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ACS Biomaterials Science & Engineering Jul 2022Nanopillars can influence how bacterial cells attach to a surface. Herein, we investigated whether self-assembled zinc oxide (ZnO) nanopillars synthesized on glass...
Nanopillars can influence how bacterial cells attach to a surface. Herein, we investigated whether self-assembled zinc oxide (ZnO) nanopillars synthesized on glass substrates via the conventional hydrothermal route possess anti-biofouling properties either by reducing the amount of initially attached cells or promoting the detachment of cells from the surface or both. To avoid complications associated with manual intervention methods of assessing bacterial attachment on nanopillar surfaces, we implemented a microfluidic approach. In our study, we synthesized two nanopillar topographies: a low surface density of ZnO nanopillars and a high surface density of ZnO nanopillars. Next, we mounted microfluidic channels to each of these substrates. This microfluidic approach allowed us to gently flow , , or cells onto the nanopillars for initial attachment before systematically increasing the flowrate to attempt to detach remaining attached cells without introducing air-liquid interface artefacts during the assay. Generally, initial bacterial attachment was similar across all substrates. However, cells consistently detached more readily from high-surface-density nanopillars compared to low-surface-density nanopillars. Electron microscopy revealed that cells that attached to high-surface-density nanopillars rested atop the nanopillars, fully exposed to microfluidic shear, whereas many cells became trapped in the void space between neighboring low-surface-density nanopillars, shielding these cells from detachment. Our findings indicate that self-assembled ZnO nanopillars can provide anti-biofouling properties under submerged flow but only if synthesized at high surface density.
Topics: Biofouling; Microfluidics; Pseudomonas aeruginosa; Staphylococcus aureus; Zinc Oxide
PubMed: 35678761
DOI: 10.1021/acsbiomaterials.2c00233 -
Biophysical Journal Mar 2022By analyzing the distributions of focal adhesion (FA) lifetimes from different cell types, we found that a gamma distribution best matched the experimental...
By analyzing the distributions of focal adhesion (FA) lifetimes from different cell types, we found that a gamma distribution best matched the experimental distributions. In all but one case, it was a unimodal, non-symmetric gamma distribution. We used a mathematical model of cell motion to help understand the mechanics and data behind the FA lifetime distributions. The model uses a detach-rate function to determine how long an FA will persist before it detaches. The detach-rate function that produced distributions with a best-fit gamma curve that closely matched that of the data was both force and time dependent. Using the data gathered from the matching simulations, we calculated both the cell speed and mean FA lifetime and compared them. Where available, we also compared this relationship to that of the experimental data and found that the simulation reasonably matches it in most cases. In both the simulations and experimental data, the cell speed and mean FA lifetime are related, with longer mean lifetimes being indicative of slower speeds. We suspect that one of the main predictors of cell speed for migrating cells is the distribution of the FA lifetimes.
Topics: Cell Adhesion; Cell Movement; Computer Simulation; Focal Adhesions
PubMed: 35143774
DOI: 10.1016/j.bpj.2022.02.003 -
Investigative Ophthalmology & Visual... Jul 1990Nonrhegmatogenous retinal detachments were formed in the eyes of Dutch rabbits by subretinal injection of Hanks' balanced salt solution. The electroretinogram (ERG) was...
Nonrhegmatogenous retinal detachments were formed in the eyes of Dutch rabbits by subretinal injection of Hanks' balanced salt solution. The electroretinogram (ERG) was recorded locally from the acutely detached retina, and simultaneously from the surrounding attached retina (vitreal ERG [VERG]), before and after exposure to diffuse intense irradiation. Light adaptation elevated b-wave threshold for both the local ERG (LERG) and VERG by about 3 log units; thresholds for both responses recovered fully within 60-90 min after the irradiation. The normal time course of dark adaptation of the LERG suggests the occurrence of substantial rhodopsin regeneration in the rod photoreceptors of nonrhegmatogenously detached retina. These results differ from reports that visual pigment regeneration is slow in central serous chorioretinopathy, possibly because our detachments were studied within hours of formation, whereas some photoreceptor degeneration may be present in older clinical detachments.
Topics: Animals; Dark Adaptation; Electroretinography; Light; Photic Stimulation; Photoreceptor Cells; Rabbits; Retinal Detachment; Rhodopsin
PubMed: 2365558
DOI: No ID Found -
The Journal of Applied Psychology Dec 2022On a weekly basis, job seekers need to exert effort to successfully navigate their search. Yet, despite the notion that job seeking is likely depleting, there has been...
On a weekly basis, job seekers need to exert effort to successfully navigate their search. Yet, despite the notion that job seeking is likely depleting, there has been little research and discussion to date surrounding whether taking time to recover from job seeking can be restorative and helpful for job seekers. Applying theory from the effort-recovery model (Meijman & Mulder, 1998) and the stressor-detachment model (Sonnentag & Fritz, 2015) to the job search context, we highlight the self-regulatory and job search-related benefits associated with psychologically detaching from the job search each week. Specifically, we theorize that weekly psychological detachment from the job search (at ) helps job seekers feel recovered (at t) and, in turn, more vigorous (at + 1), prompting subsequent job search effort (at + 1); further, weekly job search effort is expected to engender an increase in subsequent interviews (at + 2). We also explore the cross-level moderating effect of implicit theories of depletion, considering whether the beneficial impact of weekly psychological detachment is contingent on how depleting job seekers perceive the search process to be. We tested our model with two weekly experience sampling studies of over 200 new labor market entrants. Across both studies, we found considerable support for our model, suggesting that taking time to psychologically detach from the job search can help job seekers maintain their well-being and obtain job search success. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Topics: Humans; Job Application
PubMed: 35084899
DOI: 10.1037/apl0000967 -
Ophthalmologica. Journal International... 1983The author studied by fluorescein angiography the vascular conditions in 50 cases of rhegmatogenous detachment. Capillary dilatation and hyperpermeability were observed...
The author studied by fluorescein angiography the vascular conditions in 50 cases of rhegmatogenous detachment. Capillary dilatation and hyperpermeability were observed on the detached retina and can be considered as an autoregulation phenomenon secondary to tissular hypoxia. Diffuse peripheral vascular occlusions were a typical finding in detachments with peripheral holes. In these cases a preexisting retinal perfusion defect was probably exaggerated by the increased resistances secondary to the detachment.
Topics: Fluorescein Angiography; Humans; Retinal Detachment; Retinal Vessels
PubMed: 6823410
DOI: 10.1159/000309255 -
The Journal of Urology Nov 1989A prostatic detaching blade for a new endoscopic method has been devised for transurethral resection of the prostate along the cleavage plane at the surgical capsule....
A prostatic detaching blade for a new endoscopic method has been devised for transurethral resection of the prostate along the cleavage plane at the surgical capsule. After partial resection of the adenoma with the loop the remaining adenoma, except for a portion at the bladder neck, is detached from the surgical capsule under direct vision with the detaching blade. The remaining adenoma then is removed by the electric loop down to the detached surgical capsule. This method of resection has been performed in 200 patients with improvement of symptoms in all. Detachment of the adenoma along the surgical capsule always is possible, thereby defining the depth of resection and minimizing the risk of capsular perforation compared to standard transurethral prostatectomy.
Topics: Aged; Aged, 80 and over; Humans; Male; Middle Aged; Postoperative Complications; Prostatectomy; Prostatic Hyperplasia
PubMed: 2478727
DOI: 10.1016/s0022-5347(17)39047-x -
Ophthalmology Dec 2002To report the causes of retinal detachment in an African setting and the outcome after surgery.
PURPOSE
To report the causes of retinal detachment in an African setting and the outcome after surgery.
DESIGN
Noncomparative interventional case series.
PARTICIPANTS
A total of 361 eyes in 345 patients.
METHODS
Data were collected from patients' case notes. A minimum of 2 months' follow-up was available for 254 eyes. Risk factors for poor anatomic or visual outcome were analyzed by logistic regression.
MAIN OUTCOME MEASURES
Primary anatomic success, which was defined as an attached retina at least 2 months after the initial surgery, without any additional interventions; final anatomic success, defined as an attached retina at least 2 months after the latest intervention; and visual outcome, defined as the corrected visual acuity at least 2 months after the last operation.
RESULTS
The macula was detached at presentation in 332 (91.9%) eyes. In 203 (56.2%) eyes, the retina had been detached for >1 month. Proliferative vitreoretinopathy (PVR)-grade C1 or worse-was present in 63 (17.5%) eyes. Thirty eyes (8.3%) had giant retinal tears. Ninety-five patients (27.5%) were blind (<20/400 in the better eye) at presentation. The retina was successfully reattached with 1 operation in 186 (73.2%) eyes. The most frequent cause of primary failure was missed breaks or new breaks. The final anatomic success rate in eyes observed for at least 8 weeks after the last operation was 88.2%. Giant retinal tear and PVR were significant independent predictors of anatomic failure. In eyes with successfully reattached retinas, 63.9% achieved 20/200 vision or better. Among successfully reattached macula-off detachments, risk factors for a poor visual outcome (<20/200) were macular hole, duration of retinal detachment >1 month, and poor preoperative acuity. Of 74 blind patients with 2 months' follow-up, only 23 (31.1%) remained blind at the latest follow-up.
CONCLUSIONS
Retinal detachment is a treatable cause of blindness in Africa. Despite late presentation and complex pathology, surgical repair is frequently successful and often restores navigational vision. Greater emphasis should be given to the recognition and treatment of retinal detachment in regional training programs for ophthalmologists and primary eye care workers.
Topics: Female; Humans; Kenya; Male; Medical Audit; Middle Aged; Retinal Detachment; Retrospective Studies; Risk Factors; Visual Acuity; Vitrectomy
PubMed: 12466171
DOI: 10.1016/s0161-6420(02)01284-8 -
Frontiers in Immunology 2022The nature of the culture dish surface and the technique used to detach adherent cells could very likely influence the cell viability and cell membrane protein integrity...
The nature of the culture dish surface and the technique used to detach adherent cells could very likely influence the cell viability and cell membrane protein integrity of harvested macrophages. Several previous studies assessed the detachment efficacies of enzymatic and non-enzymatic methods for harvesting the single cell suspensions of macrophages, but a comprehensive study assessing different dissociation methods and culture conditions for detaching functionally different macrophage populations has not yet been reported. In this study, the well-established GM-CSF and M-CSF differentiated bone marrow derived macrophage models (GM-BMDMs and M-BMDMs), we compared four commonly used enzymatic (trypsin and accutase) and non-enzymatic (PBS and EDTA) dissociation methods along with necessary mechanical detaching steps (scraping and pipetting) to evaluate the viable cell recovery and cell surface marker integrality of GM-BMDMs and M-BMDMs cultured on standard cell culture dish (TC dish), or on culture dish (noTC dish) that was not conditioned to enhance adherence. The data showed that accutase yielded a better recovery of viable cells comparing with PBS and EDTA, especially for tightly adherent GM-BMDMs on TC dishes, with a relatively higher level of detected cell membrane marker F4/80 than trypsin. An additional gradient centrifugation-based dead cell removal approach could increase the proportion of viable cells for TC cultured GM-BMDMs after accutase dissociation. Furthermore, transcriptome analysis was performed to evaluate the putative influence of culture dishes. At steady state, BMDMs cultured on noTC dishes exhibited more proinflammatory gene expression signatures (e.g. IL6, CXCL2 and ILlβ) and functions (e.g. TNF and IL17 signaling pathways). Similar inflammatory responses were observed upon LPS challenge regardless of culture conditions and differentiation factors. However, in LPS treated samples, the difference of gene expression patterns, signaling pathways and molecular functions between TC and noTC cultured BMDMs were largely dependent on the types of growth factors (M-CSF and GM-CSF). This observation might provide valuable information for macrophage studies.
Topics: Animals; Cell Culture Techniques; Edetic Acid; Granulocyte-Macrophage Colony-Stimulating Factor; Lipopolysaccharides; Macrophage Colony-Stimulating Factor; Macrophages; Mice; Phenotype; Trypsin
PubMed: 35874686
DOI: 10.3389/fimmu.2022.920232 -
European Journal of Ophthalmology Jul 2023Descemet´s membrane ruptures (with a discontinuation of Descemet´s membrane and double detached coiled edges) in the context of complicated anterior segment surgery...
PURPOSE
Descemet´s membrane ruptures (with a discontinuation of Descemet´s membrane and double detached coiled edges) in the context of complicated anterior segment surgery have rarely been described and its management can be challenging. We report a modified Descemet stripping only (DSO) technique associated with ripasudil drops to treat these cases when other techniques fail.
METHODS
We describe two cases of large Descemet´s membrane detachments associated with Descemet´s ruptures after cataract surgery that did not respond to two SF intracameral injections. As the detached Descemet's membrane and coiled edges might have prevented endothelial cell migration, we decided to perform a modified DSO with post-operative ripasudil drops to promote corneal clearance.
RESULTS
Both cases improved significantly in unaided and best corrected visual acuity (BCVA), corneal clearance and pachymetry, avoiding the need for an endothelial keratoplasty. Endothelial cells were observed on specular microscopy within the area of the descemetorhexis.
CONCLUSION
DSO with ripasudil drops might be a valuable tool to recover corneal clearance and avoid endothelial keratoplasty in complex Descemet´s membrane detachments with ruptures that do not respond to other treatments.
Topics: Humans; Fuchs' Endothelial Dystrophy; Descemet Membrane; Endothelium, Corneal; Visual Acuity; Endothelial Cells; Descemet Stripping Endothelial Keratoplasty
PubMed: 35435049
DOI: 10.1177/11206721221095598 -
PLoS Pathogens Apr 2008The agr quorum-sensing system of Staphylococcus aureus modulates the expression of virulence factors in response to autoinducing peptides (AIPs). Recent studies have...
The agr quorum-sensing system of Staphylococcus aureus modulates the expression of virulence factors in response to autoinducing peptides (AIPs). Recent studies have suggested a role for the agr system in S. aureus biofilm development, as agr mutants exhibit a high propensity to form biofilms, and cells dispersing from a biofilm have been observed displaying an active agr system. Here, we report that repression of agr is necessary to form a biofilm and that reactivation of agr in established biofilms through AIP addition or glucose depletion triggers detachment. Inhibitory AIP molecules did not induce detachment and an agr mutant was non-responsive, indicating a dependence on a functional, active agr system for dispersal. Biofilm detachment occurred in multiple S. aureus strains possessing divergent agr systems, suggesting it is a general S. aureus phenomenon. Importantly, detachment also restored sensitivity of the dispersed cells to the antibiotic rifampicin. Proteinase K inhibited biofilm formation and dispersed established biofilms, suggesting agr-mediated detachment occurred in an ica-independent manner. Consistent with a protease-mediated mechanism, increased levels of serine proteases were detected in detaching biofilm effluents, and the serine protease inhibitor PMSF reduced the degree of agr-mediated detachment. Through genetic analysis, a double mutant in the agr-regulated Aur metalloprotease and the SplABCDEF serine proteases displayed minimal extracellular protease activity, improved biofilm formation, and a strongly attenuated detachment phenotype. These findings indicate that induction of the agr system in established S. aureus biofilms detaches cells and demonstrate that the dispersal mechanism requires extracellular protease activity.
Topics: Anti-Bacterial Agents; Bacterial Proteins; Biofilms; Endopeptidase K; Enzyme Inhibitors; Gene Expression Regulation, Bacterial; Microbial Sensitivity Tests; Mutation; Peptides, Cyclic; Phenylmethylsulfonyl Fluoride; Serine Endopeptidases; Staphylococcus aureus; Trans-Activators; Transcription, Genetic
PubMed: 18437240
DOI: 10.1371/journal.ppat.1000052