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Indian Journal of Ophthalmology Mar 2023Several characteristic vascular changes can be observed in the glaucomatous eyes, including changes in the vessel configuration and caliber, presence of collateral...
BACKGROUND
Several characteristic vascular changes can be observed in the glaucomatous eyes, including changes in the vessel configuration and caliber, presence of collateral vessel on disk, and disk hemorrhage.
PURPOSE
This video describes characteristic vascular changes in the optic nerve head, which can be observed on clinical examination in the glaucomatous eyes, and useful teaching points to identify the same.
SYNOPSIS
In glaucoma, as the optic cup enlarges, the normal pattern and course of retinal vessels on the optic disk are altered and show characteristic changes. Identification of these changes provides a clue to the presence of cupping.
HIGHLIGHTS
In this video, the vascular changes and its identification in the glaucomatous disc are described, which would be useful to the residents.
VIDEO LINK
https://youtu.be/2eINumBx33E.
Topics: Humans; Glaucoma; Optic Disk; Physical Examination; Retinal Vessels
PubMed: 36872755
DOI: 10.4103/ijo.IJO_2621_22 -
Developmental Biology Aug 2021The basic structure of the eye, which is crucial for visual function, is established during the embryonic process of optic cup morphogenesis. Molecular pathways of... (Review)
Review
The basic structure of the eye, which is crucial for visual function, is established during the embryonic process of optic cup morphogenesis. Molecular pathways of specification and patterning are integrated with spatially distinct cell and tissue shape changes to generate the eye, with discrete domains and structural features: retina and retinal pigment epithelium enwrap the lens, and the optic fissure occupies the ventral surface of the eye and optic stalk. Interest in the underlying cell biology of eye morphogenesis has led to a growing body of work, combining molecular genetics and imaging to quantify cellular processes such as adhesion and actomyosin activity. These studies reveal that intrinsic machinery and spatiotemporally specific extrinsic inputs collaborate to control dynamics of cell movements and morphologies. Here we consider recent advances in our understanding of eye morphogenesis, with a focus on the mechanics of eye formation throughout vertebrate systems, including insights and potential opportunities using organoids, which may provide a tractable system to test hypotheses from embryonic models.
Topics: Actomyosin; Animals; Cell Movement; Eye; Humans; Lens, Crystalline; Morphogenesis; Optic Disk; Organogenesis; Retina; Retinal Pigment Epithelium; Signal Transduction; Vertebrates
PubMed: 33811855
DOI: 10.1016/j.ydbio.2021.03.023 -
Frontiers in Bioengineering and... 2020Intervertebral disk (IVD) degeneration is associated with most cases of cervical and lumbar spine pathologies, amongst which chronic low back pain has become the primary... (Review)
Review
Intervertebral disk (IVD) degeneration is associated with most cases of cervical and lumbar spine pathologies, amongst which chronic low back pain has become the primary cause for loss of quality-adjusted life years. Biomaterials science and tissue engineering have made significant progress in the replacement, repair and regeneration of IVD tissue, wherein hydrogel has been recognized as an ideal biomaterial to promote IVD regeneration in recent years. Aspects such as ease of use, mechanical properties, regenerative capacity, and their applicability as carriers for regenerative and anti-degenerative factors determine their suitability for IVD regeneration. This current review provides an overview of naturally derived and synthetic hydrogels that are related to their clinical applications for IVD regeneration. Although each type has its own unique advantages, it rarely becomes a standard product in truly clinical practice, and a more rational design is proposed for future use of biomaterials for IVD regeneration. This review aims to provide a starting point and inspiration for future research work on development of novel biomaterials and biotechnology.
PubMed: 32714917
DOI: 10.3389/fbioe.2020.00745 -
Journal of Microscopy Nov 2022Adaptive optics is being applied widely to a range of microscopies in order to improve imaging quality in the presence of specimen-induced aberrations. We present here...
Adaptive optics is being applied widely to a range of microscopies in order to improve imaging quality in the presence of specimen-induced aberrations. We present here the first implementation of wavefront-sensorless adaptive optics for a laser-free, aperture correlation, spinning disk microscope. This widefield method provides confocal-like optical sectioning through use of a patterned disk in the illumination and detection paths. Like other high-resolution microscopes, its operation is compromised by aberrations due to refractive index mismatch and variations within the specimen. Correction of such aberrations shows improved signal level, contrast and resolution.
Topics: Optics and Photonics; Microscopy; Refractometry; Lasers
PubMed: 33128278
DOI: 10.1111/jmi.12976 -
Science Progress Oct 2021Disk springs are widely used as preload and isolation due to their unique mechanical properties. In the prior research, the effect of linear friction on the disk spring...
Disk springs are widely used as preload and isolation due to their unique mechanical properties. In the prior research, the effect of linear friction on the disk spring was considered, but contact stiffness, another nonlinear contact factor, is ignored. Accordingly, in this paper, the asymmetric displacements of the contact edges are first derived, and the accurate friction dissipations are obtained, as a way to evaluate the effect of friction on the system. Then the velocity of the edges was obtained to establish a dynamic friction model. Meanwhile, the contact displacement and contact stiffness of the edge are obtained by fractal contact theory. Then the nonlinear static and dynamic models of disk spring with friction and contact stiffness are established by the energy method. The load-deflection relationship, stiffness, and hysteresis of disk spring are studied with different contact states. The results show that the model considering contact stiffness and asymmetric friction dissipation can effectively evaluate the static properties of the disk spring. Friction reinforces the nonlinear behavior of the system, while contact stiffness weakens the nonlinearity of the system. And due to the influence of nonlinear contact factors, the transmissibility curves produce multiple resonance peaks.
PubMed: 34704873
DOI: 10.1177/00368504211052360 -
Current Eye Research May 2023The optic nerve mechanically loads the eye during ocular rotation, thus altering the configuration of the disk and peripapillary tissues. We used optical coherence...
PURPOSE
The optic nerve mechanically loads the eye during ocular rotation, thus altering the configuration of the disk and peripapillary tissues. We used optical coherence tomography (OCT) angiography (OCTA) to investigate mechanical strains and volume changes in disk and peripapillary blood vessels during horizontal duction.
METHODS
Structural OCT and OCTA were performed centered on optic disks; imaging was repeated in central gaze, and in 30° ab- and adduction. By an algorithm employing point-set registration of 3 D features, we developed a novel approach for measuring disk strains, and strains and volumes of the blood vessels associated with horizontal duction. Repeatability was demonstrated in each gaze position.
RESULTS
19 eyes of 10 healthy adults of average age 37 ± 15 (standard deviation, SD) years were imaged. The method was validated by demonstrating numerically consistent vascular volumes and strains for repeated imaging under identical conditions. Compared with central gaze, vascular volume increased by 5.2 ± 4.1% in adduction. Adduction and abduction caused strains of 3.0 ± 1.6% and 2.6 ± 1.8% in the optic disk, whereas blood vessels showed greater strains of 8.1 ± 1.3% and 8.2 ± 1.7%. Decomposition of strain components depending on directionality and regions demonstrated that adduction induces significant net tensile strains, suggesting traction exerted by the optic nerve. The decomposition also showed that nasotemporal compressive strains are larger in temporal hemidisks than nasal hemidisks. The Bruch's membrane opening was significantly compressed horizontally in adduction by 1.1% ( = .009).
CONCLUSION
This novel analysis combining structural OCT and OCTA demonstrates that optic disk compression during adduction is associated with disk and vascular strains much larger than reported for intraocular pressure elevation and pulsatile perfusion, as well as compressing the disk and increasing peripapillary vascular volume. These changes may be relevant to the pathogenesis of optic nerve and retinal vascular disorders.
Topics: Adult; Humans; Young Adult; Middle Aged; Optic Disk; Tomography, Optical Coherence; Optic Nerve Diseases; Optic Nerve; Angiography; Intraocular Pressure; Retinal Vessels; Fluorescein Angiography
PubMed: 36843550
DOI: 10.1080/02713683.2023.2172185 -
Global Spine Journal Jul 2021This is an experimental study using an animal model.
STUDY DESIGN
This is an experimental study using an animal model.
OBJECTIVES
Disk degeneration is a common cause of low back pain. However, few attempts have been made to proffer a medical solution. The aim of this study was to investigate the effect of aloe vera gel (AVG) on the histomorphometric changes in the intervertebral disk of annular-punctured rabbits.
METHODS
A total of 25 rabbits weighing 1.0 to 3.5 kg were used for this study; 20 rabbits were subjected to annular puncture of the L3/L4, L4/L5, and L5/L6 disks using an 18G needle. Five rabbits were randomly assigned to 5 groups (A, B, C, D, and E) of 5 animals per group. Group A was not punctured. Group B was punctured. Groups C, D, and E were punctured and given 600 400, and 200 (mg/kg) of AVG orally, respectively. The disk histology and nucleus pulposus cell count were done 6 weeks after the puncture procedure.
RESULTS
The results revealed a gradual reversal of degenerative changes in the treated groups compared with the nontreated groups ( < .05). The observed changes in the organization of the elastic and collagen content, increase in fibrochondrocyte-like cells of the nucleus pulposus and annulus fibrosus ( = .0027), and the degree of degeneration of the disk ( = .0001) in the treated groups compared with the nontreated groups were statistically significant.
CONCLUSION
Administration of AVG halted and reversed disk degeneration in an annular puncture-induced disk degeneration rabbit model.
PubMed: 32677517
DOI: 10.1177/2192568220927712 -
Journal of Bodywork and Movement... Jul 2022To investigate the effect of disk training and tape application on diminished proprioception after Lateral Ankle Sprain (LAS) in active populations. (Review)
Review
OBJECTIVE
To investigate the effect of disk training and tape application on diminished proprioception after Lateral Ankle Sprain (LAS) in active populations.
ELIGIBILITY CRITERIA
Only clinical trials investigating the effectiveness of disk training and ankle tape on proprioception deficits following LAS by assessing JPS or kinaesthesia were included.
INFORMATION SOURCES
Electronic databases of PubMed, MEDLINE, SPORTDiscus, CINAHL, Web of Science, Cochrane and PEDro were searched. The main search was conducted in February 2022.
RISK OF BIAS
The physiotherapy Evidence Database (PEDro) scale was utilised to assess the methodological quality of each article.
RESULT
The search yielded six studies investigating the effects of disk training and four studies investigating the effects of inelastic tape. Five articles showed a significant improvement on JPS after disk training. However, no difference across different intervention groups was observed in one study. Only one trial presented an immediate significant improvement when taped, while another study showed that external ankle supports significantly improved JPS after 2 weeks and after 2 months. Three of four studies found no immediate improvement on proprioceptive deficits by the use of tape.
CONCLUSIONS
This review found that disk training may improve impaired proprioception after LAS, whilst the efficacy of inelastic tape was not evident due to methodological quality of the few available studies. Further studies are needed to establish whether these interventions can be used clinically with sufficient evidence.
Topics: Ankle; Ankle Injuries; Ankle Joint; Humans; Physical Therapy Modalities; Proprioception
PubMed: 35710223
DOI: 10.1016/j.jbmt.2022.04.001 -
Microbiology Spectrum Dec 2023Carbapenem-resistant is a major global health concern due to its high prevalence and limited treatment options. Cefiderocol is the only novel Food and Drug...
Carbapenem-resistant is a major global health concern due to its high prevalence and limited treatment options. Cefiderocol is the only novel Food and Drug Administration (FDA)-approved β-lactam agent for the salvage treatment of carbapenem-resistant infection. Currently, a commercial automated susceptibility testing panel of cefiderocol is unavailable. Both the preparation of iron-depleted cation-adjusted Mueller-Hinton broth and the performance of broth microdilution are cumbersome in routine microbiology laboratories. A disk diffusion method is convenient for cefiderocol antimicrobial susceptibility testing, but limited data are available specifically for clinical isolates. Moreover, the Clinical and Laboratory Standards Institute published revisions to the cefiderocol disk diffusion breakpoints in 2022. Hence, we evaluated the performance of cefiderocol disk diffusion compared with the reference BMD against clinical isolates, especially those with cefiderocol zone diameters ≤ 14 mm.
Topics: Cefiderocol; Anti-Bacterial Agents; Acinetobacter baumannii; Carbapenems; Microbial Sensitivity Tests
PubMed: 37855593
DOI: 10.1128/spectrum.05355-22 -
Applied and Environmental Microbiology Mar 2022Bacillus cereus group isolates ( = 85) were screened for phenotypic resistance to 18 antibiotics using broth microdilution and CLSI M45 spp. breakpoints. The...
Comparative Analysis of Bacillus cereus Group Isolates' Resistance Using Disk Diffusion and Broth Microdilution and the Correlation between Antimicrobial Resistance Phenotypes and Genotypes.
Bacillus cereus group isolates ( = 85) were screened for phenotypic resistance to 18 antibiotics using broth microdilution and CLSI M45 spp. breakpoints. The susceptibility to 9 out of 18 antibiotics was also tested using disk diffusion method and M100 Staphylococcus spp. breakpoints when available. Overall, a high prevalence of susceptibility to clinically relevant antibiotics was identified using broth microdilution. For most tested antibiotics, a poor correlation was found between zones of inhibition and MICs. Using the broth microdilution results as a reference for comparison, we identified high error rates and low categorical agreement between results produced using disk diffusion and broth microdilution for the seven tested antibiotics with defined breakpoints. This suggests that disk diffusion should be avoided for AST of B. cereus group isolates. Further, we detected antimicrobial resistance genes with ARIBA and ABRIcate to calculate the sensitivity and specificity for predicting phenotypic resistance determined using broth microdilution based on the presence of detected antimicrobial resistance genes (ARGs). ARGs with poor sensitivity and high specificity included (rifampicin, 0%, 93%), (erythromycin, 0%, 99%), (penicillin, 29%, 100%), and (penicillin, 56%, 100%). Compared to penicillin, and had lower specificity for the prediction of ampicillin resistance. Overall, none of the ARGs had both high sensitivity and specificity, suggesting the need for further study of the mechanisms underlying phenotypic antimicrobial resistance in the B. cereus group. Bacillus cereus group includes human pathogens that can cause severe infections requiring antibiotic treatment. Screening of environmental and food isolates for antimicrobial resistance can provide insight into what antibiotics may be more effective therapeutic options based on the lower prevalence of resistance. Currently, the comparison of antimicrobial susceptibility testing results using the disk diffusion method is complicated by the fact that many previous studies have used Staphylococcus spp. breakpoints to interpret their results. In this study, we compared the results of disk diffusion interpreted using the Staphylococcus spp. breakpoints against the results of broth microdilution interpreted using spp. breakpoints. We demonstrated that the disk diffusion method does not produce reliable results for B. cereus group isolates and should therefore be avoided. This study also provides new insight into poor associations between the presence of antimicrobial resistance genes and resistance phenotypes for the B. cereus group.
Topics: Anti-Bacterial Agents; Anti-Infective Agents; Bacillus; Bacillus cereus; Drug Resistance, Bacterial; Genotype; Microbial Sensitivity Tests; Phenotype
PubMed: 35225691
DOI: 10.1128/aem.02302-21