Holographic UV laser microsurgery.
Ontology highlight
ABSTRACT:
SUBMITTER: Jayasinghe AK
PROVIDER: S-EPMC3184868 | biostudies-other | 2011 Sep
REPOSITORIES: biostudies-other
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Project description:We report on experiments directly in living cells that reveal the regulation of kinetochore function by tension. X and Y sex chromosomes in crane fly (Nephrotoma suturalis) spermatocytes exhibit an atypical segregation mechanism in which each univalent maintains K-fibers to both poles. During anaphase, each maintains a leading fiber (which shortens) to one pole and a trailing fiber (which elongates) to the other. We used this intriguing behavior to study the motile states that X-Y kinetochores are able to support during anaphase. We used a laser microbeam to either sever a univalent along the plane of sister chromatid cohesion or knock out one of a univalent's two kinetochores to release one or both from the resistive influence of its sister's K-fiber. Released kinetochores with attached chromosome arms moved poleward at rates at least two times faster than normal. Furthermore, fluorescent speckle microscopy revealed that detached kinetochores converted their functional state from reverse pac-man to pac-man motility as a consequence of their release from mechanical tension. We conclude that kinetochores can exhibit pac-man motility, even though their normal behavior is dominated by traction fiber mechanics. Unleashing of kinetochore motility through loss of resistive force is further evidence for the emerging model that kinetochores are subject to tension-sensitive regulation.
| S-EPMC3418308 | biostudies-literature
Project description:Accurate chromosome segregation depends on proper kinetochore-microtubule attachment. Upon microtubule interaction, kinetochores are subjected to forces generated by the microtubules. In this work, we used laser ablation to sever microtubules attached to a merotelic kinetochore, which is laterally stretched by opposing pulling forces exerted by microtubules, and inferred the mechanical response of the kinetochore from its length change. In both mammalian PtK1 cells and in the fission yeast Schizosaccharomyces pombe, kinetochores shortened after microtubule severing. Interestingly, the inner kinetochore-centromere relaxed faster than the outer kinetochore. Whereas in fission yeast all kinetochores relaxed to a similar length, in PtK1 cells the more stretched kinetochores remained more stretched. Simple models suggest that these differences arise because the mechanical structure of the mammalian kinetochore is more complex. Our study establishes merotelic kinetochores as an experimental model for studying the mechanical response of the kinetochore in live cells and reveals a viscoelastic behavior of the kinetochore that is conserved in yeast and mammalian cells.
| S-EPMC4810299 | biostudies-literature
Project description:Transoral laser microsurgery (TLM) is an accepted and effective treatment strategy for supraglottic carcinomas. Early supraglottic carcinoma has excellent outcomes independently of the treatment approach. The role of TLM for the treatment of locally advanced tumors is debated. Particularly, the functional outcomes after TLM have to be proven by functional assessment of large cohorts of patients. This study analyzes the oncologic and functional outcomes after TLM for supraglottic carcinomas.Ninety-one patients with pT1-pT4a supraglottic carcinomas treated between January 2002 and December 2012 were analyzed. Distribution of tumors (UICC 2010) was 11 patients with pT1, 31 patients with pT2, 36 patients with pT3, and 13 patients with pT4a tumors. Node status was positive in 40 (43.6%) patients; 61 (67.1%) patients had stage III or IVa disease. Local control and survival were estimated using the Kaplan-Meier method. For the assessment of functional outcomes, the MD Anderson Dysphagia Inventory (MDADI), the Voice Handicap Index-10 (VHI-10), and the performance status scale for head and neck cancer [Performance Status Scale for Head and Neck (PSS-HN)] were used.The median age was 62 years (range, 33-88 years). Fourteen (15.4%) patients developed a local or locoregional recurrence. The 5-year local control rate and 5-year ultimate local control rate were 72 and 92%, respectively. The 5-year overall survival rate was 63%. Twelve (13.2%) patients needed temporary tracheostomy. Sixty-eight (74.0%) patients had a nasogastric feeding tube post-operatively. At 1-year post-operative follow-up, only three patients were PEG dependent. The median VHI-10 score was 35, the median MDADI composite score was 80, and the median score of the domain "normalcy of diet" in the PSS-HN was 91.The oncologic outcomes are comparable to the results of open surgery for early and advanced supraglottic carcinomas. Functional swallowing outcome is superior to open surgery and to concomitant chemoradiation. Patients treated with TLM perceive low levels of voice- and swallowing-related quality of life impairment.
| S-EPMC5954241 | biostudies-other
Project description:A metasurface hologram combines fine spatial resolution and large viewing angles with a planar form factor and compact size. However, it suffers coherent artifacts originating from electromagnetic cross-talk between closely packed meta-atoms and fabrication defects of nanoscale features. Here, we introduce an efficient method to suppress all artifacts by fine-tuning the spatial coherence of illumination. Our method is implemented with a degenerate cavity laser, which allows a precise and continuous tuning of the spatial coherence over a wide range, with little variation in the emission spectrum and total power. We find the optimal degree of spatial coherence to suppress the coherent artifacts of a meta-hologram while maintaining the image sharpness. This work paves the way to compact and dynamical holographic displays free of coherent defects.
| S-EPMC8134448 | biostudies-literature
Project description:The development of accurate and rapid techniques to produce nanophotonic structures is essential in data storage, sensors, and spectroscopy. Existing bottom-up and top-down approaches to fabricate nanophotonic devices are high cost and time consuming, limiting their mass manufacturing and practical applications. Here, we demonstrate a strategy to rapidly create 25-40 nm thick 1/2D Au-Ti nanopatterns using holographic direct laser interference patterning (DLIP). Pulses of an Nd:YAG laser (1064 nm) in holographic Denisyuk reflection mode were used to create ablative interference fringes. The constructive interference antinode regions of the standing wave selectively ablated a Au-Ti layer in localized regions to controllably form nanogratings. Varying the laser exposure parameters allowed for rapid patterning of 2D square and rectangular arrays within seconds. Controlling the distances between the laser source, recording medium, and the object, allowed for achieving a 2D spatial grating periodicity of 640 nm × 640 nm. Diffracted and transmitted light spectra of 2D nanostructure arrays were analyzed using angle-resolved measurements and spectroscopy.
| S-EPMC5171911 | biostudies-literature
Project description:The impact of mechanical forces on kinetochore motility was investigated using laser microsurgery to detach kinetochores with associated chromatin (K fragment) from meiotic chromosomes in spermatocytes from the crane fly Nephrotoma suturalis. In spermatocytes, elastic tethers connect telomeres of homologues during anaphase A of meiosis I, thus preventing complete disjunction until mid- to late anaphase A. K fragments liberated from tethered arms moved at twice the normal velocity toward their connected poles. To assess functional states of detached and control kinetochores, we loaded cells with fluorescently labeled tubulin for fluorescent speckle microscopy on kinetochore microtubules. Control kinetochores added fluorescent speckles at the kinetochore during anaphase A, whereas kinetochores of K fragments generally did not. In cases in which speckles reappeared in K-fragment K fibers, speckles and K fragments moved poleward at similar velocities. Thus detached kinetochores convert from their normal polymerization (reverse pac-man) state to a different state, in which polymerization is not evident. We suggest that the converted state is "park," in which kinetochores are anchored to plus ends of kinetochore microtubules that shorten exclusively at their polar ends.
| S-EPMC3237623 | biostudies-literature
Project description:BackgroundTransoral laser microsurgery has been suggested as an alternative treatment modality for hypopharyngeal carcinoma. The purpose of this study is to systematically review the oncologic and functional outcomes of patients with hypopharyngeal carcinoma when treated with primary transoral laser microsurgery.MethodsA comprehensive literature search was performed using PRISMA methodology on OVID MEDLINE and EMBASE. Meta-analysis was completed for oncological outcomes.ResultsSix studies reported quality of life outcomes five reported oncologic outcomes. A median of 95% (range 0.83-0.98) patients achieving gastrostomy independence, a median of 3% (range 0%-6%) were tracheostomy dependent, and a median of 97% (Range 0.89-1.0) were able to preserve their larynx. Pooled five-year overall survival was 54% (CI, 0.50-0.58, I2 = 29%), pooled disease-specific survival was 72% (CI, 0.68-0.77, I2 = 46%), and pooled local control rate was 78% (CI, 0.72-0.85, I2 = 69%).ConclusionSystematic review supports improvements in functional outcomes and oncologic outcomes with transoral laser microsurgery.
| S-EPMC7042655 | biostudies-literature
Project description:Laser microsurgery and finite element modeling are used to determine the cell-level mechanics of the amnioserosa-a morphogenetically crucial epithelium on the dorsal surface of fruit fly embryos (Drosophila melanogaster). In the experiments, a tightly focused laser ablates a subcellular hole (1 microm in diameter) that passes clean through the epithelium. The surrounding cells recoil from the wound site with a large range of initial recoil velocities. These depend on the embryo's developmental stage and the subcellular wound site. The initial recoil (up to 0.1 s) is well reproduced by a base finite element model, which assumes a uniform effective viscosity inside the cells, a constant tension along each cell-cell boundary, and a large, potentially anisotropic, far-field stress--one that far exceeds the stress equivalent of the cell-edge tensions. After 0.1 s, the experimental recoils slow dramatically. This observation can be reproduced by adding viscoelastic rods along cell edges or as a fine prestressed mesh parallel to the apical and basal membranes of the cell. The mesh also reproduces a number of double-wounding experiments in which successive holes are drilled in a single cell.
| S-EPMC2793361 | biostudies-literature
Project description:Laser microsurgery is the current gold standard surgical technique for the treatment of selected diseases in delicate organs such as the larynx. However, the operations require large surgical expertise and dexterity, and face significant limitations imposed by available technology, such as the requirement for direct line of sight to the surgical field, restricted access, and direct manual control of the surgical instruments. To change this status quo, the European project μRALP pioneered research towards a complete redesign of current laser microsurgery systems, focusing on the development of robotic micro-technologies to enable endoscopic operations. This has fostered awareness and interest in this field, which presents a unique set of needs, requirements and constraints, leading to research and technological developments beyond μRALP and its research consortium. This paper reviews the achievements and key contributions of such research, providing an overview of the current state of the art in robot-assisted endoscopic laser microsurgery. The primary target application considered is phonomicrosurgery, which is a representative use case involving highly challenging microsurgical techniques for the treatment of glottic diseases. The paper starts by presenting the motivations and rationale for endoscopic laser microsurgery, which leads to the introduction of robotics as an enabling technology for improved surgical field accessibility, visualization and management. Then, research goals, achievements, and current state of different technologies that can build-up to an effective robotic system for endoscopic laser microsurgery are presented. This includes research in micro-robotic laser steering, flexible robotic endoscopes, augmented imaging, assistive surgeon-robot interfaces, and cognitive surgical systems. Innovations in each of these areas are shown to provide sizable progress towards more precise, safer and higher quality endoscopic laser microsurgeries. Yet, major impact is really expected from the full integration of such individual contributions into a complete clinical surgical robotic system, as illustrated in the end of this paper with a description of preliminary cadaver trials conducted with the integrated μRALP system. Overall, the contribution of this paper lays in outlining the current state of the art and open challenges in the area of robot-assisted endoscopic laser microsurgery, which has important clinical applications even beyond laryngology.
| S-EPMC8455830 | biostudies-literature
Project description:ObjectiveTo determine the 5-year survival outcomes of patients with oropharyngeal cancer treated with transoral laser microsurgery at our institution.MethodsA prospective longitudinal cohort study of all cases of oropharyngeal squamous cell cancer or clinically unknown primaries diagnosed at our institution between September 1, 2014, to December 31, 2019, treated with primary transoral laser microsurgery were analyzed. Patients with a previous history of head and neck radiation were excluded from analysis. Kaplan-Meier survival curves were used to estimate 5-year overall survival, disease-specific survival, local control, and recurrence free survival rates in oropharyngeal squamous cell carcinoma.ResultsOf 142 patients identified, 135 met criteria and were included in the survival analysis. Five-year local control rates in p16 positive and negative disease were 99.2% and 100%, respectively, with one locoregional failure in the p16 positive cohort. Five-year overall survival, disease-specific survival, and recurrence free survival in p16 positive disease were 91%, 95.2%, and 87% respectively (n = 124). Five-year overall survival, disease-specific survival, and recurrence free survival in p16 negative disease were 39.8%, 58.3%, and 60%, respectively (n = 11). The permanent gastrostomy tube rate was 1.5% and zero patients received a tracheostomy at the time of surgery. One patient (0.74%) required a return to the OR for a post-operative pharyngeal bleed.ConclusionTransoral laser microsurgery is a safe primary treatment option for oropharyngeal squamous cell carcinoma with high 5-year survival outcomes, notably in p16 positive disease. More randomized trials are needed to compare survival outcomes and associated morbidity in transoral laser microsurgery compared to treatment with primary chemoradiation.Level of evidence3.
| S-EPMC9948578 | biostudies-literature