissues through differential stiffness. Our work inverts this expectation. Hyaluronate pressure shaped by anisotropic tissue stiffness may be a widespread mechanism for powering morphological change in organogenesis and tissue engineering.


Assuntos
Espaço Extracelular/química , Ácido Hialurônico/farmacologia , Morfogênese , Especificidade de Órgãos , Pressão , Canais Semicirculares/citologia , Canais Semicirculares/embriologia , Actomiosina/metabolismo , Animais , Anisotropia , Comportamento Animal , Matriz Extracelular/metabolismo , Ácido Hialurônico/biossíntese , Modelos Biológicos , Morfogênese/efeitos dos fármacos , Especificidade de Órgãos/efeitos dos fármacos , Pressão Osmótica , Canais Semicirculares/diagnóstico por imagem , Comportamento Estereotipado , Peixe-Zebra/embriologia , Proteínas de Peixe-Zebra/metabolismo
2.
Nature ; 631(8019): 118-124, 2024 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-38898274

RESUMO

Locating sound sources such as prey or predators is critical for survival in many vertebrates. Terrestrial vertebrates locate sources by measuring the time delay and intensity difference of sound pressure at each ear1-5. Underwater, however, the physics of sound makes interaural cues very small, suggesting that directional hearing in fish should be nearly impossible6. Yet, directional hearing has been confirmed behaviourally, although the mechanisms have remained unknown for decades. Several hypotheses have been proposed to explain this remarkable ability, including the possibility that fish evolved an extreme sensitivity to minute interaural differences or that fish might compare sound pressure with particle motion signals7,8. However, experimental challenges have long hindered a definitive explanation. Here we empirically test these models in the transparent teleost Danionella cerebrum, one of the smallest vertebrates9,10. By selectively controlling pressure and particle motion, we dissect the sensory algorithm underlying directional acoustic startles. We find that both cues are indispensable for this behaviour and that their relative phase controls its direction. Using micro-computed tomography and optical vibrometry, we further show that D. cerebrum has the sensory structures to implement this mechanism. D. cerebrum shares these structures with more than 15% of living vertebrate species, suggesting a widespread mechanism for inferring sound direction.


Assuntos
Sinais (Psicologia) , Cyprinidae , Audição , Localização de Som , Animais , Feminino , Masculino , Algoritmos , Audição/fisiologia , Pressão , Som , Localização de Som/fisiologia , Vibração , Microtomografia por Raio-X , Cyprinidae/fisiologia , Movimento (Física) , Reflexo de Sobressalto , Material Particulado
3.
Nature ; 623(7988): 842-852, 2023 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-37853127

RESUMO

Optimum protein function and biochemical activity critically depends on water availability because solvent thermodynamics drive protein folding and macromolecular interactions1. Reciprocally, macromolecules restrict the movement of 'structured' water molecules within their hydration layers, reducing the available 'free' bulk solvent and therefore the total thermodynamic potential energy of water, or water potential. Here, within concentrated macromolecular solutions such as the cytosol, we found that modest changes in temperature greatly affect the water potential, and are counteracted by opposing changes in osmotic strength. This duality of temperature and osmotic strength enables simple manipulations of solvent thermodynamics to prevent cell death after extreme cold or heat shock. Physiologically, cells must sustain their activity against fluctuating temperature, pressure and osmotic strength, which impact water availability within seconds. Yet, established mechanisms of water homeostasis act over much slower timescales2,3; we therefore postulated the existence of a rapid compensatory response. We find that this function is performed by water potential-driven changes in macromolecular assembly, particularly biomolecular condensation of intrinsically disordered proteins. The formation and dissolution of biomolecular condensates liberates and captures free water, respectively, quickly counteracting thermal or osmotic perturbations of water potential, which is consequently robustly buffered in the cytoplasm. Our results indicate that biomolecular condensation constitutes an intrinsic biophysical feedback response that rapidly compensates for intracellular osmotic and thermal fluctuations. We suggest that preserving water availability within the concentrated cytosol is an overlooked evolutionary driver of protein (dis)order and function.


Assuntos
Substâncias Macromoleculares , Proteínas , Solventes , Termodinâmica , Água , Morte Celular , Citosol/química , Citosol/metabolismo , Homeostase , Substâncias Macromoleculares/química , Substâncias Macromoleculares/metabolismo , Concentração Osmolar , Pressão , Proteínas/química , Proteínas/metabolismo , Solventes/química , Solventes/metabolismo , Temperatura , Fatores de Tempo , Água/química , Água/metabolismo
4.
Nature ; 596(7871): 238-243, 2021 08.
Artigo em Inglês | MEDLINE | ID: mdl-34381233

RESUMO

Structured fabrics, such as woven sheets or chain mail armours, derive their properties both from the constitutive materials and their geometry1,2. Their design can target desirable characteristics, such as high impact resistance, thermal regulation, or electrical conductivity3-5. Once realized, however, the fabrics' properties are usually fixed. Here we demonstrate structured fabrics with tunable bending modulus, consisting of three-dimensional particles arranged into layered chain mails. The chain mails conform to complex shapes2, but when pressure is exerted at their boundaries, the particles interlock and the chain mails jam. We show that, with small external pressure (about 93 kilopascals), the sheets become more than 25 times stiffer than in their relaxed configuration. This dramatic increase in bending resistance arises because the interlocking particles have high tensile resistance, unlike what is found for loose granular media. We use discrete-element simulations to relate the chain mail's micro-structure to macroscale properties and to interpret experimental measurements. We find that chain mails, consisting of different non-convex granular particles, undergo a jamming phase transition that is described by a characteristic power-law function akin to the behaviour of conventional convex media. Our work provides routes towards lightweight, tunable and adaptive fabrics, with potential applications in wearable exoskeletons, haptic architectures and reconfigurable medical supports.


Assuntos
Fenômenos Mecânicos , Têxteis , Exoesqueleto Energizado , Humanos , Maleabilidade , Pressão , Resistência à Tração , Dispositivos Eletrônicos Vestíveis
5.
Proc Natl Acad Sci U S A ; 121(34): e2405628121, 2024 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-39141355

RESUMO

Fluorescence guidance is routinely used in surgery to enhance perfusion contrast in multiple types of diseases. Pressure-enhanced sensing of tissue oxygenation (PRESTO) via fluorescence is a technique extensively analyzed here, that uses an FDA-approved human precursor molecule, 5-aminolevulinic acid (ALA), to stimulate a unique delayed fluorescence signal that is representative of tissue hypoxia. The ALA precontrast agent is metabolized in most tissues into a red fluorescent molecule, protoporphyrin IX (PpIX), which has both prompt fluorescence, indicative of the concentration, and a delayed fluorescence, that is amplified in low tissue oxygen situations. Applied pressure from palpation induces transient capillary stasis and a resulting transient PRESTO contrast, dominant when there is near hypoxia. This study examined the kinetics and behavior of this effect in both normal and tumor tissues, with a prolonged high PRESTO contrast (contrast to background of 7.3) across 5 tumor models, due to sluggish capillaries and inhibited vasodynamics. This tissue function imaging approach is a fundamentally unique tool for real-time palpation-induced tissue response in vivo, relevant for chronic hypoxia, such as vascular diseases or oncologic surgery.


Assuntos
Ácido Aminolevulínico , Neoplasias , Oxigênio , Protoporfirinas , Animais , Oxigênio/metabolismo , Camundongos , Ácido Aminolevulínico/metabolismo , Neoplasias/metabolismo , Neoplasias/cirurgia , Protoporfirinas/metabolismo , Humanos , Pressão , Porfirinas/metabolismo
6.
Proc Natl Acad Sci U S A ; 121(22): e2319880121, 2024 May 28.
Artigo em Inglês | MEDLINE | ID: mdl-38768353

RESUMO

Elevated interstitial fluid pressure (IFP) within pathological tissues (e.g., tumors, obstructed kidneys, and cirrhotic livers) creates a significant hindrance to the transport of nanomedicine, ultimately impairing the therapeutic efficiency. Among these tissues, solid tumors present the most challenging scenario. While several strategies through reducing tumor IFP have been devised to enhance nanoparticle delivery, few approaches focus on modulating the intrinsic properties of nanoparticles to effectively counteract IFP during extravasation and penetration, which are precisely the stages obstructed by elevated IFP. Herein, we propose an innovative solution by engineering nanoparticles with a fusiform shape of high curvature, enabling efficient surmounting of IFP barriers during extravasation and penetration within tumor tissues. Through experimental and theoretical analyses, we demonstrate that the elongated nanoparticles with the highest mean curvature outperform spherical and rod-shaped counterparts against elevated IFP, leading to superior intratumoral accumulation and antitumor efficacy. Super-resolution microscopy and molecular dynamics simulations uncover the underlying mechanisms in which the high curvature contributes to diminished drag force in surmounting high-pressure differentials during extravasation. Simultaneously, the facilitated rotational movement augments the hopping frequency during penetration. This study effectively addresses the limitations posed by high-pressure impediments, uncovers the mutual interactions between the physical properties of NPs and their environment, and presents a promising avenue for advancing cancer treatment through nanomedicine.


Assuntos
Sistemas de Liberação de Medicamentos , Líquido Extracelular , Nanopartículas , Pressão , Nanopartículas/química , Líquido Extracelular/metabolismo , Animais , Sistemas de Liberação de Medicamentos/métodos , Camundongos , Humanos , Neoplasias/tratamento farmacológico , Neoplasias/metabolismo , Linhagem Celular Tumoral , Extravasamento de Materiais Terapêuticos e Diagnósticos , Simulação de Dinâmica Molecular , Antineoplásicos/farmacocinética , Antineoplásicos/administração & dosagem , Antineoplásicos/química
7.
J Cell Sci ; 137(12)2024 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-38832512

RESUMO

As cells migrate through biological tissues, they must frequently squeeze through micron-sized constrictions in the form of interstitial pores between extracellular matrix fibers and/or other cells. Although it is now well recognized that such confined migration is limited by the nucleus, which is the largest and stiffest organelle, it remains incompletely understood how cells apply sufficient force to move their nucleus through small constrictions. Here, we report a mechanism by which contraction of the cell rear cortex pushes the nucleus forward to mediate nuclear transit through constrictions. Laser ablation of the rear cortex reveals that pushing forces behind the nucleus are the result of increased intracellular pressure in the rear compartment of the cell. The pushing forces behind the nucleus depend on accumulation of actomyosin in the rear cortex and require Rho kinase (ROCK) activity. Collectively, our results suggest a mechanism by which cells generate elevated intracellular pressure in the posterior compartment to facilitate nuclear transit through three-dimensional (3D) constrictions. This mechanism might supplement or even substitute for other mechanisms supporting nuclear transit, ensuring robust cell migrations in confined 3D environments.


Assuntos
Movimento Celular , Núcleo Celular , Núcleo Celular/metabolismo , Movimento Celular/fisiologia , Humanos , Actomiosina/metabolismo , Quinases Associadas a rho/metabolismo , Animais , Pressão , Camundongos
8.
Nature ; 588(7837): 290-295, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33057202

RESUMO

Henry Miller stated that "to relieve a full bladder is one of the great human joys". Urination is critically important in health and ailments of the lower urinary tract cause high pathological burden. Although there have been advances in understanding the central circuitry in the brain that facilitates urination1-3, there is a lack of in-depth mechanistic insight into the process. In addition to central control, micturition reflexes that govern urination are all initiated by peripheral mechanical stimuli such as bladder stretch and urethral flow4. The mechanotransduction molecules and cell types that function as the primary stretch and pressure detectors in the urinary tract mostly remain unknown. Here we identify expression of the mechanosensitive ion channel PIEZO2 in lower urinary tract tissues, where it is required for low-threshold bladder-stretch sensing and urethral micturition reflexes. We show that PIEZO2 acts as a sensor in both the bladder urothelium and innervating sensory neurons. Humans and mice lacking functional PIEZO2 have impaired bladder control, and humans lacking functional PIEZO2 report deficient bladder-filling sensation. This study identifies PIEZO2 as a key mechanosensor in urinary function. These findings set the foundation for future work to identify the interactions between urothelial cells and sensory neurons that control urination.


Assuntos
Canais Iônicos/metabolismo , Mecanotransdução Celular/fisiologia , Células Receptoras Sensoriais/metabolismo , Bexiga Urinária/inervação , Bexiga Urinária/fisiologia , Micção/fisiologia , Urotélio/citologia , Animais , Feminino , Humanos , Canais Iônicos/deficiência , Camundongos , Pressão , Reflexo/fisiologia , Bexiga Urinária/citologia , Bexiga Urinária/fisiopatologia , Sistema Urinário/inervação , Sistema Urinário/metabolismo , Urotélio/metabolismo
9.
Proc Natl Acad Sci U S A ; 120(14): e2220270120, 2023 04 04.
Artigo em Inglês | MEDLINE | ID: mdl-36972429

RESUMO

Control of carbon dioxide and water vapor exchange between a leaf's interior and the surrounding air is accomplished by variations in the turgor pressures in the small epidermal and guard cells that cover the leaf's surface. These pressures respond to changes in light intensity and wavelength, temperature, CO2 concentration, and air humidity. The dynamical equations that describe such processes are formally identical to those that define computation in a two-layer, adaptive, cellular nonlinear network. This exact identification suggests that leaf gas-exchange processes can be understood as analog computation and that exploiting the output of two-layer, adaptive, cellular nonlinear networks might provide new tools in applied plant research.


Assuntos
Folhas de Planta , Estômatos de Plantas , Luz , Pressão , Dióxido de Carbono
10.
J Biol Chem ; 300(4): 107156, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38479601

RESUMO

Mechanically activated Piezo1 channels undergo transitions from closed to open-state in response to pressure and other mechanical stimuli. However, the molecular details of these mechanosensitive gating transitions are unknown. Here, we used cell-attached pressure-clamp recordings to acquire single channel data at steady-state conditions (where inactivation has settled down), at various pressures and voltages. Importantly, we identify and analyze subconductance states of the channel which were not reported before. Pressure-dependent activation of Piezo1 increases the occupancy of open and subconductance state at the expense of decreased occupancy of shut-states. No significant change in the mean open time of subconductance states was observed with increasing negative pipette pressure or with varying voltages (ranging from -40 to -100 mV). Using Markov-chain modeling, we identified a minimal four-states kinetic scheme, which recapitulates essential characteristics of the single channel data, including that of the subconductance level. This study advances our understanding of Piezo1-gating mechanism in response to discrete stimuli (such as pressure and voltage) and paves the path to develop cellular and tissue level models to predict Piezo1 function in various cell types.


Assuntos
Ativação do Canal Iônico , Canais Iônicos , Mecanotransdução Celular , Pressão , Humanos , Células HEK293 , Ativação do Canal Iônico/fisiologia , Canais Iônicos/metabolismo , Cinética , Cadeias de Markov
11.
Nature ; 573(7775): 558-562, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31554980

RESUMO

High-pressure transitions are thought to modify hydrogen molecules to a molecular metallic solid and finally to an atomic metal1, which is predicted to have exotic physical properties and the topology of a two-component (electron and proton) superconducting superfluid condensate2,3. Therefore, understanding such transitions remains an important objective in condensed matter physics4,5. However, measurements of the crystal structure of solid hydrogen, which provides crucial information about the metallization of hydrogen under compression, are lacking for most high-pressure phases, owing to the considerable technical challenges involved in X-ray and neutron diffraction measurements under extreme conditions. Here we present a single-crystal X-ray diffraction study of solid hydrogen at pressures of up to 254 gigapascals that reveals the crystallographic nature of the transitions from phase I to phases III and IV. Under compression, hydrogen molecules remain in the hexagonal close-packed (hcp) crystal lattice structure, accompanied by a monotonic increase in anisotropy. In addition, the pressure-dependent decrease of the unit cell volume exhibits a slope change when entering phase IV, suggesting a second-order isostructural phase transition. Our results indicate that the precursor to the exotic two-component atomic hydrogen may consist of electronic transitions caused by a highly distorted hcp Brillouin zone and molecular-symmetry breaking.


Assuntos
Hidrogênio/química , Modelos Moleculares , Pressão , Eletrônica , Difração de Nêutrons , Transição de Fase , Difração de Raios X
13.
Nature ; 571(7764): 261-264, 2019 07.
Artigo em Inglês | MEDLINE | ID: mdl-31243365

RESUMO

Until relatively recently, humans, similar to other animals, were habitually barefoot. Therefore, the soles of our feet were the only direct contact between the body and the ground when walking. There is indirect evidence that footwear such as sandals and moccasins were first invented within the past 40 thousand years1, the oldest recovered footwear dates to eight thousand years ago2 and inexpensive shoes with cushioned heels were not developed until the Industrial Revolution3. Because calluses-thickened and hardened areas of the epidermal layer of the skin-are the evolutionary solution to protecting the foot, we wondered whether they differ from shoes in maintaining tactile sensitivity during walking, especially at initial foot contact, to improve safety on surfaces that can be slippery, abrasive or otherwise injurious or uncomfortable. Here we show that, as expected, people from Kenya and the United States who frequently walk barefoot have thicker and harder calluses than those who typically use footwear. However, in contrast to shoes, callus thickness does not trade-off protection, measured as hardness and stiffness, for the ability to perceive tactile stimuli at frequencies experienced during walking. Additionally, unlike cushioned footwear, callus thickness does not affect how hard the feet strike the ground during walking, as indicated by impact forces. Along with providing protection and comfort at the cost of tactile sensitivity, cushioned footwear also lowers rates of loading at impact but increases force impulses, with unknown effects on the skeleton that merit future study.


Assuntos
Calosidades/fisiopatologia , Pé/patologia , Pé/fisiologia , Dor/fisiopatologia , Tato/fisiologia , Caminhada/fisiologia , Adulto , Boston , Calosidades/patologia , Feminino , Fricção/fisiologia , Dureza/fisiologia , Humanos , Quênia , Masculino , Pessoa de Meia-Idade , Estimulação Física , Pressão , Sapatos , Fenômenos Fisiológicos da Pele , Suporte de Carga/fisiologia , Adulto Jovem
14.
Nature ; 566(7743): 264-269, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30700906

RESUMO

The mechanistic target of rapamycin complex-1 (mTORC1) coordinates regulation of growth, metabolism, protein synthesis and autophagy1. Its hyperactivation contributes to disease in numerous organs, including the heart1,2, although broad inhibition of mTORC1 risks interference with its homeostatic roles. Tuberin (TSC2) is a GTPase-activating protein and prominent intrinsic regulator of mTORC1 that acts through modulation of RHEB (Ras homologue enriched in brain). TSC2 constitutively inhibits mTORC1; however, this activity is modified by phosphorylation from multiple signalling kinases that in turn inhibits (AMPK and GSK-3ß) or stimulates (AKT, ERK and RSK-1) mTORC1 activity3-9. Each kinase requires engagement of multiple serines, impeding analysis of their role in vivo. Here we show that phosphorylation or gain- or loss-of-function mutations at either of two adjacent serine residues in TSC2 (S1365 and S1366 in mice; S1364 and S1365 in humans) can bidirectionally control mTORC1 activity stimulated by growth factors or haemodynamic stress, and consequently modulate cell growth and autophagy. However, basal mTORC1 activity remains unchanged. In the heart, or in isolated cardiomyocytes or fibroblasts, protein kinase G1 (PKG1) phosphorylates these TSC2 sites. PKG1 is a primary effector of nitric oxide and natriuretic peptide signalling, and protects against heart disease10-13. Suppression of hypertrophy and stimulation of autophagy in cardiomyocytes by PKG1 requires TSC2 phosphorylation. Homozygous knock-in mice that express a phosphorylation-silencing mutation in TSC2 (TSC2(S1365A)) develop worse heart disease and have higher mortality after sustained pressure overload of the heart, owing to mTORC1 hyperactivity that cannot be rescued by PKG1 stimulation. However, cardiac disease is reduced and survival of heterozygote Tsc2S1365A knock-in mice subjected to the same stress is improved by PKG1 activation or expression of a phosphorylation-mimicking mutation (TSC2(S1365E)). Resting mTORC1 activity is not altered in either knock-in model. Therefore, TSC2 phosphorylation is both required and sufficient for PKG1-mediated cardiac protection against pressure overload. The serine residues identified here provide a genetic tool for bidirectional regulation of the amplitude of stress-stimulated mTORC1 activity.


Assuntos
Proteínas Quinases Dependentes de GMP Cíclico/metabolismo , Cardiopatias/prevenção & controle , Cardiopatias/fisiopatologia , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Proteína 2 do Complexo Esclerose Tuberosa/química , Proteína 2 do Complexo Esclerose Tuberosa/metabolismo , Animais , Autofagia , Células Cultivadas , Progressão da Doença , Ativação Enzimática , Everolimo/farmacologia , Feminino , Técnicas de Introdução de Genes , Células HEK293 , Cardiopatias/genética , Cardiopatias/patologia , Humanos , Hipertrofia/tratamento farmacológico , Hipertrofia/patologia , Masculino , Alvo Mecanístico do Complexo 1 de Rapamicina/antagonistas & inibidores , Camundongos , Mutação , Miócitos Cardíacos/patologia , Fosforilação , Fosfosserina/metabolismo , Pressão , Ratos , Ratos Wistar , Serina/genética , Serina/metabolismo , Proteína 2 do Complexo Esclerose Tuberosa/genética
15.
Nano Lett ; 24(23): 7125-7133, 2024 Jun 12.
Artigo em Inglês | MEDLINE | ID: mdl-38808683

RESUMO

Wearable sensors are experiencing vibrant growth in the fields of health monitoring systems and human motion detection, with comfort becoming a significant research direction for wearable sensing devices. However, the weak moisture-wicking capability of sensor materials leads to liquid retention, severely restricting the comfort of the wearable sensors. This study employs a pattern-guided alignment strategy to construct microhill arrays, endowing triboelectric materials with directional moisture-wicking capability. Within 2.25 s, triboelectric materials can quickly and directionally remove the droplets, driven by the Laplace pressure differences and the wettability gradient. The directional moisture-wicking triboelectric materials exhibit excellent pressure sensing performance, enabling rapid response/recovery (29.1/37.0 ms), thereby achieving real-time online monitoring of human respiration and movement states. This work addresses the long-standing challenge of insufficient moisture-wicking driving force in flexible electronic sensing materials, holding significant implications for enhancing the comfort and application potential of electronic skin and wearable electronic devices.


Assuntos
Pressão , Dispositivos Eletrônicos Vestíveis , Molhabilidade , Humanos , Desenho de Equipamento
16.
Circulation ; 148(23): 1847-1856, 2023 12 05.
Artigo em Inglês | MEDLINE | ID: mdl-37952192

RESUMO

BACKGROUND: Few studies have measured ventilation during early cardiopulmonary resuscitation (CPR) before advanced airway placement. Resuscitation guidelines recommend pauses after every 30 chest compressions to deliver ventilations. The effectiveness of bag-valve-mask ventilation delivered during the pause in chest compressions is unknown. We sought to determine: (1) the incidence of lung inflation with bag-valve-mask ventilation during 30:2 CPR; and (2) the association of ventilation with outcomes after out-of-hospital cardiac arrest. METHODS: We studied patients with out-of-hospital cardiac arrest from 6 sites of the Resuscitation Outcomes Consortium CCC study (Trial of Continuous Compressions versus Standard CPR in Patients with Out-of-Hospital Cardiac Arrest). We analyzed patients assigned to the 30:2 CPR arm with ≥2 minutes of thoracic bioimpedance signal recorded with a cardiac defibrillator/monitor. Detectable ventilation waveforms were defined as having a bioimpedance amplitude ≥0.5 Ω (corresponding to ≥250 mL VT) and a duration ≥1 s. We defined a chest compression pause as a 3- to 15-s break in chest compressions. We compared the incidence of ventilation and outcomes in 2 groups: patients with ventilation waveforms in <50% of pauses (group 1) versus those with waveforms in ≥50% of pauses (group 2). RESULTS: Among 1976 patients, the mean age was 65 years; 66% were male. From the start of chest compressions until advanced airway placement, mean±SD duration of 30:2 CPR was 9.8±4.9 minutes. During this period, we identified 26 861 pauses in chest compressions; 60% of patients had ventilation waveforms in <50% of pauses (group 1, n=1177), and 40% had waveforms in ≥50% of pauses (group 2, n=799). Group 1 had a median of 12 pauses and 2 ventilations per patient versus group 2, which had 12 pauses and 12 ventilations per patient. Group 2 had higher rates of prehospital return of spontaneous circulation (40.7% versus 25.2%; P<0.0001), survival to hospital discharge (13.5% versus 4.1%; P<0.0001), and survival with favorable neurological outcome (10.6% versus 2.4%; P<0.0001). These associations persisted after adjustment for confounders. CONCLUSIONS: In this study, lung inflation occurred infrequently with bag-valve-mask ventilation during 30:2 CPR. Lung inflation in ≥50% of pauses was associated with improved return of spontaneous circulation, survival, and survival with favorable neurological outcome.


Assuntos
Reanimação Cardiopulmonar , Parada Cardíaca Extra-Hospitalar , Humanos , Masculino , Idoso , Feminino , Parada Cardíaca Extra-Hospitalar/terapia , Respiração Artificial/efeitos adversos , Pressão , Tórax
17.
Pflugers Arch ; 476(8): 1235-1247, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38856775

RESUMO

To assess the possible interactions between the dorsolateral periaqueductal gray matter (dlPAG) and the different domains of the nucleus ambiguus (nA), we have examined the pattern of double-staining c-Fos/FoxP2 protein immunoreactivity (c-Fos-ir/FoxP2-ir) and tyrosine hydroxylase (TH) throughout the rostrocaudal extent of nA in spontaneously breathing anaesthetised male Sprague-Dawley rats during dlPAG electrical stimulation. Activation of the dlPAG elicited a selective increase in c-Fos-ir with an ipsilateral predominance in the somatas of the loose (p < 0.05) and compact formation (p < 0.01) within the nA and confirmed the expression of FoxP2 bilaterally in all the domains within the nA. A second group of experiments was made to examine the importance of the dlPAG in modulating the laryngeal response evoked after electrical or chemical (glutamate) dlPAG stimulations. Both electrical and chemical stimulations evoked a significant decrease in laryngeal resistance (subglottal pressure) (p < 0.001) accompanied with an increase in respiratory rate together with a pressor and tachycardic response. The results of our study contribute to new data on the role of the mesencephalic neuronal circuits in the control mechanisms of subglottic pressure and laryngeal activity.


Assuntos
Estimulação Elétrica , Laringe , Substância Cinzenta Periaquedutal , Proteínas Proto-Oncogênicas c-fos , Ratos Sprague-Dawley , Animais , Masculino , Ratos , Substância Cinzenta Periaquedutal/metabolismo , Substância Cinzenta Periaquedutal/fisiologia , Estimulação Elétrica/métodos , Proteínas Proto-Oncogênicas c-fos/metabolismo , Laringe/fisiologia , Laringe/metabolismo , Fatores de Transcrição Forkhead/metabolismo , Tirosina 3-Mono-Oxigenase/metabolismo , Pressão , Bulbo/metabolismo , Bulbo/fisiologia , Ácido Glutâmico/metabolismo
18.
Am J Physiol Lung Cell Mol Physiol ; 327(2): L203-L217, 2024 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-38771135

RESUMO

This study investigated the relationship between three respiratory support approaches on lung volume recruitment during the first 2 h of postnatal life in preterm lambs. We estimated changes in lung aeration, measuring respiratory resistance and reactance by oscillometry at 5 Hz. We also measured intratracheal pressure in subsets of lambs. The first main finding is that sustained inflation (SI) applied noninvasively (Mask SI; n = 7) or invasively [endotracheal tube (ETT) SI; n = 6] led to similar rapid lung volume recruitment (∼6 min). In contrast, Mask continuous positive airway pressure (CPAP) without SI (n = 6) resuscitation took longer (∼30-45 min) to reach similar lung volume recruitment. The second main finding is that, in the first 15 min of postnatal life, the Mask CPAP without SI group closed their larynx during custom ventilator-driven expiration, leading to intratracheal positive end-expiratory pressure of ∼17 cmH2O (instead of 8 cmH2O provided by the ventilator). In contrast, the Mask SI group used the larynx to limit inspiratory pressure to ∼26 cmH2O (instead of 30 cmH2O provided by the ventilator). These different responses affected tidal volume, being larger in the Mask CPAP without SI group [8.4 mL/kg; 6.7-9.3 interquartile range (IQR)] compared to the Mask SI (5.0 mL/kg; 4.4-5.2 IQR) and ETT SI groups (3.3 mL/kg; 2.6-3.7 IQR). Distinct physiological responses suggest that spontaneous respiratory activity of the larynx of preterm lambs at birth can uncouple pressure applied by the ventilator to that applied to the lung, leading to unpredictable lung pressure and tidal volume delivery independently from the ventilator settings.NEW & NOTEWORTHY We compared invasive and noninvasive resuscitation on lambs at birth, including or not sustained inflation (SI). Lung volume recruitment was faster in those receiving SI. During noninvasive resuscitation, larynx modulation reduced tracheal pressure from that applied to the mask in lambs receiving SI, while it led to increased auto-positive end-expiratory pressure and very large tidal volumes in lambs not receiving SI. Our results highlight the need for individualizing pressures and monitoring tidal volumes during resuscitation at birth.


Assuntos
Animais Recém-Nascidos , Pulmão , Volume de Ventilação Pulmonar , Traqueia , Animais , Volume de Ventilação Pulmonar/fisiologia , Ovinos , Pulmão/fisiologia , Traqueia/fisiologia , Mecânica Respiratória/fisiologia , Pressão Positiva Contínua nas Vias Aéreas/métodos , Ressuscitação/métodos , Intubação Intratraqueal/métodos , Pressão , Respiração com Pressão Positiva/métodos
19.
Anal Chem ; 96(37): 15074-15080, 2024 Sep 17.
Artigo em Inglês | MEDLINE | ID: mdl-39215695

RESUMO

Multimodal immunochromatographic sensors (ICSs) have acquired extensive attention since they not only provide reliable results by comparing the different output signals but also flexibly respond to various application environments. Herein, an ICS with triple signal outputs including colorimetry, temperature, and pressure was developed for sensitive detection of chlorothalonil. The multivalent Pt/Ti3C2Tx nanoparticles as signal tags were facilely synthesized by loading PtNPs onto single-layer Ti3C2Tx nanosheets with high surface area. The acquired Pt/Ti3C2TxNPs accelerated the rate-limiting step of the aerogenesis reaction of H2O2 for producing intensive pressure signals due to their significant catalase-mimic activity. Meanwhile, they showed desirable photothermal conversion efficiency in the near-infrared region for producing significant temperature signals. Furthermore, their deep color also allowed facile colorimetry by using the naked eye. Based on a competitive immunoassay, chlorothalonil was detected as a model analyte on this trimodal ICS platform. The detection limits for pressure, temperature, and colorimetric modes were 0.04, 0.09, and 5 ng mL-1, respectively. The recoveries for detecting chlorothalonil supplemented in Astragalus and Honeysuckle with pressure mode were 84.0-110% and 108-114%, respectively. Therefore, the ICS presented a portable, sensitive, accurate, and flexible multimodal strategy suitable for point-of-care testing.


Assuntos
Colorimetria , Nanocompostos , Nitrilas , Platina , Temperatura , Nanocompostos/química , Platina/química , Imunoensaio/métodos , Nitrilas/química , Pressão , Titânio/química , Limite de Detecção
20.
Anal Chem ; 96(21): 8740-8746, 2024 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-38722256

RESUMO

Pressure and temperature, as common physical parameters, are important for monitoring human health. In contrast, single-mode monitoring is prone to causing experimental errors. Herein, we innovatively designed a dual-mode flexible sensing platform based on a platinum/zinc-meso-tetrakis(4-carboxyphenyl)porphyrin (Pt/Zn-TCPP) nanozyme for the quantitative monitoring of carcinoembryonic antigen (CEA) in biological fluids with pressure and temperature readouts. The Pt/Zn-TCPP nanozyme with catalytic and photothermal efficiencies was synthesized by means of integrating photosensitizers into porous materials. The flexible sensing system after the antigen-antibody reaction recognized the pressure using a flexible skin-like pressure sensor with a digital multimeter readout, whereas the temperature was acquired via the photoheat conversion system of the Pt/Zn-TCPP nanozyme under 808 nm near-infrared (NIR) irradiation using a portable NIR imaging camera on a smartphone. Meanwhile, the dual-mode flexible sensing system was carried out on a homemade three-dimensional (3D)-printed device. Results revealed that the developed dual-mode immunosensing platform could exhibit good pressure and temperature responses within the dynamic range of 0.5-100 ng mL-1 CEA with the detection limits of 0.24 and 0.13 ng mL-1, respectively. In addition, the pressure and temperature were sensed simultaneously without crosstalk interference. Importantly, the dual-mode flexible immunosensing system can effectively avoid false alarms during the measurement, thus providing great potential for simple and low-cost development for point-of-care testing.


Assuntos
Antígeno Carcinoembrionário , Platina , Pressão , Temperatura , Zinco , Platina/química , Imunoensaio/métodos , Zinco/química , Antígeno Carcinoembrionário/análise , Humanos , Porfirinas/química , Nanoestruturas/química , Limite de Detecção
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