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6,486 result(s) for "Eye Lens"
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Lifetime-scale ontogenetic movement and diets of red grouper inferred using a combination of instantaneous and archival methods
Many predatory marine fishes undergo ontogenetic diet and habitat shifts as they grow. Most fishery datasets, such as catch records, length frequencies, and stomach contents, create a series of snapshots, with each captured fish representing a single timepoint during the lifespan. Chemical archives, such as eye lenses, preserve information regarding several life stages for each individual. By combining these disparate datasets, conclusions are strengthened through weight of evidence. We combined a novel archive, δ13C and δ15N bulk values in sequential eye-lens laminae, with fishery-independent catch records and stomach contents for red grouper Epinephelus morio (Valenciennes 1828) from the eastern Gulf of Mexico, USA. Eye-lens core isotope values suggest that successful individuals spend their larval period on the mid-to-outer continental shelf and locations do not vary substantially year-to-year. Profiles of δ15N values indicate that trophic position increases with size following a logarithmic growth model, while stomach contents indicate a simultaneous increase in fish proportion in the diet. Stomach contents and δ13C values together suggest that most red grouper move to nearshore waters at settlement, spend several months in shallow water with heavy benthic diet dependence, then slowly cross the continental shelf toward deeper water as they mature. With this work, we demonstrate that eye-lens isotope value profiles can enhance fisheries datasets and may provide a method of recreating diet and movement histories for species without long-term biological information.
Proposed New AV-Type Test-Bed for Accurate and Reliable Fish-Eye Lens Camera Self-Calibration
The fish-eye lens camera has a wide field of view that makes it effective for various applications and sensor systems. However, it incurs strong geometric distortion in the image due to compressive recording of the outer part of the image. Such distortion must be interpreted accurately through a self-calibration procedure. This paper proposes a new type of test-bed (the AV-type test-bed) that can effect a balanced distribution of image points and a low level of correlation between orientation parameters. The effectiveness of the proposed test-bed in the process of camera self-calibration was verified through the analysis of experimental results from both a simulation and real datasets. In the simulation experiments, the self-calibration procedures were performed using the proposed test-bed, four different projection models, and five different datasets. For all of the cases, the Root Mean Square residuals (RMS-residuals) of the experiments were lower than one-half pixel. The real experiments, meanwhile, were carried out using two different cameras and five different datasets. These results showed high levels of calibration accuracy (i.e., lower than the minimum value of RMS-residuals: 0.39 pixels). Based on the above analyses, we were able to verify the effectiveness of the proposed AV-type test-bed in the process of camera self-calibration.
Protective Efficacy of Different Ocular Radiation Protection Devices: A Phantom Study
PurposeThe aim of this study was to investigate the efficacy of different designs and types of ocular radiation protection devices depending on simulated varied body heights in a phantom-simulated thoracic intervention.Materials and MethodsA clinical angiography system with a standardized fluoroscopy protocol with an anthropomorphic chest phantom as a scattering object and optically stimulated luminescence dosimeters for measuring radiation dose were used. The dosimeters were placed at the position of eyes of an anthropomorphic head phantom simulating the examiner. The head phantom was placed on a height-adjustable stand simulating the height of the examiner from 160 to 200 cm with 10 cm increments. The dose values were then measured with no radiation protection, a weightless-like radiation protection garment, radiation protection glasses and visors.ResultsThe average dose reduction using radiation protection devices varied between 57.7 and 83.4% (p < 0.05) in comparison with no radiation protection. Some radiation protection glasses and visors showed a significant dose reduction for the eye lenses when the height of the examiner increased. The right eye was partially less protected, especially if the distances between the simulated examiner’s head and the scatter object were small.ConclusionAll the investigated protection devices showed a significant reduction in radiation exposure to the simulated examiner. For some devices, the radiation dose increased with decreasing distance to the scattering object, especially for the right eye lens.
Effectiveness of Radiation Protection Caps for Lowering dose to the Brain and the Eye Lenses
PurposeThis work was designed to study the effectiveness of radiation protection caps in lowering the dose to the brain and the eye lens during fluoroscopically guided interventions.Materials and MethodsTwo types of radiation protection caps were examined with regards to their capacity to lower the radiation dose. One cap is equipped with lateral flaps, the other one is not. These caps were fitted to the head of an anthropomorphic Alderson-Rando (A.-R.) phantom. The phantom was positioned aside an angiographic table simulating the position of the first operator during a peripheral arterial intervention. One of the brain slices and both eyes of the A.-R. phantom were equipped with thermoluminescence dosimeters (TLDs).ResultsThe analysis of the data showed that the cap without lateral flaps reduced the dose to the brain by 11,5–27,5 percent depending on the position within the brain. The cap with lateral protection flaps achieved a shielding effect between 44,7 and 78,9 percent. When evaluating the dose to the eye, we did see an increase of dose reduction from 63,3 to 66,5 percent in the left eye and from 45,8 to 46,8 percent in the right eye for the cap without lateral protection. When wearing the cap with lateral protection we observed an increase of dose reduction from 63,4 to 67,2 percent in the left eye and from 45,8 to 50,0 percent in the right eye.ConclusionRadiation protection caps can be an effective tool to reduce the dose to the brain and the eyes.
Evaluation of Lens Doses among Medical Staff Involved in Nuclear Medicine: Current Eye Radiation Exposure among Nuclear-Medicine Staff
The International Commission on Radiological Protection has lowered the annual equivalent eye-lens dose to 20 mSv. Although occupational exposure can be high in nuclear medicine (NM) departments, few studies have been conducted regarding eye-lens exposure among NM staff. This study aimed to estimate the annual lens doses of staff in an NM department and identify factors contributing to lens exposure. Four nurses and six radiographers performing positron emission tomography (PET) examinations and four radiographers performing radioisotope (RI) examinations (excluding PET) were recruited for this study. A lens dosimeter was attached near the left eye to measure the 3-mm-dose equivalent; a personal dosimeter was attached to the left side of the neck to measure the 1-cm- and 70-µm-dose equivalents. Measurements were acquired over six months, and the cumulative lens dose was doubled to derive the annual dose. Correlations between the lens and personal-dosimeter doses, between the lens dose and the numbers of procedures, and between the lens dose and the amounts of PET drugs (radiopharmaceuticals) injected were examined. Wilcoxon’s signed-rank test was used to compare lens and personal-dosimeter doses. The estimated annual doses were 0.93 ± 0.13 mSv for PET nurses, 0.71 ± 0.41 mSv for PET radiographers, and 1.10 ± 0.53 mSv for RI radiographers. For PET nurses, but not for PET or RI radiographers, there was a positive correlation between the numbers of procedures and lens doses and between amounts injected and lens doses. There was a significant difference between the lens and personal-dosimeter doses of PET nurses. The use of protective measures, such as shielding, should prevent NM staff from receiving lens doses > 20 mSv/year. However, depending on the height of the protective shield, PET nurses may be unable to assess the lens dose accurately using personal dosimeters.
A multicenter study of radiation doses to the eye lenses of clinical physicians performing radiology procedures in Japan
Purpose We investigated occupational dose to the lens of the eye for physicians engaged in radiology procedures. We evaluated the potential for compliance with the new‐equivalent dose limits to the lens of the eye. Further, a “multiple radiation protection” protocol was proposed according to the basic principles of occupational health, and its effectiveness was estimated. Methods Physicians engaged in radiology procedure at medical facilities in Japan were included in this study. The eye lens dose (3‐mm dose equivalent: Hp(3)) for each participant was measured using a small radio‐photoluminescence glass dosimeter mounted on lead glasses. Physicians were directed to procedure multiple radiation protection measures to evaluate their usefulness. Results The Hp(3) was reduced by multiple radiation protection in all physicians. In particular, the Hp(3) reduced from 207.7 to 43.2 μSv/procedure and from 21.6 to 10.2 μSv/procedure in cardiovascular internal physician and cerebrovascular physician, respectively, after the implementation of the proposed multiple radiation protection measures. The dose reduction rate of these measures was 53% (range: 37%–79%). Conclusions The radiation doses received by the eye lenses of physicians engaged in radiology procedure may exceed the dose limits to the lens of the eye if radio‐protective equipment and imaging conditions are not properly controlled. However, based on the lens equivalent dose data, the implementation of “multiple radiation protection” according to the basic principles of occupational health can ensure compliance with the new‐equivalent dose limits to the lens of the eye without placing an undue burden on individual physicians or medical facilities.
Occupational exposure to ionizing radiation and lens opacity in interventional cardiologists
Interventional cardiologists (ICs) are occupationally exposed to low or moderate doses of ionizing radiation from repeated exposures. It is not clear whether these occupational conditions may affect their eye lens. Therefore, the risk of radiation-induced cataract in the cohort of Polish interventional cardiologists is analyzed in this paper. The study group consisted of 69 interventional cardiologists and 78 control individuals occupationally unexposed to ionizing radiation. The eye lens opacities were examined using a slit camera and evaluated with Lens Opacities Grading System III. Cumulative eye lens doses were estimated retrospectively using a questionnaire including data on occupational history. The average cumulative dose to the left and right eye lens of the ICs was 224 mSv and 85 mSv, respectively. Nuclear opalescence and nuclear color opacities in the most exposed left eye were found in 38% of the ICS for both types, and in 47% and 42% of the controls, respectively. Cortical opacities were found in 25% of the ICS and 29% of the controls. Posterior subcapsular opacities were rare: about 7% in the ICs group and 6% in the control group. Overall, there was some, but statistically insignificant, increase in the risk for opacity in the ICs group, relative to the control group, after adjusting for the subjects' age, gender, smoking status and medical exposure (adjusted OR = 1.47, 95% CI: 0.62-3.59 for the pooled \"any-eye any-type\" opacity). There was also no evidence for an increased opacity risk with an increase in the dose. The study found no statistically significant evidence against the hypothesis that the risk of cataract in the group of the ICs occupationally exposed to low doses of ionizing radiation is the same as in the control group. Nevertheless, the adverse effect of ionizing radiation still cannot be excluded due to a relatively small study sample size. Int J Occup Med Environ Health. 2019;32(5):663-75.
Mini-αA-Crystallin Stifled Melittin-Induced Haemolysis and Lymphocyte Lysis
Melittin, the most potent pharmacological ingredient of honey bee venom, induces haemolysis, lymphocyte lysis, long-term pain, localised inflammation, and hyperalgesia. In this study, efforts were made to subdue the melittin’s ill effects using a chaperone peptide called ‘mini-αA-crystallin’ (MAC) derived from eye lens αA-crystallin. Haemolytic test on human red blood cells, percentage viability, and DNA diffusion assay on Human peripheral blood lymphocytes (HPBLs) were performed with melittin in the presence or absence of MAC. Propidium iodide and Annexin V-FITC dual staining were performed to analyse quantitative levels of necrotic and apoptotic induction by melittin in the presence or absence of MAC on HPBLs using a flow cytometer. A computational study to find out the interactions between MAC and melittin was undertaken by modelling the structure of MAC using a PEP-FOLD server. The result showed that MAC inhibited melittin-induced lysis in nucleated (lymphocytes) and enucleated (RBC) cells. Flow cytometric analysis revealed a substantial increase in the necrotic and late apoptotic cells after treating HPBLs with melittin (4 µg/ml) for 24 h. Treatment with MAC at a 2:1 molar ratio prevented HPBLs from developing melittin-induced necrosis and late apoptosis. In the docking study, hydrogen, van der Waals, π-π stacking, and salt bridges were observed between the MAC and melittin complex, confirming a strong interaction between them. The MAC-melittin complex was stable during molecular dynamics simulation. These findings may be beneficial in developing a medication for treating severe cases of honeybee stings.
Homeostasis in the vertebrate lens: mechanisms of solute exchange
The eye lens is avascular, deriving nutrients from the aqueous and vitreous humours. It is, however, unclear which mechanisms mediate the transfer of solutes between these humours and the lens' fibre cells (FCs). In this review, we integrate the published data with the previously unpublished ultrastructural, dye loading and magnetic resonance imaging results. The picture emerging is that solute transfer between the humours and the fibre mass is determined by four processes: (i) paracellular transport of ions, water and small molecules along the intercellular spaces between epithelial and FCs, driven by Na+-leak conductance; (ii) membrane transport of such solutes from the intercellular spaces into the fibre cytoplasm by specific carriers and transporters; (iii) gap-junctional coupling mediating solute flux between superficial and deeper fibres, Na+/K+-ATPase-driven efflux of waste products in the equator, and electrical coupling of fibres; and (iv) transcellular transfer via caveoli and coated vesicles for the uptake of macromolecules and cholesterol. There is evidence that the Na+-driven influx of solutes occurs via paracellular and membrane transport and the Na+/K+-ATPase-driven efflux of waste products via gap junctions. This micro-circulation is likely restricted to the superficial cortex and nearly absent beyond the zone of organelle loss, forming a solute exchange barrier in the lens.
Occupational Radiation Dose to Eye Lenses in CT-Guided Interventions Using MDCT-Fluoroscopy
In computed tomography (CT)-guided interventions (CTIs), physicians are close to a source of scattered radiation. The physician and staff are at high risk of radiation-induced injury (cataracts). Thus, dose-reducing measures for physicians are important. However, few previous reports have examined radiation doses to physicians in CTIs. This study evaluated the radiation dose to the physician and medical staff using multi detector (MD)CT-fluoroscopy, and attempted to understand radiation-protection and -reduction methods. The procedures were performed using an interventional radiology (IVR)-CT system. We measured the occupational radiation dose (physician and nurse) using a personal dosimeter in real-time, gathered CT-related parameters (fluoroscopy time, mAs, CT dose index (CTDI), and dose length product (DLP)), and performed consecutive 232 procedures in CT-guided biopsy. Physician doses (eye lens, neck, and hand; μSv, average ± SD) in our CTIs were 39.1 ± 36.3, 23.1 ± 23.7, and 28.6 ± 31.0, respectively. Nurse doses (neck and chest) were lower (2.3 ± 5.0 and 2.4 ± 4.4, respectively) than the physician doses. There were significant correlations between the physician doses (eye and neck) and related factors, such as CT-fluoroscopy mAs (eye dose: r = 0.90 and neck dose: r = 0.83). We need to understand the importance of reducing/optimizing the dose to the physician and medical staff in CTIs. Our study suggests that physician and staff doses were not significant when the procedures were performed with the appropriate radiation protection and low-dose techniques.