Publications by authors named "Efren Gonzalez"

9 Publications

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Retinopathy of prematurity screening and risk mitigation during the COVID-19 pandemic.

J AAPOS 2021 Apr 18. Epub 2021 Apr 18.

Boston Children's Hospital, Boston, Massachusetts;; Harvard Medical School, Boston, Massachusetts.

Background: The coronavirus disease 2019 (COVID-19) pandemic has significantly disrupted the delivery of healthcare. Although most nonurgent ophthalmology visits at Boston Children's Hospital were canceled, premature infants at risk for retinopathy of prematurity (ROP) still required timely, in-person care during the initial 3-month period of the infection surge in Massachusetts. The purpose of the current study was to report our protocols for mitigating risk of exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) between infants and eye care providers and to compare examination rates and results with the same 3-month period in 2019.

Methods: During the infection surge, we added new infection control measures and strengthened existing ones. Additional personal protective equipment was used, and the number of ophthalmologists rotating in the three high-capacity NICUs we service was limited.

Results: More infants required ROP examinations during the study period in 2020 than in the same period in 2019, but fewer examinations were performed. There were no cases of missed progression to severe ROP during this time and no known transmission of SARS-CoV-2 between ROP patients and ophthalmology staff.

Conclusions: Overall, effective ROP care was safely provided during the COVID-19 pandemic, and contact with this vulnerable population was minimized.
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http://dx.doi.org/10.1016/j.jaapos.2020.11.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8053364PMC
April 2021

TRIPP Is a Plant-Specific Component of the Arabidopsis TRAPPII Membrane Trafficking Complex with Important Roles in Plant Development.

Plant Cell 2020 07 5;32(7):2424-2443. Epub 2020 May 5.

Department of Plant Biology, Carnegie Institution for Science, Stanford, California 94305

How the membrane trafficking system spatially organizes intracellular activities and intercellular signaling networks in plants is not well understood. Transport Protein Particle (TRAPP) complexes play key roles in the selective delivery of membrane vesicles to various subcellular compartments in yeast and animals but remain to be fully characterized in plants. Here, we investigated TRAPP complexes in Arabidopsis () using immunoprecipitation followed by quantitative mass spectrometry analysis of AtTRS33, a conserved core component of all TRAPP complexes. We identified 14 AtTRS33-interacting proteins, including homologs of all 13 TRAPP components in mammals and a protein that has homologs only in multicellular photosynthetic organisms and is thus named TRAPP-Interacting Plant Protein (TRIPP). TRIPP specifically associates with the TRAPPII complex through binary interactions with two TRAPPII-specific subunits. TRIPP colocalized with a subset of TRS33 compartments and -Golgi network markers in a TRS33-dependent manner. Loss-of-function mutants exhibited dwarfism, sterility, partial photomorphogenesis in the dark, reduced polarity of the auxin transporter PIN2, incomplete cross wall formation, and altered localization of a TRAPPII-specific component. Therefore, TRIPP is a plant-specific component of the TRAPPII complex with important functions in trafficking, plant growth, and development.
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http://dx.doi.org/10.1105/tpc.20.00044DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7346556PMC
July 2020

Global Retinoblastoma Presentation and Analysis by National Income Level.

JAMA Oncol 2020 05;6(5):685-695

Imam Hussein Cancer Center, Karbala, Iraq.

Importance: Early diagnosis of retinoblastoma, the most common intraocular cancer, can save both a child's life and vision. However, anecdotal evidence suggests that many children across the world are diagnosed late. To our knowledge, the clinical presentation of retinoblastoma has never been assessed on a global scale.

Objectives: To report the retinoblastoma stage at diagnosis in patients across the world during a single year, to investigate associations between clinical variables and national income level, and to investigate risk factors for advanced disease at diagnosis.

Design, Setting, And Participants: A total of 278 retinoblastoma treatment centers were recruited from June 2017 through December 2018 to participate in a cross-sectional analysis of treatment-naive patients with retinoblastoma who were diagnosed in 2017.

Main Outcomes And Measures: Age at presentation, proportion of familial history of retinoblastoma, and tumor stage and metastasis.

Results: The cohort included 4351 new patients from 153 countries; the median age at diagnosis was 30.5 (interquartile range, 18.3-45.9) months, and 1976 patients (45.4%) were female. Most patients (n = 3685 [84.7%]) were from low- and middle-income countries (LMICs). Globally, the most common indication for referral was leukocoria (n = 2638 [62.8%]), followed by strabismus (n = 429 [10.2%]) and proptosis (n = 309 [7.4%]). Patients from high-income countries (HICs) were diagnosed at a median age of 14.1 months, with 656 of 666 (98.5%) patients having intraocular retinoblastoma and 2 (0.3%) having metastasis. Patients from low-income countries were diagnosed at a median age of 30.5 months, with 256 of 521 (49.1%) having extraocular retinoblastoma and 94 of 498 (18.9%) having metastasis. Lower national income level was associated with older presentation age, higher proportion of locally advanced disease and distant metastasis, and smaller proportion of familial history of retinoblastoma. Advanced disease at diagnosis was more common in LMICs even after adjusting for age (odds ratio for low-income countries vs upper-middle-income countries and HICs, 17.92 [95% CI, 12.94-24.80], and for lower-middle-income countries vs upper-middle-income countries and HICs, 5.74 [95% CI, 4.30-7.68]).

Conclusions And Relevance: This study is estimated to have included more than half of all new retinoblastoma cases worldwide in 2017. Children from LMICs, where the main global retinoblastoma burden lies, presented at an older age with more advanced disease and demonstrated a smaller proportion of familial history of retinoblastoma, likely because many do not reach a childbearing age. Given that retinoblastoma is curable, these data are concerning and mandate intervention at national and international levels. Further studies are needed to investigate factors, other than age at presentation, that may be associated with advanced disease in LMICs.
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http://dx.doi.org/10.1001/jamaoncol.2019.6716DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7047856PMC
May 2020

Foucault test: a quantitative evaluation method.

J Opt Soc Am A Opt Image Sci Vis 2016 Aug;33(8):1604-11

Reliable and accurate testing methods are essential to guiding the polishing process during the figuring of optical telescope mirrors. With the natural advancement of technology, the procedures and instruments used to carry out this delicate task have consistently increased in sensitivity, but also in complexity and cost. Fortunately, throughout history, the Foucault knife-edge test has shown the potential to measure transverse aberrations in the order of the wavelength, mainly when described in terms of physical theory, which allows a quantitative interpretation of its characteristic shadowmaps. Our previous publication on this topic derived a closed mathematical formulation that directly relates the knife-edge position with the observed irradiance pattern. The present work addresses the quite unexplored problem of the wavefront's gradient estimation from experimental captures of the test, which is achieved by means of an optimization algorithm featuring a proposed ad hoc cost function. The partial derivatives thereby calculated are then integrated by means of a Fourier-based algorithm to retrieve the mirror's actual surface profile. To date and to the best of our knowledge, this is the very first time that a complete mathematical-grounded treatment of this optical phenomenon is presented, complemented by an image-processing algorithm which allows a quantitative calculation of the corresponding slope at any given point of the mirror's surface, so that it becomes possible to accurately estimate the aberrations present in the analyzed concave device just through its associated foucaultgrams.
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http://dx.doi.org/10.1364/JOSAA.33.001604DOI Listing
August 2016

Regularized quadratic cost-function for integrating wave-front gradient fields.

Opt Lett 2016 May;41(10):2314-7

From the Bayesian regularization theory we derive a quadratic cost-function for integrating wave-front gradient fields. In the proposed cost-function, the term of conditional distribution uses a central-differences model to make the estimated function well consistent with the observed gradient field. As will be shown, the results obtained with the central-differences model are superior to the results obtained with the backward-differences model, commonly used in other integration techniques. As a regularization term we use an isotropic first-order differences Markov Random-Field model, which acts as a low-pass filter reducing the errors caused by the noise. We present simulated and real experiments of the proposal applied in the Foucault test, obtaining good results.
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http://dx.doi.org/10.1364/OL.41.002314DOI Listing
May 2016

Foucault test: shadowgram modeling from the physical theory for quantitative evaluations.

J Opt Soc Am A Opt Image Sci Vis 2014 Dec;31(12):2719-22

The physical theory of the Foucault test has been investigated to represent the complex amplitude and irradiance of the shadowgram in terms of the wavefront error; however, most of the studies have limited the treatment for the particular case of nearly diffraction-limited optical devices (i.e., aberrations smaller than the wavelength). In this paper we discard this restriction, and in order to show a more precise interpretation from the physical theory we derive expressions for the complex amplitude and the irradiance over an optical device with larger aberrations. To the best of our knowledge, it is the first time an expression is obtained in closed form. As will be seen, the result of this derivation is obtained using some properties of the Hilbert transform that permit representing the irradiance in a simple form in terms of the partial derivatives of the wavefront error. Additionally, we briefly describe from this point of view a methodology for the quantitative analysis of the test.
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http://dx.doi.org/10.1364/JOSAA.31.002719DOI Listing
December 2014

Efficacy of surgical simulator training versus traditional wet-lab training on operating room performance of ophthalmology residents during the capsulorhexis in cataract surgery.

J Cataract Refract Surg 2013 Nov;39(11):1734-41

From the Veterans Affairs Boston Healthcare System (Daly, Gonzalez, Siracuse-Lee) and the Departments of Ophthalmology, Boston University School of Medicine (Daly, Siracuse-Lee) and Harvard Medical School (Daly, Gonzalez), Boston, Massachusetts, USA. Electronic address:

Purpose: To compare the operating room performance of ophthalmology residents trained by traditional wet-lab versus surgical simulation on the continuous curvilinear capsulorhexis (CCC) portion of cataract surgery.

Setting: Academic tertiary referral center.

Design: Prospective randomized study.

Methods: Residents who chose to participate and provided informed consent were randomized to preoperative CCC training in the wet lab or on a simulator. Residents completed pre-practice demographic questionnaires including habits of daily living. After completion of their preoperative training (wet lab versus simulator), residents performed their first CCC of the clinical rotation under the direct supervision of an attending physician as part of their standard training at the facility. Residents then completed satisfaction questionnaires regarding their preoperative training. Two attending surgeons reviewed and graded each video of operating room performance. The mean score between the 2 attending physicians was used as the individual performance score for each of the 12 performance criteria. The overall score was calculated as the sum of these 12 individual performance scores (standardized).

Results: Ten residents trained in the wet lab and 11 on the simulator. There was no significant difference in overall score between the 2 groups (P=.608). There was no significant difference in any individual score except time (wet-lab group faster than simulator group) (P=.038).

Conclusions: Preoperative simulator training prepared residents for the operating room as effectively as the wet lab. The time to pass the simulator curriculum was predictive of the time and overall performance in the operating room.

Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned.
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http://dx.doi.org/10.1016/j.jcrs.2013.05.044DOI Listing
November 2013

Hand-held high-resolution spectral domain optical coherence tomography in retinoblastoma: clinical and morphologic considerations.

Br J Ophthalmol 2013 Jan 26;97(1):59-65. Epub 2012 Oct 26.

Department of Ophthalmology and Vision Sciences, The Hospital for Sick Children, 555 University Ave, Toronto, Ontario, Canada M5G 2M9.

Purpose: Hand-held spectral domain optical coherence tomography (HHSD OCT) has greatly expanded the imaging/diagnostic capacity for clinicians managing children with intraocular retinoblastoma. We present our early experience with HHSD OCT and conventional spectral domain OCT imaging in these patients.

Methods: In this retrospective cross-sectional observational study, infants were imaged during examination under anaesthesia with HHSD OCT in the supine position. Older cooperative retinoblastoma patients were additionally imaged with upright conventional OCT. Clinical data were derived from patient charts and from a prospectively maintained interinstitutional retinoblastoma database. Complementary imaging techniques, including RetCam™, fluorescein angiography and B-scan ultrasound, were assessed.

Results: Twenty-two intraocular lesions in 16 patients were imaged. HHSD OCT was used exclusively in 19 lesions, while conventional OCT was also performed in three cases. Small lesions were imaged in five cases, all of which were localised to the middle retinal layers. Clinical uses for HHSD OCT imaging identified included: diagnosis of new lesions, monitoring response to laser therapy and the identification of edge recurrences.

Conclusions: Although indirect ophthalmoscopy remains the gold standard for diagnosis and treatment of retinoblastoma, HHSD OCT is a valuable tool in better understanding and managing retinoblastoma.
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http://dx.doi.org/10.1136/bjophthalmol-2012-302133DOI Listing
January 2013

Semi-Huber potential function for image segmentation.

Opt Express 2012 Mar;20(6):6542-54

Unidad Academica de Ingenieriıa Electrica, Universidad Autonoma de Zacatecas, Av. Lopez Velarde 801, Col. Centro, C. P. 98000, Zacatecas, Zacatecas, Mexico.

In this work, a novel model of Markov Random Field (MRF) is introduced. Such a model is based on a proposed Semi-Huber potential function and it is applied successfully to image segmentation in presence of noise. The main difference with respect to other half-quadratic models that have been taken as a reference is, that the number of parameters to be tuned in the proposed model is smaller and simpler. The idea is then, to choose adequate parameter values heuristically for a good segmentation of the image. In that sense, some experimental results show that the proposed model allows an easier parameter adjustment with reasonable computation times.
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http://dx.doi.org/10.1364/OE.20.006542DOI Listing
March 2012