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Annals of Intensive Care Feb 2022A sequential change in body position from supine-to-both lateral positions under constant ventilatory settings could be used as a postural recruitment maneuver in case...
BACKGROUND
A sequential change in body position from supine-to-both lateral positions under constant ventilatory settings could be used as a postural recruitment maneuver in case of acute respiratory distress syndrome (ARDS), provided that sufficient positive end-expiratory pressure (PEEP) prevents derecruitment. This study aims to evaluate the feasibility and physiological effects of a sequential postural recruitment maneuver in early mechanically ventilated COVID-19 ARDS patients.
METHODS
A cohort of 15 patients receiving lung-protective mechanical ventilation in volume-controlled with PEEP based on recruitability were prospectively enrolled and evaluated in five sequentially applied positions for 30 min each: Supine-baseline; Lateral-1st side; 2nd Supine; Lateral-2nd side; Supine-final. PEEP level was selected using the recruitment-to-inflation ratio (R/I ratio) based on which patients received PEEP 12 cmHO for R/I ratio ≤ 0.5 or PEEP 15 cmHO for R/I ratio > 0.5. At the end of each period, we measured respiratory mechanics, arterial blood gases, lung ultrasound aeration, end-expiratory lung impedance (EELI), and regional distribution of ventilation and perfusion using electric impedance tomography (EIT).
RESULTS
Comparing supine baseline and final, respiratory compliance (29 ± 9 vs 32 ± 8 mL/cmHO; p < 0.01) and PaO/FIO ratio (138 ± 36 vs 164 ± 46 mmHg; p < 0.01) increased, while driving pressure (13 ± 2 vs 11 ± 2 cmHO; p < 0.01) and lung ultrasound consolidation score decreased [5 (4-5) vs 2 (1-4); p < 0.01]. EELI decreased ventrally (218 ± 205 mL; p < 0.01) and increased dorsally (192 ± 475 mL; p = 0.02), while regional compliance increased in both ventral (11.5 ± 0.7 vs 12.9 ± 0.8 mL/cmHO; p < 0.01) and dorsal regions (17.1 ± 1.8 vs 18.8 ± 1.8 mL/cmHO; p < 0.01). Dorsal distribution of perfusion increased (64.8 ± 7.3% vs 66.3 ± 7.2%; p = 0.01).
CONCLUSIONS
Without increasing airway pressure, a sequential postural recruitment maneuver improves global and regional respiratory mechanics and gas exchange along with a redistribution of EELI from ventral to dorsal lung areas and less consolidation. Trial registration ClinicalTrials.gov, NCT04475068. Registered 17 July 2020, https://clinicaltrials.gov/ct2/show/NCT04475068.
PubMed: 35150355
DOI: 10.1186/s13613-022-00988-9 -
PloS One 2021The purpose of this study was to biomechanically compare the stability of first metatarsophalangeal (MTP1) joint arthrodesis with dorsally and medially positioned plates.
OBJECTIVE
The purpose of this study was to biomechanically compare the stability of first metatarsophalangeal (MTP1) joint arthrodesis with dorsally and medially positioned plates.
METHODS
A physical model of the MTP1 joint consists of printed synthetic bones, a titanium locking plate and screws. In the experiments, samples with dorsally and medially positioned plates were subjected to loading of ground load character in a universal testing machine. Force-displacement relations and relative displacements of bones were recorded. The obtained results were used to validate the corresponding finite element models of the MTP1 joint. Nonlinear finite element simulations of the toe-off phase of gait were performed to determine the deformation and stress state in the MTP1 joint for two positions of the plate.
RESULTS
In numerical simulations, the maximum displacement in the dorsal direction was noticed at the tip of the distal phalanx and was equal to 19.6 mm for the dorsal plate and 9.63 mm for the medial plate for a resultant force of 150 N. Lower relative bone displacements and smaller plastic deformation in the plate were observed in the model with the medial plate. Stress values were also smaller in the medially positioned plate and locking screws compared to fixation with the dorsal plate.
CONCLUSIONS
A medially positioned locking plate provides better stability of the MTP1 joint than a dorsally positioned plate due to greater vertical bending stiffness of the medial plate. Smaller relative bone displacements observed in fixation with the medial plate may be beneficial for the bone healing process. Moreover, lower stress values may decrease the risk of complications associated with hardware failure.
Topics: Arthrodesis; Biomechanical Phenomena; Bone Plates; Bone and Bones; Finite Element Analysis; Humans; Metatarsophalangeal Joint; Models, Anatomic; Stress, Mechanical
PubMed: 34852005
DOI: 10.1371/journal.pone.0260572 -
Fluids and Barriers of the CNS Jan 2023Detecting changes in pulsatile cerebrospinal fluid (CSF) flow may assist clinical management decisions, but spinal CSF flow is relatively understudied. Traumatic spinal...
BACKGROUND
Detecting changes in pulsatile cerebrospinal fluid (CSF) flow may assist clinical management decisions, but spinal CSF flow is relatively understudied. Traumatic spinal cord injuries (SCI) often cause spinal cord swelling and subarachnoid space (SAS) obstruction, potentially causing pulsatile CSF flow changes. Pigs are emerging as a favoured large animal SCI model; therefore, the aim of this study was to characterise CSF flow along the healthy pig spine.
METHODS
Phase-contrast magnetic resonance images (PC-MRI), retrospectively cardiac gated, were acquired for fourteen laterally recumbent, anaesthetised and ventilated, female domestic pigs (22-29 kg). Axial images were obtained at C2/C3, T8/T9, T11/T12 and L1/L2. Dorsal and ventral SAS regions of interest (ROI) were manually segmented. CSF flow and velocity were determined throughout a cardiac cycle. Linear mixed-effects models, with post-hoc comparisons, were used to identify differences in peak systolic/diastolic flow, and maximum velocity (cranial/caudal), across spinal levels and dorsal/ventral SAS. Velocity wave speed from C2/C3 to L1/L2 was calculated.
RESULTS
PC-MRI data were obtained for 11/14 animals. Pulsatile CSF flow was observed at all spinal levels. Peak systolic flow was greater at C2/C3 (dorsal: - 0.32 ± 0.14 mL/s, ventral: - 0.15 ± 0.13 mL/s) than T8/T9 dorsally (- 0.04 ± 0.03 mL/s; p < 0.001), but not different ventrally (- 0.08 ± 0.08 mL/s; p = 0.275), and no difference between thoracolumbar levels (p > 0.05). Peak diastolic flow was greater at C2/C3 (0.29 ± 0.08 mL/s) compared to T8/T9 (0.03 ± 0.03 mL/s, p < 0.001) dorsally, but not different ventrally (p = 1.000). Cranial and caudal maximum velocity at C2/C3 were greater than thoracolumbar levels dorsally (p < 0.001), and T8/T9 and L1/L2 ventrally (p = 0.022). Diastolic velocity wave speed was 1.41 ± 0.39 m/s dorsally and 1.22 ± 0.21 m/s ventrally, and systolic velocity wave speed was 1.02 ± 0.25 m/s dorsally and 0.91 ± 0.22 m/s ventrally.
CONCLUSIONS
In anaesthetised and ventilated domestic pigs, spinal CSF has lower pulsatile flow and slower velocity wave propagation, compared to humans. This study provides baseline CSF flow at spinal levels relevant for future SCI research in this animal model.
Topics: Humans; Female; Swine; Animals; Retrospective Studies; Magnetic Resonance Imaging; Cerebrospinal Fluid Pressure; Spinal Cord; Sus scrofa; Cerebrospinal Fluid
PubMed: 36653870
DOI: 10.1186/s12987-022-00401-4 -
Frontiers in Neural Circuits 2023The cochlear nucleus (CN) is often regarded as the gateway to the central auditory system because it initiates all ascending pathways. The CN consists of dorsal and...
The cochlear nucleus (CN) is often regarded as the gateway to the central auditory system because it initiates all ascending pathways. The CN consists of dorsal and ventral divisions (DCN and VCN, respectively), and whereas the DCN functions in the analysis of spectral cues, circuitry in VCN is part of the pathway focused on processing binaural information necessary for sound localization in horizontal plane. Both structures project to the inferior colliculus (IC), which serves as a hub for the auditory system because pathways ascending to the forebrain and descending from the cerebral cortex converge there to integrate auditory, motor, and other sensory information. DCN and VCN terminations in the IC are thought to overlap but given the differences in VCN and DCN architecture, neuronal properties, and functions in behavior, we aimed to investigate the pattern of CN connections in the IC in more detail. This study used electrophysiological recordings to establish the frequency sensitivity at the site of the anterograde dye injection for the VCN and DCN of the CBA/CaH mouse. We examined their contralateral projections that terminate in the IC. The VCN projections form a topographic sheet in the central nucleus (CNIC). The DCN projections form a tripartite set of laminar sheets; the lamina in the CNIC extends into the dorsal cortex (DC), whereas the sheets to the lateral cortex (LC) and ventrolateral cortex (VLC) are obliquely angled away. These fields in the IC are topographic with low frequencies situated dorsally and progressively higher frequencies lying more ventrally and/or laterally; the laminae nestle into the underlying higher frequency fields. The DCN projections are complementary to the somatosensory modules of layer II of the LC but both auditory and spinal trigeminal terminations converge in the VLC. While there remains much to be learned about these circuits, these new data on auditory circuits can be considered in the context of multimodal networks that facilitate auditory stream segregation, signal processing, and species survival.
Topics: Mice; Animals; Inferior Colliculi; Cochlear Nucleus; Auditory Pathways; Mice, Inbred CBA; Neurons
PubMed: 37554670
DOI: 10.3389/fncir.2023.1229746 -
International Journal of Molecular... Dec 2022and are recognized as members of the genus because of their dorsally compressed mericarps with slightly prominent dorsal ribs and narrowly winged lateral ribs....
and are recognized as members of the genus because of their dorsally compressed mericarps with slightly prominent dorsal ribs and narrowly winged lateral ribs. However, these species are not similar to other taxa but resemble in overall morphology. To check the taxonomic positions of and , we sequenced their complete plastid genome (plastome) sequences and, together with eleven previously published plastomes, performed comprehensively comparative analyses. The thirteen plastomes were highly conserved and similar in structure, size, GC content, gene content and order, IR borders, and the patterns of codon bias, RNA editing, and simple sequence repeats (SSRs). Nevertheless, twelve mutation hotspots (K, C, 15, 8, 2, A-D, N-M, A-K, 2-C2, 4-T, H-A, and 2-L) were selected. Moreover, both the phylogenetic analyses based on plastomes and on nuclear ribosomal DNA internal transcribed spacer (ITS) sequences robustly supported that and nested in , and this was further confirmed by the morphological evidence. Hence, transferring and into genus is reasonable and convincing, and two new combinations are presented.
Topics: Apiaceae; Magnoliopsida; Phylogeny; Genome, Plastid; Plastids
PubMed: 36613825
DOI: 10.3390/ijms24010382 -
International Journal of Environmental... Feb 2023The choroid, a multifunctional tissue, has been the focus of research interest for many scientists. Its morphology and morphometry facilitate an understanding of...
The choroid, a multifunctional tissue, has been the focus of research interest for many scientists. Its morphology and morphometry facilitate an understanding of pathological processes within both the choroid and retina. This study aimed to determine the choroidal layer thicknesses in healthy, mixed-breed mesocephalic dogs, both male (M) and female (F), using spectral domain optical coherence tomography (SD-OCT) with radial, cross-sectional, and linear scans. The dogs were divided into two groups based on age: middle-aged (MA) and senior (SN). Thicknesses of choroidal layers, namely RPE-Bruch's membrane-choriocapillaris complex (RPE-BmCc) with tapetum lucidum in the tapetal fundus, the medium-sized vessel layer (MSVL), and the large vessel layer with lamina suprachoroidea (LVLS), as well as whole choroidal thickness (WCT), were measured manually using the caliper function integrated into the OCT software. Measurement was performed dorsally and ventrally at a distance of 5000-6000 μm temporally and nasally at a distance of 4000-7000 μm to the optic disc on enhanced depth scans. The measurements were conducted temporally and nasally in both the tapetal (temporal tapetal: TempT, nasal tapetal: NasT) and nontapetal (temporal nontapetal: TempNT, nasal nontapetal: NasNT) fundus. The ratio of the MSVL thickness to the LVLS thickness for each region was calculated. In all examined dogs, the RPE-BmCc in the dorsal (D) region and MSVL in the Tt region were significantly thicker than those in the other regions. The MSVL was thinner in the ventral (V) region than in the D, TempT, TempNT and NasT regions. The MSVL was significantly thinner in the NasNT region than in the D region. LVLS thickness and WCT were significantly greater in the D and TempT regions than those in the other regions and significantly lesser in the V region than those in the other regions. The MSVL-to-LVLS thickness ratio did not differ between the age groups. Our results reveal that the choroidal thickness profile does not depend on age. Our findings can be used to document the emergence and development of various choroidal diseases in dogs in the future.
Topics: Male; Dogs; Animals; Female; Tomography, Optical Coherence; Cross-Sectional Studies; Choroid; Retina; Fundus Oculi
PubMed: 36833819
DOI: 10.3390/ijerph20043121 -
Proceedings. Biological Sciences Aug 2021Tetrapods use their neck to move the head three-dimensionally, relative to the body and limbs. Fish lack this anatomical neck, yet during feeding many species elevate...
Tetrapods use their neck to move the head three-dimensionally, relative to the body and limbs. Fish lack this anatomical neck, yet during feeding many species elevate (dorsally rotate) the head relative to the body. Cranial elevation is hypothesized to result from the craniovertebral and cranial-most intervertebral joints acting as a neck, by dorsally rotating (extending). However, this has never been tested due to the difficulty of visualizing and measuring vertebral motion . I used X-ray reconstruction of moving morphology to measure three-dimensional vertebral kinematics in rainbow trout () and Commerson's frogfish () during feeding. Despite dramatically different morphologies, in both species dorsoventral rotations extended far beyond the craniovertebral and cranial intervertebral joints. Trout combine small (most less than 3°) dorsal rotations over up to a third of their intervertebral joints to elevate the neurocranium. Frogfish use extremely large (often 20-30°) rotations of the craniovertebral and first intervertebral joint, but smaller rotations occurred across two-thirds of the vertebral column during cranial elevation. Unlike tetrapods, fish rotate large regions of the vertebral column to rotate the head. This suggests both cranial and more caudal vertebrae should be considered to understand how non-tetrapods control motion at the head-body interface.
Topics: Animals; Biomechanical Phenomena; Cervical Vertebrae; Joints; Motion; Radiography
PubMed: 34428973
DOI: 10.1098/rspb.2021.1091 -
Journal of Evolutionary Biology Nov 2022Many organisms use conspicuous colour patterns to advertise their toxicity or unpalatability, a strategy known as aposematism. Despite the recognized benefits of this...
Many organisms use conspicuous colour patterns to advertise their toxicity or unpalatability, a strategy known as aposematism. Despite the recognized benefits of this anti-predator tactic, not all chemically defended species exhibit warning coloration. Here, we use a comparative approach to investigate which factors predict the evolution of conspicuousness in frogs, a group in which conspicuous coloration and toxicity have evolved multiple times. We extracted colour information from dorsal and ventral photos of 594 frog species for which chemical defence information was available. Our results show that chemically defended and diurnal species have higher internal chromatic contrast, both ventrally and dorsally, than chemically undefended and/or nocturnal species. Among species that are chemically defended, conspicuous coloration is more likely to occur if species are diurnal. Our results also suggest that the evolution of conspicuous colour is more likely to occur in chemically defended prey with smaller body size. We discuss potential explanations for this association and suggest that prey profitability (related to body size) could be an important force driving the macroevolution of warning signals.
Topics: Animals; Biological Evolution; Anura; Biological Mimicry
PubMed: 36129907
DOI: 10.1111/jeb.14092 -
Cureus Mar 2023Zenker's diverticulum (ZD) is a type of esophageal diverticulum, a relatively rare disease in the pharyngoesophageal area. It is a pulsion diverticulum, or false...
Zenker's diverticulum (ZD) is a type of esophageal diverticulum, a relatively rare disease in the pharyngoesophageal area. It is a pulsion diverticulum, or false diverticulum, located dorsally at the wall between the pharynx and esophagus. This area is known as Killian's triangle or dehiscence and is a region of relative weakness. Common symptoms of ZD include dysphagia, choking, persistent cough, loss of weight, hoarseness, halitosis, regurgitation of undigested food, and borborygmi within the cervical region. We are reporting a case of oropharyngeal dysphagia due to a ZD in a 65-year-old man with a history of worsening dysphagia for two years. Clinical presentation, diagnosis, and treatment options for ZD are discussed, along with the underlying pathophysiology of this condition.
PubMed: 37123671
DOI: 10.7759/cureus.36783