Santiago Costantino

Université de Montréal | UdeM · Department of Ophthalmology

Purpose The development of neuro-ophthalmic symptoms during long-duration spaceflight presents major risks to astronauts and their missions. Amid efforts to understand spaceflight associated neuro-ocular syndrome (SANS), uncovering the role of the choroid in its etiology is challenged by the accuracy of image segmentation. The present study extends...

Purpose To assess the relationship between the pulsatile choroidal volume change (ΔV) and ocular rigidity (OR), an important biomechanical property of the eye. Design This is a prospective cross-sectional study. Subjects Two hundred seventeen participants (235 eyes) were included in this study. Of those, 18 eyes (18 participants) had exudative re...

This study investigated the effect of intraocular pressure (IOP) reduction on pulsatile displacement within the optic nerve head (ONH) in primary open-angle glaucoma (POAG) patients with and without axial myopia. Forty-one POAG patients (19 without myopia, 9 with axial myopia and 13 glaucoma with no intervention) participated. Swept-source optical...

The identification of eye diseases and their progression often relies on a clear visualization of the anatomy and on different metrics extracted from Optical Coherence Tomography (OCT) B-scans. However, speckle noise hinders the quality of rapid OCT imaging, hampering the extraction and reliability of biomarkers that require time series. By synchro...

Adoptive T cell therapies rely on the production of T cells with an antigen receptor that directs their specificity toward tumor-specific antigens. Methods for identifying relevant T cell receptor (TCR) sequences, predominantly achieved through the enrichment of antigen-specific T cells, represent a major bottleneck in the production of TCR-enginee...

Objective: To assess the impact of microgravity exposure on ocular rigidity (OR), intraocular pressure (IOP), and ocular pulse amplitude (OPA) following long-term space missions. OR was evaluated using optical coherence tomography (OCT) and deep learning-based choroid segmentation. IOP and OPA were measured with the PASCAL Dynamic Contour Tonometer...

Purpose To evaluate ocular rigidity and choroidal thickness changes in response to microgravity and the Valsalva maneuver in a private astronaut. Methods Ophthalmological examination and Optical Coherence Tomography were performed before, during, and after space flight. Choroidal thickness was measured at all time points at rest and during the Val...

The genetic alterations contributing to migration proficiency, a phenotypic hallmark of metastatic cells required for colonizing distant organs, remain poorly defined. Here, we used single-cell magneto-optical capture (scMOCa) to isolate fast cells from heterogeneous breast cancer cell populations, based on their migratory ability alone. We show th...

Single-cell technologies have become critical tools to understand and characterize the complex dynamics that govern biological systems, from embryonic development to cancer heterogeneity. In this context, identification and capture of live individual cells in heterogenous ensembles typically rely on genetic manipulations that encode fluorescent pro...

Prcis: We provide a free-to-use, open-source algorithm to quantify macular hypotony based on OCT images. This numerical approach calculates a metric that measures the deviations of the Bruch's membrane from a smooth ideal retinal layer. Purpose: Hypotony maculopathy is a recurrent complication of glaucoma surgical interventions, in which extreme...

Objective To develop a non-invasive technique to quantitatively assess the pulsatile deformation due to cardiac contractions of the optic nerve head (ONH). Design Evaluation of a diagnostic test or technology. Participants Healthy subjects with no history of refractive surgery, divided in two cohorts based on their axial length. Methods We prese...

Melanoma is an immunogenic cancer with a high response rate to immune checkpoint inhibitors (ICIs). It harbors a high mutation burden compared with other cancers and, as a result, has abundant tumor-infiltrating lymphocytes (TILs) within its microenvironment. However, understanding the complex interplay between the stroma, tumor cells, and distinct...

Nociceptor Neuron Silencing In article number 2103364, Sebastien Talbot, Christos Boutopoulos, and co‐workers report a nanotechnology‐enabled strategy to silence subsets of unmodified nociceptor neurons. It uses laser stimulation of neurons targeted with gold nanoparticles to heat‐activate TRPV1, turning this channel into a cell‐specific entry port...

Objective Evidence suggests that ocular blood flow dysregulation in vasospastic patients could occur in response to biomechanical stimuli, contributing to optic nerve head susceptibility in glaucoma. We evaluate the role of vasospasticity in the association between ocular rigidity (OR) and neuroretinal damage, hypothesizing that low OR correlates w...

The sensory nervous and immune systems work in concert to preserve homeostasis. While this endogenous interplay protects from danger, it may drive chronic pathologies. Currently, genetic engineering of neurons remains the primary approach to interfere selectively with this potentially deleterious interplay. However, such manipulations are not feasi...

Purpose: Ocular rigidity (OR) is an important biomechanical property, thought to be relevant in the pathophysiology of open-angle glaucoma (OAG). This study aims to evaluate the relationship between OR and neuroretinal damage caused by glaucoma. Methods: One hundred eight subjects (22 with healthy eyes, 23 with suspect discs, and 63 with OAG) were...

Background/aims To evaluate the non-invasive measurement of ocular rigidity (OR), an important biomechanical property of the eye, as a predictor of intraocular pressure (IOP) elevation after anti-vascular endothelial growth factor (anti-VEGF) intravitreal injection (IVI). Methods Subjects requiring IVI of anti-VEGF for a pre-existing retinal condi...

The presence of an immature tumor vascular network contributes to cancer dissemination and the development of resistance to therapies. Strategies to normalize the tumor vasculature are therefore of significant therapeutic interest for cancer treatments. VEGF inhibitors are used clinically to normalize tumor blood vessels. However, the time frame an...

Retinopathy of prematurity (ROP) is the leading cause of blindness in neonates. Inflammation, in particular interleukin-1β (IL-1β), is increased in early stages of the disorder, and contributes to inner and outer retinal vasoobliteration in the oxygen-induced retinopathy (OIR) model of ROP. A small peptide antagonist of IL-1 receptor, composed of t...

Neutrophils represent the immune system’s first line of defense and are rapidly recruited into inflamed tissue. In cancer associated inflammation, phenotypic heterogeneity has been ascribed to this cell type, whereby neutrophils can manifest anti- or pro-metastatic functions depending on the cellular/micro-environmental context. Here, we demonstrat...

USP16 (also known as UBP-M) has emerged as a histone H2AK119 deubiquitylase (DUB) implicated in the regulation of chromatin-associated processes and cell cycle progression. Despite this, available evidence suggests that this DUB is also present in the cytoplasm. How the nucleo-cytoplasmic transport of USP16, and hence its function, is regulated has...

Childhood brain tumors have suspected prenatal origins. To identify vulnerable developmental states, we generated a single-cell transcriptome atlas of >65,000 cells from embryonal pons and forebrain, two major tumor locations. We derived signatures for 191 distinct cell populations and defined the regional cellular diversity and differentiation dyn...

Ocular rigidity (OR) is thought to play a role in the pathogenesis of glaucoma, but the lack of reliable non-invasive measurements has been a major technical challenge. We recently developed a clinical method using optical coherence tomography time-lapse imaging and automated choroidal segmentation to measure the pulsatile choroidal volume change (...

The ability to isolate rare live cells within a heterogeneous population based solely on visual criteria remains technically challenging, due largely to limitations imposed by existing sorting technologies. Here we present a new method that permits labeling cells of interest by attaching streptavidin-coated magnetic beads to their membranes using t...

DNA fiber fluorography is widely employed to study the kinetics of DNA replication, but the usefulness of this approach has been limited by the lack of freely-available automated analysis tools. Quantification of DNA fibers usually relies on manual examination of immunofluorescence microscopy images, which is laborious and prone to inter- and intra...

Multiplexing strategies, which greatly increase the number of simultaneously measured parameters in single experiments, are now being widely implemented by both the pharmaceutical industry and academic researchers. Color has long been used to identify biological signals and, when combined with molecular barcodes, has substantially enhanced the dept...

Mechanisms regulating B cell development, activation, education in the germinal center (GC) and differentiation, underpin the humoral immune response. Protein arginine methyltransferase 5 (Prmt5), which catalyzes most symmetric dimethyl arginine protein modifications, is overexpressed in B cell lymphomas but its function in normal B cells is poorly...

Vision loss caused by retinal diseases affects hundreds of millions of individuals worldwide. The retina is a delicate central nervous system tissue stratified into layers of cells with distinct roles. Currently, there is a void in treatments that selectively target diseased retinal cells and current therapeutic paradigms present complications asso...

Intrinsic and acquired resistance to cisplatin remains a primary hurdle to treatment of high-grade serous ovarian cancer (HGSOC). Cisplatin selectively kills tumor cells by inducing DNA crosslinks that block replicative DNA polymerases. Single-stranded DNA (ssDNA) generated at resulting stalled replication forks (RF) is bound and protected by heter...

Purpose : Gold-nanoparticle (AuNP) mediated femtosecond laser optoporation transiently permeabilizes the cellular membrane, allowing the introduction of membrane-impermeable molecules, such as DNA plasmids, into targeted cells. Maximizing the specificity of AuNP towards target cells is necessary to enhance the safety of the technique for clinical u...

Preclinical studies of vascular retinal diseases rely on the assessment of developmental dystrophies in the oxygen induced retinopathy rodent model. The quantification of vessel tufts and avascular regions is typically computed manually from flat mounted retinas imaged using fluorescent probes that highlight the vascular network. Such manual measur...

Purpose: To perform a pilot study of the neuro-peripapillary retinal tissue deformation during the cardiac cycle among healthy eyes, ocular hypertensive (OHT), open angle glaucoma suspect (OAG-S), and early open angle glaucoma (EOAG) patients using video rate optical coherence tomography (OCT) image series. Methods: OCT line scan sequences of the s...

Neutrophil recruitment guided by chemotactic cues is a central event in host defense against infection and tissue injury. While the mechanisms underlying neutrophil chemotaxis have been extensively studied, these are just recently being addressed by using high-content approaches or surface-bound chemotactic gradients (haptotaxis) in vitro. Here, we...

Ultraviolet (UV) light causes highly genotoxic DNA lesions that are removed by nucleotide excision repair (NER), and NER is critical for preventing UV-associated skin cancers. UV-induced DNA lesions block the progression of DNA polymerases, leading to replicative stress and genomic instability. Upon UV, the ataxia-telangectasia and rad3 related (AT...

The Neuronal ceroid lipofuscinoses (NCLs) are a group of recessive disorders of childhood with overlapping symptoms including vision loss, ataxia, cognitive regression and premature death. 14 different genes have been linked to NCLs (CLN1-CLN14), but the functions of the proteins encoded by the majority of these genes have not been fully elucidated...

Axonal degeneration is a pathophysiological mechanism common to several neurodegenerative diseases. The slow Wallerian degeneration (WldS) mutation, which results in reduced axonal degeneration in the central and peripheral nervous systems, has provided insight into a redox-dependent mechanism by which axons undergo self-destruction. We studied ear...

The use of optical coherence tomography (OCT) to study ocular diseases associated with choroidal physiology is sharply limited by the lack of available automated segmentation tools. Current research largely relies on hand-traced, single B-Scan segmentations because commercially available programs require high quality images, and the existing implem...

Cell Labeling via Photobleaching (CLaP) is an optical technique recently developed to cross-link fluorescent molecules to the surface of individual cells, by focusing a low-power laser on their membrane. Using CLaP, it is possible select single cells or a sub-population based on visual criteria without the need of molecular markers. This technology...

Purpose: Spectral-domain optical coherence tomography (SD-OCT) is widely used in clinical ophthalmology and recently gained popularity in laboratory research involving small rodents. Its noninvasive nature allows repeated measurements, thereby decreasing the number of animals required. However, when used at a conventional dosage, xylazine (an α2-a...

Retinopathy of prematurity (ROP), the most common cause of blindness in premature infants, has long been associated with inner retinal alterations. However, recent studies reveal outer retinal dysfunctions in patients formerly afflicted with ROP. We have recently demonstrated that choroidal involution occurs early in retinopathy. Herein, we investi...

The ability to conduct image-based, non-invasive cell tagging, independent of genetic engineering, is key to cell biology applications. Here we introduce cell labelling via photobleaching (CLaP), a method that enables instant, specific tagging of individual cells based on a wide array of criteria such as shape, behaviour or positional information....

Calnuc is a ubiquitous Ca(2+) -binding protein present on the trans-Golgi network (TGN) and endosomes. However, the precise role of Calnuc in these organelles is poorly characterized. We previously highlighted the role of Calnuc in the transport of LRP9, a new member of a low density lipoprotein (LDL) receptor subfamily that cycles between the TGN...

Optical coherence tomography (OCT) imaging has become a standard diagnostic tool in ophthalmology, providing essential information associated with various eye diseases. In order to investigate the dynamics of the ocular fundus, we present a simple and accurate automated algorithm to segment the inner limiting membrane in video-rate optic nerve head...

Nucleotide excision repair (NER) is a highly-conserved pathway that removes helix-distorting DNA lesions induced by a plethora of mutagens including UV light. Our laboratory previously demonstrated that human cells deficient in either ataxia telangiectasia and rad3-related (ATR) kinase or translesion DNA polymerase η (polη), i.e. key proteins that...

We have developed a novel optical approach to determine pulsatile ocular volume changes using automated segmentation of the choroid, which, together with Dynamic Contour Tonometry (DCT) measurements of intraocular pressure (IOP), allows estimation of the ocular rigidity (OR) coefficient. Spectral Domain Optical Coherence Tomography (OCT) videos wer...

In Saccharomyces cerevisiae, histone H3 lysine 56 acetylation (H3K56Ac) is present in newly synthesized histones deposited throughout the genome during DNA replication. The sirtuins Hst3 and Hst4 deacetylate H3K56 after S-phase, and virtually all histone H3 molecules are K56-acetylated throughout the cell cycle in hst3∆ hst4∆ mutants. Failure to de...

Engineered cell culture substrates are used to study how the spatial and temporal organization of proteins infl uences cellular and molecular processes. These artifi cial microenvironments can be tailored with subcellular resolution to mimic in vitro the distribution of proteins that cells encounter in vivo. Various different methodologies can be u...

Background: The performance of the Single Particle Tracking (SPT) nearest-neighbor algorithm is determined by parameters that need to be set according to the characteristics of the time series under study. Inhomogeneous systems, where these characteristics fluctuate spatially, are poorly tracked when parameters are set globally. Results: We present...

The goal of this study was to assess the effect of corneal hydration on the quality of the femtosecond laser (FSL) anterior lamellar cut. The Visumax FSL was used to dissect an 8-mm-diameter corneal flap in 22 eye bank corneas showing various levels of hydration. The intended ablation depth was 220 µm in all eyes, which corresponded to the maximal...

This chapter presents a simple method to produce substrate-bound protein patterns of micrometer resolution. Our approach uses only low power visible lasers and commercially available reagents to obtain arbitrary patterns of wide concentration range. We provide useful and detailed information on how to assemble the experimental setup to create engin...

Corneal grafts for Descemet's Stripping Automated Endothelial Keratoplasty are commonly prepared using mechanical microkeratomes. However, the cuts produced in such way render corneal lenticules that are thinner centrally than peripherally, thus inducing a hyperopic shift. Here we describe a novel device for preparing donor corneal grafts, in which...