A Case of Sustained Viral Shedding of Mpox With Ocular Involvement Resulting in Vision Loss.

Mpox, caused by infection with Monkeypox virus, usually presents as a mild, self-limited illness in immunocompetent persons that resolves within 2-4 weeks. Serious complications have been reported when mpox lesions involve vulnerable anatomic sites, such as the eye, and in those with substantial immunosuppression. We describe a patient with advanced human immunodeficiency virus infection and sustained viral shedding of mpox with ocular involvement, which resulted in vision loss.

Conjunctival subepithelial fibrosis and meibomian gland atrophy in ocular graft-versus-host disease.

PURPOSE: Dry eye symptoms greatly impact patients' quality of life in ocular graft-versus-host disease (oGVHD). Various ocular surface changes have been reported in oGVHD, including meibomian gland atrophy (MGA) and clinical conjunctival scarring or subepithelial fibrosis (CSEF). The relationships between CSEF, MGA, and other ocular surface changes in oGVHD were examined. METHODS: Charts of 21 consecutive GVHD patients examined by a single ophthalmologist were retrospectively reviewed. International Chronic Ocular Graft-vs-Host-Disease Consensus Group (ICCG) scores were calculated for each patient using previously published methods. The severity of CSEF by slit lamp examination and MGA by infrared meibography were also assessed for each patient. Infrared meibography images were analyzed using ImageJ to determine percent of MGA. Pearson correlation coefficients were calculated using SAS Studio 9.3 (SAS Institute, Cary, NC). RESULTS: In the 42 eyes, no significant correlations were identified among the variables examined (CSEF score, ICCG score, MGA). Further examination revealed asymmetric ocular findings in 20 of 21 patients. Analysis of the more severe eye alone (n = 21) revealed a weakly positive correlation between ICCG score and CSEF (r = 0.54; p = 0.01). No other statistically significant correlations were found. CONCLUSIONS: Clinical CSEF may be an important sign of GVHD impact on the ocular surface and may be relevant in oGVHD severity assessment. Though meibomian glands and conjunctiva are in close proximity, MGA did not correlate with clinical CSEF findings. Some ocular GVHD patients may present with asymmetrical ocular findings, with one eye displaying more severe pathological changes and symptoms despite the systemic nature of GHVD. Further studies are needed to examine these findings.

A Disposable Tear Glucose Biosensor-Part 4: Preliminary Animal Model Study Assessing Efficacy, Safety, and Feasibility.

OBJECTIVE: A prototype tear glucose (TG) sensor was tested in New Zealand white rabbits to assess eye irritation, blood glucose (BG) and TG lag time, and correlation with BG. METHODS: A total of 4 animals were used. Eye irritation was monitored by Lissamine green dye and analyzed using image analysis software. Lag time was correlated with an oral glucose load while recording TG and BG readings. Correlation between TG and BG were plotted against one another to form a correlation diagram, using a Yellow Springs Instrument (YSI) and self-monitoring of blood glucose as the reference measurements. Finally, TG levels were calculated using analytically derived expressions. RESULTS: From repeated testing carried over the course of 12 months, little to no eye irritation was detected. TG fluctuations over time visually appeared to trace the same pattern as BG with an average lag times of 13 minutes. TG levels calculated from the device current measurements ranged from 4 to 20 mg/dL and correlated linearly with BG levels of 75-160 mg/dL (TG = 0.1723 BG = 7.9448 mg/dL; R2 = .7544). CONCLUSION: The first steps were taken toward preliminary development of a sensor for self-monitoring of tear glucose (SMTG). No conjunctival irritation in any of the animals was noted. Lag time between TG and BG was found to be noticeable, but a quantitative modeling to correlate lag time in this study is unnecessary. Measured currents from the sensors and the calculated TG showed promising correlation to BG levels. Previous analytical bench marking showed BG and TG levels consistent with other literature.

A disposable tear glucose biosensor--part 3: assessment of enzymatic specificity.

BACKGROUND: A concept for a tear glucose sensor based on amperometric measurement of enzymatic oxidation of glucose was previously presented, using glucose dehydrogenase flavin adenine dinucleotide (GDH-FAD) as the enzyme. Glucose dehydrogenase flavin adenine dinucleotide is further characterized in this article and evaluated for suitability in glucose-sensing applications in purified tear-like saline, with specific attention to the effect of interfering substances only. These interferents are specifically saccharides that could interact with the enzymatic activity seen in the sensor's performance. METHODS: Bench top amperometric glucose assays were performed using an assay solution of GDH-FAD and ferricyanide redox mediator with samples of glucose, mannose, lactose, maltose, galactose, fructose, sucrose, and xylose at varying concentrations to evaluate specificity, linear dynamic range, signal size, and signal-to-noise ratio. A comparison study was done by substituting an equivalent activity unit concentration of glucose oxidase (GOx) for GDH-FAD. RESULTS: Glucose dehydrogenase flavin adenine dinucleotide was found to be more sensitive than GOx, producing larger oxidation currents than GOx on an identical glucose concentration gradient, and GDH-FAD exhibited larger slope response (-5.65 × 10(-7) versus -3.11 × 10(-7) A/mM), signal-to-noise ratio (18.04 versus 2.62), and linear dynamic range (0-30 versus 0-10 mM), and lower background signal (-7.12 versus -261.63 nA) than GOx under the same assay conditions. GDH-FAD responds equally to glucose and xylose but is otherwise specific for glucose. CONCLUSION: Glucose dehydrogenase flavin adenine dinucleotide compares favorably with GOx in many sensor-relevant attributes and may enable measurement of glucose concentrations both higher and lower than those measurable by GOx. GDH-FAD is a viable enzyme to use in the proposed amperometric tear glucose sensor system and perhaps also in detecting extreme hypoglycemia or hyperglycemia in blood.

Development of a novel single sensor multiplexed marker assay.

There is an increasing desire to measure multiple analytes simultaneously for disease management and detection. However, in the case of invasive devices, it would be better to obtain one small sample and immediately be able to detect the analytes rapidly, as in the case of self-monitoring blood glucose, without the need for additional steps, arrays, or reagents. Electrochemical impedance spectroscopy is used to measure the interaction between ultralow levels of analyte and molecular recognition element in a label-free and rapid manner. Gold nanoparticles were attached to antibodies against interleukin-12 and tumor necrosis factor-α, typical inflammatory markers found with near overlapping responses, on an impedance spectroscopy based biosensor. Cross-reactivity and specificity of tuned antibodies were verified using ELISA. Impedance frequency was quantified by concentration gradients of marker against the device. The natural impedance frequency for interleukin-12 (5.00 Hz) was tuned to a lower frequency four Hertz away from one another for better signal processing. This was accomplished without significantly altering the lower limits of detection (<4 pg ml(-1) and ∼60 pg ml(-1) for interleukin-12 and tumor necrosis factor-α, respectively), no cross-reactivity and specificity as determined by ELISAs. With modeling the nanoscale effects and further development, a larger tuning will be possible for making a better multiplexed sensor. Although interleukin-12 and TNF-α equivalent circuit calculations were modeled here, a sensor with the potential to measure multiple markers at once might offer a solution on the sensor front for simplified management of conditions such as diabetes, where both glucose and hemoglobin A1c values could be obtained.

A disposable tear glucose biosensor-part 1: design and concept testing.

BACKGROUND: Tear glucose has been suggested previously as a potential approach for the noninvasive estimation of blood glucose. While the topic remains unresolved, an overview of previous studies suggests the importance of a tear sampling approach and warrants new technology development. A concept device is presented that meets the needs of a tear glucose biosensor. METHODS: Three approaches to chronoamperometric glucose sensing were evaluated, including glucose oxidase mediated by potassium ferricyanide or oxygen with a hydrogen peroxide catalyst, Prussian blue, and potassium ferricyanide-mediated glucose dehydrogenase. For tear sampling, calcium alginate, poly(2-hydroxyethyl methacrylate), and polyurethane foam were screened as an absorbent tear sampling material. A quantitative model based on the proposed function of concept device was created. RESULTS: For glucose sensing, it was found that potassium ferricyanide with glucose dehydrogenase was ideal, featuring oxygen insensitivity, long-term stability, and a lower limit of detection of 2 muM glucose. Polyurethane foam possessed all of the required characteristics for tear sampling, including reproducible sampling from a hydrogel-simulated, eye surface (4.2 +/- 0.5 microl; n = 8). It is estimated that 100 microM of glucose tear fluid would yield 135 nA (14.9% relative standard deviation). CONCLUSION: A novel concept device for tear glucose sampling was presented, and the key functions of this device were tested and used to model the performance of the final device. Based on these promising initial results, the device is achievable and within reach of current technical capabilities, setting the stage for prototype development.

A disposable tear glucose biosensor-part 2: system integration and model validation.

BACKGROUND: We presented a concept for a tear glucose sensor system in an article by Bishop and colleagues in this issue of Journal of Diabetes Science and Technology. A unique solution to collect tear fluid and measure glucose was developed. Individual components were selected, tested, and optimized, and system error modeling was performed. Further data on prototype testing are now provided. METHODS: An integrated fluidics portion of the prototype was designed, cast, and tested. A sensor was created using screen-printed sensors integrated with a silicone rubber fluidics system and absorbent polyurethane foam. A simulated eye surface was prepared using fluid-saturated poly(2-hydroxyethyl methacrylate) sheets, and the disposable prototype was tested for both reproducibility at 0, 200, and 400 microM glucose (n = 7) and dynamic range of glucose detection from 0 to 1000 microM glucose. RESULTS: From the replicated runs, an established relative standard deviation of 15.8% was calculated at 200 microM and a lower limit of detection was calculated at 43.4 microM. A linear dynamic range was demonstrated from 0 to 1000 microM with an R(2) of 99.56%. The previously developed model predicted a 14.9% variation. This compares to the observed variance of 15.8% measured at 200 microM glucose. CONCLUSION: With the newly designed fluidics component, an integrated tear glucose prototype was assembled and tested. Testing of this integrated prototype demonstrated a satisfactory lower limit of detection for measuring glucose concentration in tears and was reproducible across a physiological sampling range. The next step in the device design process will be initial animal studies to evaluate the current prototype for factors such as eye irritation, ease of use, and correlation with blood glucose.