-
Journal of Cell Science Jan 2019Epithelial tissues function as barriers that separate the organism from the environment. They usually have highly curved shapes, such as tubules or cysts. However, the...
Epithelial tissues function as barriers that separate the organism from the environment. They usually have highly curved shapes, such as tubules or cysts. However, the processes by which the geometry of the environment and the cell's mechanical properties set the epithelium shape are not yet known. In this study, we encapsulated two epithelial cell lines, MDCK and J3B1A, into hollow alginate tubes and grew them under cylindrical confinement forming a complete monolayer. MDCK monolayers detached from the alginate shell at a constant rate, whereas J3B1A monolayers detached at a low rate unless the tube radius was reduced. We showed that this detachment is driven by contractile stresses in the epithelium and can be enhanced by local curvature. This allows us to conclude that J3B1A cells exhibit smaller contractility than MDCK cells. Monolayers inside curved tubes detach at a higher rate on the outside of a curve, confirming that detachment is driven by contraction.
Topics: Alginates; Animals; Biomechanical Phenomena; Cell Adhesion; Cell Culture Techniques; Cell Line; Cell Movement; Cells, Immobilized; Collagen; Dogs; Drug Combinations; Epithelial Cells; Laminin; Madin Darby Canine Kidney Cells; Mechanotransduction, Cellular; Mice; Organ Specificity; Proteoglycans
PubMed: 30578312
DOI: 10.1242/jcs.222372 -
Retina (Philadelphia, Pa.) Dec 2023To describe the surgical technique using the guarded-needle external drainage for a wide variety of applications in vitreoretinal surgery. (Review)
Review
PURPOSE
To describe the surgical technique using the guarded-needle external drainage for a wide variety of applications in vitreoretinal surgery.
METHODS
A step-by-step procedure and a surgical video using the guarded-needle external drainage technique are presented. In addition, a series of representative cases with wide-ranging diagnoses who underwent the technique is reviewed.
DESCRIPTION AND TECHNIQUE
The guarded-needle using a 27-gauge thin-walled TSK needle (TSK Laboratory International) and a trimmed 70 buckle sleeve are connected to the active extrusion tubing of the vitrectomy machine. External drainage is performed by actively aspirating subretinal fluid using low active vacuum. The guarded-needle external drainage technique is used in cases with bullous detachments, and small and anterior breaks, when performing scleral buckle, for prevention of underfill when using oil tamponade in cases with choroidal effusion, addressing subretinal gas/air, lysing a subretinal band, draining a suprachoroidal hemorrhage, for diabetic tractional retinal detachments, detachments with no definitive break, and subretinal biopsy in exudative detachments.
CONCLUSION
The guarded-needle external drainage has a wide range of applications in vitreoretinal surgery.
Topics: Humans; Vitreoretinal Surgery; Scleral Buckling; Drainage; Retinal Detachment; Choroid Hemorrhage; Vitrectomy
PubMed: 35604721
DOI: 10.1097/IAE.0000000000003483 -
Acta Histochemica Jan 2019The vomeronasal system (VNS) is an accessory olfactory structure present in most mammals adhibited to the detection of specific chemosignals implied in social and...
The vomeronasal system (VNS) is an accessory olfactory structure present in most mammals adhibited to the detection of specific chemosignals implied in social and reproductive behavior. The VNS comprises the vomeronasal organ (VNO), vomeronasal nerve and accessory olfactory bulb. VNO is characterized by a neuroepithelium constituted by bipolar neurons and supporting and stem/progenitor cells. In humans, VNO is present during fetal life and is supposed to possess chemoreceptor activity and participate in gonadotropin-releasing hormone neuronal precursor migration toward the hypothalamus. Instead, the existence and functions of VNO in postnatal life is debated. Vascular endothelial growth factor (VEGF) and its receptors (VEGFRs) have been demonstrated to play fundamental roles in various neurogenic events. However, there are no data regarding the localization and possible function of VEGF/VEGFRs in human fetal VNO. Therefore, this study was conceived to investigate the expression of VEGF/VEGFRs in human VNO in an early developmental period (9-12 weeks of gestation), when this organ appears well structured. Coronal sections of maxillofacial specimens were subjected to peroxidase-based immunohistochemistry for VEGF, VEGFR-1 and VEGFR-2. Double immunofluorescence for VEGF, VEGFR-1 or VEGFR-2 and the neuronal marker protein gene product 9.5 (PGP 9.5) was also performed. VEGF expression was evident in the entire VNO epithelium, with particularly strong reactivity in the middle layer. Strongly VEGF-immunostained cells with aspect similar to bipolar neurons and/or their presumable precursors were detected in the middle and basal layers. Cells detaching from the basal epithelial layer and detached cell groups in the surrounding lamina propria showed moderate/strong VEGF expression. The strongest VEGFR-1 and VEGFR-2 expression was detected in the apical epithelial layer. Cells with aspect similar to bipolar neurons and/or their presumable precursors located in the middle and basal layers and the detaching/detached cells displayed a VEGFR-1 and VEGFR-2 reactivity similar to that of VEGF. The basal epithelial layer exhibited stronger staining for VEGFRs than for VEGF. Cells with morphology and VEGF/VEGFR expression similar to those of the detaching/detached cells were also detected in the middle and basal VNO epithelial layers. Double immunofluorescence using anti-PGP 9.5 antibodies demonstrated that most of the VEGF/VEGFR-immunoreactive cells were neuronal cells. Collectively, our findings suggest that during early fetal development the VEGF/VEGFR system might be involved in the presumptive VNO chemoreceptor activity and neuronal precursor migration.
Topics: Fluorescent Antibody Technique; Humans; Immunohistochemistry; Vascular Endothelial Growth Factor A; Vascular Endothelial Growth Factor Receptor-1; Vomeronasal Organ
PubMed: 30442382
DOI: 10.1016/j.acthis.2018.11.001 -
Scientific Reports Dec 2022Adherent cell cultures are often dissociated from their culture vessel (and each other) through enzymatic harvesting, where the detachment response is monitored by an...
Adherent cell cultures are often dissociated from their culture vessel (and each other) through enzymatic harvesting, where the detachment response is monitored by an operator. However, this approach is lacking standardisation and reproducibility, and prolonged exposure or too high concentrations can affect the cell's viability and differentiation potential. Quantitative monitoring systems are required to characterise the cell detachment response and objectively determine the optimal time-point to inhibit the enzymatic reaction. State-of-the-art methodologies rely on bulky imaging systems and/or features (e.g. circularity) that lack robustness. In this study, lens-free imaging (LFI) technology was used to develop a novel cell detachment feature. Seven different donors were cultured and subsequently harvested with a (diluted) enzymatic harvesting solution after 3, 5 and 7 days of culture. Cell detachment was captured with the LFI set-up over a period of 20 min (every 20 s) and by optimising the reconstruction of the LFI intensity images, a new feature could be identified. Bright regions in the intensity image were identified as detaching cells and using image analysis, a method was developed to automatically extract this feature, defined as the percentage of detached cell regions. Next, the method was quantitatively and qualitatively validated on a diverse set of images. Average absolute error values of 1.49%, 1.34% and 1.97% were obtained for medium to high density and overconfluent cultures, respectively. The detachment response was quantified for all conditions and the optimal time for enzyme inhibition was reached when approximately 92.5% of the cells were detached. On average, inhibition times of 9.6-11.1 and 16.2-17.2 min were obtained for medium to high density and overconfluent cultures, respectively. In general, overconfluent cultures detached much slower, while their detachment rate was also decreased by the diluted harvesting solution. Moreover, several donors exhibited similar trends in cell detachment behaviour, with two clear outliers. Using the novel feature, measurements can be performed with an increased robustness, while the compact LFI design could pave the way for in situ monitoring in a variety of culture vessels, including bioreactors.
Topics: Reproducibility of Results; Cell Culture Techniques; Lens, Crystalline; Lenses; Diagnostic Imaging
PubMed: 36564377
DOI: 10.1038/s41598-022-22561-x -
Eye (London, England) Aug 2023To analyse risk factors and long-term outcomes after rebubbling and graft detachment in Descemet membrane endothelial keratoplasty (DMEK).
OBJECTIVES
To analyse risk factors and long-term outcomes after rebubbling and graft detachment in Descemet membrane endothelial keratoplasty (DMEK).
METHODS
176 consecutive DMEK grafts of 125 patients performed by 8 surgeons with a standardised technique between January 2015 and July 2022 were analysed. Main outcome measures were graft detachments, rebubbling rate, postoperative outcomes, and risk factors for graft failure and rebubbling.
RESULTS
6 (3.4%) grafts required rebubbling (>1/3 area detached). 40 (22.7%) grafts developed self-resolving partial detachments (<1/3 area detached). The mean time to rebubble was 16 ± 9.4 days. Mean BSCVAs at 5 years postoperative were 0.03 ± 0.16, 0.03 ± 0.14, and 0.15 ± 0.31 logMAR in fully attached, partially detached and rebubbled grafts (P = 0.437). 5-year graft survival were 98%, 90%, and 83% in fully attached, partially detached and rebubbled eyes (P = 0.02). There was significantly greater endothelial cell loss (ECL) in the rebubbled eyes (P = 0.018). Intraoperative trauma was a risk factor for graft failure (HR 1.81; 95% CI: 1.33-2.50; P = 0.023). An indication for surgery other than Fuchs endothelial dystrophy was a risk factor for rebubbling (HR 5.28; 95% CI: 5.11-72.4; P = 0.007).
CONCLUSION
DMEK grafts had better graft survival if there was no partial detachment or rebubbling at 5 years postop. There was significant ECL associated with rebubbling. A standardised technique reduces rebubbling and graft failure risk.
Topics: Humans; Descemet Membrane; Descemet Stripping Endothelial Keratoplasty; Retrospective Studies; Visual Acuity; Fuchs' Endothelial Dystrophy; Graft Survival; Endothelium, Corneal
PubMed: 36522529
DOI: 10.1038/s41433-022-02362-2 -
Methods in Molecular Biology (Clifton,... 2018We describe a recently reported method for directly applying a known, nanonewton-scale force to the nucleus in a living, intact cell. First, a suction seal is applied on...
We describe a recently reported method for directly applying a known, nanonewton-scale force to the nucleus in a living, intact cell. First, a suction seal is applied on the nuclear surface using a micropipette. Then, the micropipette is translated away from the nucleus. The nucleus deforms and translates with the moving micropipette and then eventually detaches from the micropipette and recovers (roughly) its original shape and position. At the point of detachment, the resisting force (from the deformed nucleus and connected cytoskeleton) balances the suction force. Because the suction force is precisely known and reproducibly applied, this method therefore allows comparisons of nuclear response across disruptions to the cytoskeleton, nucleus, or cell. This method is useful for quantifying nuclear elastic properties in its native, integrated environment.
Topics: Animals; Biological Assay; Biomechanical Phenomena; Cell Nucleus; Mice
PubMed: 30141040
DOI: 10.1007/978-1-4939-8691-0_8 -
Langmuir : the ACS Journal of Surfaces... Jul 2022Lamellar mesophases of insoluble lipids are readily solubilized by the micellar mesophases of soluble surfactants. This simple process underscores a broad array of...
Lamellar mesophases of insoluble lipids are readily solubilized by the micellar mesophases of soluble surfactants. This simple process underscores a broad array of biochemical methodologies, including purification, reconstitution, and crystallization of membrane proteins, as well as the isolation of detergent-resistant membrane fractions. Although much is now known about the thermodynamic driving forces of membrane solubilization, the kinetic pathways by which the surfactant alters vesicular mesophases are only beginning to be appreciated. Little is known about how these interactions affect the solubilization of more complex, multilamellar mesophases. Here, we investigate how a common zwitterionic detergent affects the solubilization of a smectic, multilamellar, cylindrical mesophase of lipids, called the myelin figure. Our results reveal that myelin solubilization occurs in a multistep manner, producing a well-defined sequence of morphologically distinct intermediates to complete solubilization. The kinetic processes producing these intermediates include (1) coiling, which encompasses the formation, propagation, and tightening of extended helices; (2) thinning, which reflects the unbinding of lamellae in the smectic stacks; and (3) detachment or retraction, which either dissociates the myelinic protrusion from the source lipid mass or returns the myelinic protrusion to the source lipid mass─all in transit toward complete solubilization. These occasionally overlapping steps are most pronounced in single-lipid component myelins, while compositionally graded multicomponent myelins inhibit the coiling step and detach more frequently. Taken together, the appearance of these intermediates during the solubilization of myelins suggests a complex free-energy landscape characterizing myelin solubilization populated by metastable, morphological intermediates correlated with locally minimized changes in energy dependent upon the mesophase's composition. This then predicts the accessibility of structurally distinct, kinetic intermediates─such as loose and tight coiled helices, peeled myelins, retracted tubes, and detached protrusions─before reaching the stable ground state corresponding to a dissolved suspension of mixed surfactant-lipid micelles.
Topics: Detergents; Excipients; Lipids; Micelles; Myelin Sheath; Pulmonary Surfactants; Solubility; Surface-Active Agents
PubMed: 35816731
DOI: 10.1021/acs.langmuir.2c00774 -
Clinically undetected retinal breaks causing retinal detachment: A review of options for management.Survey of Ophthalmology 2018The successful detection of retinal breaks is a critical step in rhegmatogenous retinal detachment surgery in order to prevent persistent/recurrent retinal detachments.... (Review)
Review
The successful detection of retinal breaks is a critical step in rhegmatogenous retinal detachment surgery in order to prevent persistent/recurrent retinal detachments. Not all retinal breaks causing retinal detachments are obvious. Retinal breaks may be obscured by opacities that are either anterior segment related, lens related, or posterior segment related. Rules to identify breaks based on subretinal fluid configuration are more difficult to apply in pseudophakic, aphakic, and scleral buckle encircled eyes-and in eyes with repeat detachments and those with proliferative vitreoretinopathy. Exudative detachments exhibit characteristic features and must be ruled out. A thorough clinical examination preoperatively is important even if a vitrectomy is planned. We review the incidence and causes of undetected breaks, along with preoperative/clinical issues that may hinder break detection. We review the literature with respect to investigative approaches and techniques that are available to the vitreoretinal surgeon when primary breaks remain clinically undetected during the preoperative examination. We broadly divide the surgical approaches into ones where the surgeon utilizes techniques to pursue actively a search for breaks versus adopting a purely speculative approach. Advantages and disadvantages of various techniques are appraised. Intuitively one might argue that an encircling scleral buckle combined with vitrectomy would give higher single operation success than pars plana vitrectomy alone because "undetected" retinal breaks would be addressed by a 360° plombage. We could not confirm this concept. Newer techniques, such as pars plana vitrectomy augmented with dye extrusion or endoscopic-assisted pars plana vitrectomy, show encouraging results. Technological advances such as intraoperative optical coherence tomography will also help to broaden the vitreoretinal surgeon's armamentarium. At this time, there is no gold standard in terms of the recommended approach, and this is reflected in the many options that are available for management. The surgeon must consider the benefits versus the risk of their preferred approach.
Topics: Coloring Agents; Diagnostic Techniques, Ophthalmological; Humans; Retinal Detachment; Retinal Perforations; Scleral Buckling; Tomography, Optical Coherence; Vitrectomy
PubMed: 28807798
DOI: 10.1016/j.survophthal.2017.08.002 -
Journal of the College of Physicians... May 2021Posterior scleritis is an underdiagnosed condition due to its rarity and is frequently misdiagnosed due to its varied presentation.1 Therefore, it is imperative to know...
Posterior scleritis is an underdiagnosed condition due to its rarity and is frequently misdiagnosed due to its varied presentation.1 Therefore, it is imperative to know that it can present clinically as exudative retinal detachment, proptosis, disc oedema, choroidal folds, subretinal mass, and myositis. We report a case of 48-year female who presented with gradual, progressive loss of vision in left eye. There were multiple exudative retinal detachments with choroidal folds and disc oedema. Ultrasonography (USG) B scan and contrast enhanced magnetic resonance imaging (MRI) orbit revealed the classic T-sign. With oral steroids, she improved clinically. Posterior scleritis is a painful condition, but the patient did not report any pain in or around the globe, which makes this case a unique experience. Key Words: Posterior scleritis, Exudative retinal detachment, T-sign.
Topics: Exophthalmos; Female; Humans; Magnetic Resonance Imaging; Retinal Detachment; Scleritis; Ultrasonography
PubMed: 34027877
DOI: 10.29271/jcpsp.2021.05.594 -
Science Bulletin Dec 2023After two continents collide, plate convergence and orogenesis are sustained because subducted continental lithosphere continues pulling the surface plate. It remains...
After two continents collide, plate convergence and orogenesis are sustained because subducted continental lithosphere continues pulling the surface plate. It remains controversial how, why, and when continental plate convergence and collision slow down and eventually cease. We use an unprecedented data coverage and present a regional-scale seismic tomographic image of the mantle structure beneath the Tibetan Plateau. In the mantle transition zone, we identify multiple high-velocity anomalies and interpret them as detached pieces of the Indian continental slab. Facilitated by internal heterogeneity of the continental lithosphere, piecewise slab detachments could reduce the slab pull force, resulting in the Miocene slowdown of the India-Eurasia convergence and coeval diachronous potassic volcanism in southern Tibet. We propose that slab detachment is a mechanism that eventually will lead to the end of the Indo-Eurasian continental collision and the Himalayan orogeny.
PubMed: 37919155
DOI: 10.1016/j.scib.2023.10.017