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Low-Cost Clamp-On Photometers (ClampOD) and Tube Photometers (TubeOD) for Online Cell Density Determination.

ABSTRACT: Optical density (OD) measurement is the gold standard to estimate microbial cell density in aqueous systems. Recording microbial growth curves is essential to assess substrate utilization, gauge sensitivity to inhibitors or toxins, or determine the perfect sampling point. Manual sampling for cuvette-photometer-based measurements can cause disturbances and impact growth, especially for strictly anaerobic or thermophilic microbes. For slow growing microbes, manual sampling can cause data gaps that complicate analysis. Online OD measurement systems provide a solution, but are often expensive and ill-suited for applications such as monitoring microbial growth in custom or larger anaerobic vessels. Furthermore, growth measurements of thermophilic cultures are limited by the heat sensitivity of complex electronics. Here, we present two simple, low-cost, self-assembled photometers-a "TubeOD" for online measurement of anaerobic and thermophilic cultures in Hungate tubes and a "ClampOD" that can be attached to virtually any transparent growth vessel. Both OD-meters can be calibrated in minutes. We detail the manufacturing and calibration procedure and demonstrate continuous acquisition of high quality cell density data of a variety of microbes, including strict anaerobes, a thermophile, and gas-utilizing strains in various glassware. When calibrated and operated within their detection limits (ca. 0.3-90% of the photosensor voltage range), these self-build OD-meters can be used for continuous measurement of microbial growth in a variety of applications, thereby, simplifying and enhancing everyday lab operations.

SUBMITTER: Deutzmann JS

PROVIDER: S-EPMC8793360 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:IntroductionThe Aurolab aqueous drainage implant (AADI) is a low-cost glaucoma drainage device that is modelled on the Baerveldt glaucoma implant. Studies on AADI have reported absolute success rates of 41.8-93.1% at 1 year. Most studies report on tube placement in the anterior chamber. We report on results of tube insertion in the sulcus/pars plana.Material and methodsA retrospective chart review of all patients who had undergone AADI implantation (with insertion of tube in the sulcus/posterior segment) between June 2015 and November 2018 was done. Patients were asked to stop anti-glaucoma medications on the 40th post-operative day.ResultsThe mean age was 57.4 ± 13.8 years (n = 30). The mean IOP prior to surgery was 34.4 ± 6.1 mmHg which reduced to 15.4 ± 8.6 mmHg on the 45th post-operative day (p < 0.001). The absolute success at last review was 10% and the qualified success was 80%. The complication rate was 26.7%. Three patients had hypotony related complications noted at/after the 45th day review (none before 40th day). The incidence of ocular motility disturbances was 26.7% though none of the patients reported diplopia. One patient had sideways rotation of the scleral patch graft resulting in tube exposure. This complication was not seen after we shifted to using 9-0 nylon sutures to anchor the graft. Six patients had loss of best corrected visual acuity and one patient developed endophthalmitis. The endophthalmitis was preceded by conjunctival retraction and sloughing off of the scleral patch graft.DiscussionAADI implantation results in a substantial drop in IOP. However, many patients continue to require anti-glaucoma medications. Allowing overlap of scleral/corneal patch graft onto the scleral flap may be effective in preventing peritubular leak. It may be advisable to use 9-0 nylon sutures to secure the scleral patch graft anti-glaucoma medications can be temporarily suspended after the 40th post-operative day to minimize hypotony related complications. Melting of the scleral patch graft may be an early sign of endophthalmitis. It would be prudent to specifically look for ocular motility problems in patients undergoing AADI implantation.

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Low-Cost Clamp-On Photometers (ClampOD) and Tube Photometers (TubeOD) for Online Cell Density Determination.

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