Browsing by Author "Parekh, Mohit"

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    Next-generation sequencing for the detection of microorganisms present in human donor corneal preservation medium
    (2019-04-01) Parekh, Mohit; Borroni, Davide; Romano, Vito; Kaye, Stephen B.; Camposampiero, Davide; Ponzin, DIego; Ferrari, Stefano
    Objective To detect the presence of microorganisms in the storage media of human donor corneas using next-generation sequencing method. Methods Seven samples from organ culture (OC) group (Cornea Max, Eurobio, Les Ulis, France) with one control (sterile media without any cornea) and seven samples from hypothermic storage group (Cornea Cold, Eurobio) with one control were used for this study. The corneas were placed in the respective storage media for 14 days before collecting the samples. Storage media (2 mL) from each sample were collected in RNAase-free tubes and shipped for ribosomal RNA sequencing of 16 S and 18 S. Simultaneously, another 1 mL of media sample was used for conventional diagnostic method (CDM) using Bactec instruments. Results In both, OC and hypothermic storage and control samples, the most abundant genera were Pseudomonas, Comamonas, Stenotrophomonas, Alcanivorax, Brevundimonas and Nitrobacter. Acidovorax, Acetobacter and Hydrogenophilus were detected mostly in the hypothermic storage group. The most abundant fungal pathogen detected belonged to the genus Malassezia, which was found in both the storage conditions. CDM was negative for microorganisms in all the samples. Conclusion Metagenomics provides full taxonomic profiling of the detected genomic material of the organisms and thus has the potential to deliver a much wider microbiological diagnostic approach than CDM. The costs and turn-around time need to be reduced, and; the detection of viable organisms would help this technology to be introduced into routine clinical practice.
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    Shotgun sequencing to determine corneal infection
    (2020-09) Parekh, Mohit; Romano, Vito; Franch, Antonella; Leon, Pia; Birattari, Federica; Borroni, Davide; Kaye, Stephen B.; Ponzin, Diego; Ahmad, Sajjad; Ferrari, Stefano
    Purpose: To investigate if shotgun-sequencing method could be useful in detailed diagnosis of herpes simplex virus (HSV) infection and compare it with the conventional diagnostic method. Observations: Using a sterile scraper, the infectious part of the ocular surface was scraped gently and placed on a glass slide for conventional diagnosis using PCR and histology and in RNA stabilizing reagent for shotgun sequencing respectively. Concentration of the DNA was determined using a sensitive fluorescence dye-based Qubit dsDNA HS Assay Kit. Shotgun-sequencing libraries were generated using the NEBNext DNA ultra II protocol. The samples were sequenced on the Illumina NextSeq 500 in high output mode with 2X150 bp paired-end sequencing. Taxonomic and functional profiles were generated. Conventional diagnostic method suspected herpetic keratitis. The results indicated presence of an amplified product of 92 bp positive HSV-DNA. Conventional diagnostic method detected the presence of Herpes Simplex Virus DNA (type 1). Shotgun sequencing confirmed the diagnosis of HSV along with the taxonomical profiling of the virus. These results were achieved using 1.9 ng/μL of DNA concentration (114 ng in 60 μL) of the total sample volume. Conclusions and importance: Shotgun sequencing is a hypothesis-free approach that identifies full taxonomic and functional profile of an organism. This technology is advantageous as it requires smaller sample size compared to conventional diagnostic methods.
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    Solar retinopathy : a new setting of red, green, and blue channels
    (2021) Borroni, Davide; Erts, Renars; Vallabh, Neeru A.; Bonzano, Chiara; Sepetiene, Svetlana; Krumina, Zita; Romano, Vito; Parekh, Mohit; Iannetta, Danilo; Rīga Stradiņš University; Department of Biology and Microbiology
    Purpose: To introduce a new color imaging technique using improved settings of red, green, and blue channels for improved delineation of retinal damage in patients with solar retinopathy. Method: A retrospective case series of patients with poor vision secondary to solar retinopathy were analyzed. All patients underwent visual acuity, refraction, and dilated fundus examination. A spectral domain–optical coherence tomography of the macula and color fundus imaging using optimized red, green, and blue color setting was performed. Patients were reviewed over a 6-month period. The data were analyzed for statistical significance using an independent t test and a receiver operating characteristic curve. Results: In total, 20 eyes of 10 patients were included between 2009 and 2017. The mean age was 24.9 ± 18.1 years. Best corrected visual acuity at first consultation was 0.78 ± 0.11 and after 6 months was 0.83 ± 0.09. Spectral domain–optical coherence tomography demonstrated retinal abnormalities at the myoid zone, ellipsoid zone, and the outer segment of photoreceptors. Receiver operating characteristic curve analysis showed an improving effect (area under the curve = 0.62; 95% confidence interval = 0.42–0.79). The color channels parameters, which improve visualization of the lesions were found to be 67-0.98-255 for the R-guided setting, 19-0.63-121 for the B-guided setting, and 7-1.00-129 for the G-guided setting. The ideal red, green, and blue setting was in 24-0.82-229. Conclusion: The use of a new setting of red, green, and blue channels could improve the diagnosis and monitoring of solar retinopathy, hence improving patient care.
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    Tips, Tricks, and Guides in Descemet Membrane Endothelial Keratoplasty Learning Curve
    (2021) Borroni, Davide; Rocha De Lossada, Carlos; Parekh, Mohit; Gadhvi, Kunal; Bonzano, Chiara; Romano, Vito; Levis, Hannah J.; Tzamalis, Aris; Steger, Bernhard; Rechichi, Miguel; Rodriguez-Calvo-De-Mora, Marina; Department of Doctoral Studies
    Lamellar keratoplasty is fast becoming the most popular form of corneal transplantation. The adoption of Descemet membrane endothelial keratoplasty (DMEK) in the management of Fuchs endothelial dystrophy and pseudophakic bullous keratopathy is partly responsible for this shift in the paradigm of management of corneal pathology. The learning curve of DMEK, however, has been proven to be much steeper than previous endothelial keratoplasty procedures. To ease the procedure, experts have proposed multiple innovative techniques from tissue preparation to graft unfolding to aid the more novice surgeon. Here, we collate and share tips and tricks from our collective experiences to support the learning curve and outcomes in DMEK for both the novice and more experienced corneal transplant surgeons.