Effects of Acute Hypocapnia on Postural Standing Balance Measured by Sharpened Romberg Testing (SRT) in Healthy Subjects.

INTRODUCTION: The sharpened Romberg test (SRT) is a physical maneuver that has been used to identify ataxia in individuals in resource-limited settings. Previous research has suggested that performance on balance testing may be affected by hypocapnia. In this study, we sought to determine whether acute hyperventilation-induced hypocapnia affects performance on the SRT at 501 meters above sea level. METHODS: We recruited 22 healthy subjects. Each subject performed a baseline SRT. Subjects were then asked to hyperventilate to the point of hypocapnia, confirmed by measurement with a capnometer. Subjects were then asked to re-perform SRT. The primary endpoint was time to loss of balance, measured as time-to-stepout. RESULTS: Time-to-stepout (TTS) on SRT at baseline had a mean ± standard deviation of 101 ± 117 s. In the hypocapnic condition, TTS was reduced to 48 ± 68 s. TTS normalized to 121 ± 132 s after recovery to normal capnic levels. Time-to-stepout was found to be significantly shorter in the hypocapnic measurement compared to the baseline measurement (P = .0128). Statistical analysis was conducted using one-tailed, paired sample T-tests using a P-value of < .05. CONCLUSIONS: Our study found a statistically and clinically significant reduction in performance on a balance test (SRT) when exposed to acute hyperventilation-induced hypocapnia compared to a eucapnic control. Our results suggest that acute hypocapnia may contribute to neurological dysfunction independently of hypobaric hypoxia.

Relationships between Morning Thirst and Later Hydration Status and Total Water Intake.

Purpose: To investigate the effects of thirst on later hydration status, total water intake (TWI-MA), and its potential sex differences. Methods: Twelve men (mean ± standard deviation; age: 21 ± 2 years; mass: 81.0 ± 15.9 kg) and twelve women (age: 22 ± 3 years; mass: 68.8 ± 15.2 kg) visited the laboratory in the morning (first thing in the morning) and afternoon (2:00-4:00 p.m.) for three consecutive days under a free-living condition. At each visit, urine osmolality (UOSM), urine specific gravity (USG), urine color (UCOL), body mass loss (BML), thirst, and plasma osmolality (POSM) were collected and analyzed. The participants recorded their food and fluid intake between the visits to determine TWI-MA. Linear regression was used to predict the effect of morning thirst on the afternoon hydration indices for all the participants, as well as for males and females separately. Results: Higher morning thirst predicted lower UOSM (r2 = 0.056, p = 0.045), USG (r2 = 0.096, p = 0.008), UCOL (r2 = 0.074, p = 0.021), and higher thirst (r2 = 0.074, p = 0.021) in the afternoon. However, morning thirst did not predict afternoon BML, POSM, or TWI-MA (p > 0.05). In males, higher morning thirst predicted lower afternoon UOSM (r2 = 0.130, p = 0.031) and USG (r2 = 0.153, p = 0.018). Additionally, higher morning thirst predicted higher TWI-MA (r2 = 0.154, p = 0.018) in females. Conclusions: Morning thirst had a negligible impact on later hydration status, specifically with afternoon urine indices. Furthermore, higher thirst sensation did not impact BML, POSM, or TWI-MA. However, thirst sensation minimally contributed to drinking behavior in females. Overall, individuals may not rely solely on thirst sensation to manipulate their drinking behavior to optimize their fluid balance during their daily lives due to the complexity of thirst mechanisms.

Effect of Heat Acclimatization, Heat Acclimation, and Intermittent Heat Training on Maximal Oxygen Uptake.

BACKGROUND: Maximal oxygen uptake (VO2max) is an important determinant of endurance performance. Heat acclimation/acclimatization (HA/HAz) elicits improvements in endurance performance. Upon heat exposure reduction, intermittent heat training (IHT) may alleviate HA/HAz adaptation decay; however, corresponding VO2max responses are unknown. HYPOTHESIS: VO2max is maintained after HAz/HA; IHT mitigates decrements in aerobic power after HAz/HA. STUDY DESIGN: Interventional study. LEVEL OF EVIDENCE: Level 3. METHODS: A total of 27 male endurance runners (mean ± SD; age, 36 ± 12 years; body mass, 73.03 ± 8.97 kg; height, 178.81 ± 6.39 cm) completed VO2max testing at 5 timepoints; baseline, post-HAz, post-HA, and weeks 4 and 8 of IHT (IHT4, IHT8). After baseline testing, participants completed HAz, preceded by 5 days of HA involving exercise to induce hyperthermia for 60 minutes in the heat (ambient temperature, 39.13 ± 1.37°C; relative humidity, 51.08 ± 8.42%). Participants were assigned randomly to 1 of 3 IHT groups: once-weekly, twice-weekly, or no IHT. Differences in VO2max, velocity at VO2max (vVO2), and maximal heart rate (HRmax) at all 5 timepoints were analyzed using repeated-measure analyses of variance with Bonferroni corrections post hoc. RESULTS: No significant VO2max or vVO2 differences were observed between baseline, post-HAz, or post-HA (P = 0.36 and P = 0.09, respectively). No significant group or time effects were identified for VO2max or vVO2 at post-HA, IHT4, and IHT8 (P = 0.67 and P = 0.21, respectively). Significant HRmax differences were observed between baseline and post-HA tests (P < 0.01). No significant group or time HRmax differences shown for post-HA, IHT4, and IHT8 (P = 0.59). CONCLUSION: VO2max was not reduced among endurance runners after HA/HAz and IHT potentially due to participants' similar aerobic training status and high aerobic fitness levels. CLINICAL RELEVANCE: HAz/HA and IHT maintain aerobic power in endurance runners, with HAz/HA procuring reductions in HRmax.

Eccentric muscle-damaging exercise in the heat lowers cellular stress prior to and immediately following future exertional heat exposure.

Muscle-damaging exercise (e.g., downhill running [DHR]) or heat exposure bouts potentially reduce physiological and/or cellular stress during future exertional heat exposure; however, the true extent of their combined preconditioning effects is unknown. Therefore, this study investigated the effect of muscle-damaging exercise in the heat on reducing physiological and cellular stress during future exertional heat exposure. Ten healthy males (mean ± Standard Definition; age, 23 ± 3 years; body mass, 78.7 ± 11.5 kg; height, 176.9 ± 4.7 cm) completed this study. Participants were randomly assigned into two preconditioning groups: (a) DHR in the heat (ambient temperature [Tamb], 35 °C; relative humidity [RH], 40%) and (b) DHR in thermoneutral (Tamb, 20 °C; RH, 20%). Seven days following DHR, participants performed a 45-min flat run in the heat (FlatHEAT [Tamb, 35 °C; RH, 40%]). During exercise, heart rate and rectal temperature (Trec) were recorded at baseline and every 5-min. Peripheral blood mononuclear cells were isolated to assess heat shock protein 72 (Hsp72) concentration between conditions at baseline, immediately post-DHR, and immediately pre-FlatHEAT and post-FlatHEAT. Mean Trec during FlatHEAT between hot (38.23 ± 0.38 °C) and thermoneutral DHR (38.26 ± 0.38 °C) was not significantly different (P = 0.68), with no mean heart rate differences during FlatHEAT between hot (172 ± 15 beats min-1) and thermoneutral conditions (174 ± 8 beats min-1; P = 0.58). Hsp72 concentration change from baseline to immediately pre-FlatHEAT was significantly lower in hot (-51.4%) compared to thermoneutral (+24.2%; P = 0.025) DHR, with Hsp72 change from baseline to immediately post-FlatHEAT also lower in hot (-52.6%) compared to thermoneutral conditions (+26.3%; P = 0.047). A bout of muscle-damaging exercise in the heat reduces cellular stress levels prior to and immediately following future exertional heat exposure.

Satellite-based estimation of total suspended solids and chlorophyll-a concentrations for the Gold Coast Broadwater, Australia.

Satellite retrieval of total suspended solids (TSS) and chlorophyll-a (chl-a) was performed for the Gold Coast Broadwater, a micro-tidal estuarine lagoon draining a highly developed urban catchment area with complex and competing land uses. Due to the different water quality properties of the rivers and creeks draining into the Broadwater, sampling sites were grouped in clusters, with cluster-specific empirical/semi-empirical prediction models developed and validated with a leave-one-out cross validation approach for robustness. For unsampled locations, a weighted-average approach, based on their proximity to sampled sites, was developed. Confidence intervals were also generated, with a bootstrapping approach and visualised through maps. Models yielded varying accuracies (R2 = 0.40-0.75). Results show that, for the most significant poor water quality event in the dataset, caused by summer rainfall events, elevated TSS concentrations originated in the northern rivers, slowly spreading southward. Conversely, high chl-a concentrations were first recorded in the southernmost regions of the Broadwater.

Accelerated annealing of fused filament fabricated (FFF) thermoplastics via an improved core-shell filament.

Thermoplastic parts manufactured via fused filament fabrication (FFF) have limited strength and toughness compared to other types of polymer additive and subtractive manufacturing. Low strength results from poor interlayer adhesion, making FFF parts not suitable for most engineering applications. Post processing solutions, such as annealing, enable healing of these interlayers, thus approaching injection molded parts. Prior work demonstrated a core-shell polycarbonate (PC)-acrylonitrile butadiene styrene (ABS) structured dual material filament to provide thermo-structural stability during annealing of the ABS component; however, annealing was limited to relatively low temperatures (135 °C) and required long annealing times (72 h). In the current work, a PC copolymer with a higher glass transition temperature (173 °C) than conventional PC is processed along with an extrusion-grade ABS into a PC-ABS core-shell filament. This improved dual material filament was printed, annealed, and evaluated via Izod impact testing, ultimately yielding 83% of bulk annealed ABS z-direction strength at an accelerated annealing time (8 h) and higher annealing temperature (155-175 °C). A demonstration part is printed with the dual material filament and annealed at 155 °C for 8 h, resulting in excellent dimensional accuracy, and a ductile failure at 73% higher ultimate load compared to the brittle failure of an as-printed part. This work highlights that material selection and design of a bicomponent filament geometry can lead to parts printed with FFF, with increased strength compared to other post-processing techniques at reduced processing times.

Storing urine samples with moisture preserves urine hydration marker stability up to 21 days.

INTRODUCTION: To assess hydration status, hydration markers [urine color, osmolality, and urine-specific gravity (USG)] are used. Urine color, osmolality, and USG have shown to be stable for 7, 7, and 3 days, respectively, at 4 °C. However, refrigeration could produce a dry environment which enhances evaporation and potentially affects urine hydration markers. PURPOSE: To examine the effect of duration and moisture on urine markers with refrigeration. METHODS: 24 participants provided urine samples between 9 and 10 AM. Urine color, osmolality, and USG were analyzed within 2 h (baseline). Then, each urine sample was divided into two urine cups and placed in a storage container with (moisture condition) and without (no moisture condition) water bath at 3 °C. Hydration markers were analyzed at day 1(D1), D2, D7, D10, D14, and D21. A two-way ANOVA (time x condition) and repeated-measures ANOVA on time were performed to examine differences. RESULTS: No significant (p > 0.05) condition x time effect was observed for urine color (p = 0.363), urine osmolality (p = 0.358), and USG (p = 0.248). When urine samples were stored in moisture condition, urine color (p = 0.126) and osmolality (p = 0.053) were stable until D21, while USG was stable until D2 (p = 0.394). CONCLUSION: When assessing hydration status, it appears that the urine color and osmolality were stable for 21 days, while USG was stable for 2 days when stored with moisture at 3 °C. Our results provide guidelines for practitioners regarding urine storage duration and conditions when urine cannot be analyzed immediately.

Prospective Evaluation of Pain Flares and Time Until Pain Relief Following Musculoskeletal Corticosteroid Injections.

BACKGROUND: Corticosteroid injections are used ubiquitously within musculoskeletal medicine. One of the most common side effects is a postinjection pain flare, though little is known regarding this phenomenon. HYPOTHESIS: Some risk factors are related to postinjection pain flare following an ultrasound-guided corticosteroid injection. STUDY DESIGN: Prospective clinical research study. LEVEL OF EVIDENCE: Level 2. METHODS: Patients undergoing ultrasound-guided corticosteroid injections in an academic orthopaedic and sports medicine clinic were approached to participate. Patients completed a survey immediately following their injection and again 2 weeks later, asking them about their pain and side effects. A postinjection pain flare was defined as an increase in pain, as defined by the patient. RESULTS: A total of 140 patients completed the entirety of the study, with 29 (20.7%) patients reporting a flare of pain. There was a significant effect of younger age on the development of a pain flare after the injection, estimated as 5.5% decreased odds of developing a flare per year of age (P < 0.01). Gender, injection location, body mass index (BMI), preinjection pain, and corticosteroid type had no contributing effect. When patients obtained relief following the corticosteroid injection, 60.4% had improved pain within 3 days, whereas over 93.7% obtained relief within a week. CONCLUSION: Pain flares seem to affect approximately 1 in 5 patients. With increasing age, the likelihood of postinjection pain flare becomes less likely. Sex, injection location, BMI, preinjection pain, and corticosteroid type do not seem to significantly relate to an increase in pain following injection. CLINICAL RELEVANCE: Corticosteroid injections are common procedures in the orthopaedic and sports medicine settings. Younger patients can be counseled on the higher likelihood of a pain flare following a corticosteroid injection.

Baseline water quality of the Gold Coast Broadwater, southern Moreton Bay (Australia).

This study establishes baseline water quality characteristics for the Gold Coast Broadwater, southern Moreton Bay (Australia) utilising routinely monitored parameters between 2016 and 2021, across 18 sites. Combined site mean concentrations of NOx-N, NH3-N and total nitrogen were 11.4 ± 33.4 µg/L, 12.7 ± 27.2 µg/L, and 169 ± 109 µg/L, respectively, whilst PO4-P and total phosphorous were 7.30 ± 5.10 µg/L and 21.7 ± 14.1 µg/L. Additionally, total suspended solids and turbidity combined site means were 6.6 ± 6.0 mg/L and 3.4 ± 2.9 NTU, respectively. During high rainfall periods nutrient concentrations increased by up to >200-, >150-, 15-, 12- and >12-fold for NOx-N, NH3-N, TN, PO4-P and TP, respectively, compared to quiescent conditions. Furthermore, TSS and NTU values increased by up to 15- and 40-fold during periods of measured rainfall compared to quiescent conditions.

Healthcare Economics of a Coronavirus Disease 2019 Pop-Up Vaccination Center.

Introduction: Creation of pop-up vaccination sites at trusted community locations has been encouraged to address vaccine hesitancy and provide equitable access to COVID-19 vaccination in minority communities. This study sought to study the healthcare economics of a community-based COVID-19 pop-up vaccination center in terms of the following: costs associated with operating the vaccination center, analysis of billing data from patients who received the Moderna COVID-19 vaccine, and costs of hospitalization for COVID-19 which may be avoided with widespread vaccination. Methods: The pop-up vaccination center was located in Port Jefferson Station, NY, USA. Costs associated with operation of the COVID-19 pop-up vaccination center were quantified, itemized, and tabulated. Current Procedural Technology codes were used to identify patients who received the Moderna COVID-19 vaccine. Billing data were quantified for the cohort as well as per each patient to receive the vaccine. Costs associated with provision of urgent care, emergency, and hospital services to patients with COVID-19 were obtained. Results: The total cost to operate the vaccination center was $25,880. The vaccination center administered the initial dose of the Moderna COVID-19 vaccine to N=251 patients between March and May, 2021. The standard hospital costs for patients admitted to the medical ICU due to COVID-19 ranged from $8,913 to $190,714, per patient. Conclusion: Since the Moderna COVID-19 vaccine series is effective in preventing hospitalization for 93% of patients, this community-based vaccination center's administration of the vaccine series to 240 patients meant aversion of hospitalization due to COVID-19 related morbidity for 223 patients. Therefore, the true impact of this vaccination center, measured in averted hospital costs, ranges from $1,987,599 to $42,529,222.

A waterfall of susceptibility results: impact of microbiology testing cascade for MDROs.

Cascade reporting is an antimicrobial stewardship strategy which selectively reports broad-spectrum antibiotic susceptibility when narrower-spectrum agents are resistant. Three regional laboratories, which provide microbiology services for HCA Healthcare hospitals in Florida, implemented a standardized antibiotic testing cascade for multi-drug resistant organisms. This study evaluated the impact of the testing cascade on time to susceptibility results for carbapenem-resistant Gram-negative organisms. Appropriateness of manual susceptibility test selection was also assessed. Compliance with the testing cascade was 56%. Appropriateness of manual tests in the pre- and post-intervention groups was 87% (257/297) and 96% (310/323), respectively (P < 0.0001). Median time to first manual test result was 23.1 hours (IQR: 19.8-25.2 hours) in the pre-intervention group and 23.9 hours (IQR: 20.2-27.0 hours) in the post-intervention group (P = 0.11). Implementation of a testing cascade did not result in faster manual susceptibility results, however there was a significant increase in testing appropriateness.

Efficacy and safety of reslizumab in the treatment of eosinophilic granulomatosis with polyangiitis.

BACKGROUND: Eosinophilic granulomatosis with polyangiitis (EGPA), a rare vasculitis with substantial morbidity, is characterized by asthma, eosinophilia, sinusitis, pulmonary infiltrates, neuropathy, positivity for antineutrophil cytoplasmic antibody, and multiorgan vasculitis. Although treatment options previously included corticosteroids and immunosuppressants, anti-interleukin 5 therapies have gained interest in EGPA treatment. Mepolizumab was approved for and recently benralizumab was found to have safety and efficacy in EGPA. OBJECTIVE: To determine the safety and efficacy of reslizumab in EGPA. METHODS: In this open-label, pilot study, we evaluated the safety and efficacy of intravenous reslizumab (3 mg/kg) in EGPA in 10 subjects. Oral corticosteroid dose, adverse events, exacerbations, symptom control, disease activity, blood markers, and lung function were evaluated before, during, and after 7 monthly reslizumab treatments. RESULTS: Reslizumab was tolerated and resulted in a significant reduction in daily oral corticosteroid (P < .05). Of the 10 subjects, 3 experienced an EGPA exacerbation during the treatment. One had a severe adverse event, requiring removal from the study. CONCLUSION: Yielding similar results to other anti-interleukin 5 biologic medications, reslizumab is generally a safe and effective treatment for EGPA that warrants further study. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT02947945.

Benralizumab as a Steroid-Sparing Treatment Option in Eosinophilic Granulomatosis with Polyangiitis.

BACKGROUND: Eosinophilic granulomatosis with polyangiitis (EGPA) is a vasculitis associated with significant morbidity and mortality that has historically been treated with systemic corticosteroids and immunosuppressants. The IL-5 antagonist mepolizumab was Food and Drug Administration approved in 2017 after demonstrating safety and efficacy in EGPA. We hypothesized that benralizumab, an IL-5 receptor antagonist approved for eosinophilic asthma, would demonstrate safety and efficacy in EGPA. OBJECTIVES: To determine the safety and efficacy of benralizumab in EGPA as measured by reduction in oral corticosteroid dose and EGPA exacerbations. METHODS: We conducted a prospective 40-week open-label pilot study of benralizumab 30 mg administered subcutaneously in 10 patients with EGPA. Adverse events, oral corticosteroid dosing, exacerbations, and lung function were evaluated before, during, and after benralizumab treatment. Paired tests and tests derived from longitudinal models were used to compare outcome variables between phases or visits. RESULTS: Benralizumab was well tolerated and resulted in reduction of median corticosteroid dose from 15 mg at the start to 2 mg at the end of treatment. Geometric mean corticosteroid dose was reduced from 11.6 mg during pretreatment to 6.3 mg during treatment phase. Five patients were able to achieve a dose of 0 mg. Mean annualized exacerbation rate was lowest during the treatment (1.5) compared with the pre- and posttreatment phases (4.6, P = .008 for treatment vs pre- and postphases combined). CONCLUSIONS: Benralizumab was well tolerated, facilitated oral corticosteroid reduction, and reduced exacerbations in EGPA. Larger controlled trials are warranted to further evaluate the role of benralizumab in EGPA.

Supplemental CO2 improves oxygen saturation, oxygen tension, and cerebral oxygenation in acutely hypoxic healthy subjects.

Oxygen is viewed in medicine as the sole determinant of tissue oxygenation, though carbon dioxide homeostasis is equally important and clinically often ignored. The aims of this study were as follows: (a) to examine the effects of different acute hypoxic conditions on partial pressure of arterial oxygen ( PaO2 ), arterial oxygen saturation of hemoglobin ( SaO2 ), and regional cerebral saturation of hemoglobin (rSO2 ); and (b) to evaluate supplemental CO2 as a tool to improve oxygenation in acutely hypoxic individuals. We hypothesized that exposure to gas mixtures with added CO2 would improve oxygenation in hypoxic human subjects. Twenty healthy subjects were exposed to 5-min intervals of two gas mixtures: hypoxic gas mixture containing 8% oxygen, and a CO2 -enriched mixture containing 8% oxygen plus either 3% or 5% CO2 . Ten subjects received the 3% CO2 -enriched mixture, and the remaining 10 subjects received the 5% CO2 -enriched mixture. The order of exposure was randomized. Blood gases, pulse oximetry, end-tidal CO2 , and cerebral oximetry were measured. Compared to the purely hypoxic gas group, PaO2 was increased in the 3% and 5% CO2 -enriched groups by 14.9 and 9.5 mmHg, respectively. Compared to pure hypoxia, SaO2 was increased in the 3% and 5% CO2 -enriched groups by 16.8% and 12.9%, respectively. Both CO2 -enriched gas groups had significantly higher end-exposure rSO2 and recovered to baseline rSO2 within 1 min, compared to the pure hypoxic gas group, which returned to baseline in 5 min. These results suggest that in acutely hypoxic subjects, CO2 supplementation improves blood oxygen saturation and oxygen tension as well as cerebral oxygenation measures.

Vancomycin volume of distribution estimation in adults with class III obesity.

PURPOSE: To compare methods of estimating vancomycin volume of distribution (V) in adults with class III obesity. METHODS: A retrospective, multicenter pharmacokinetic analysis of adults treated with vancomycin and monitored through measurement of peak and trough concentrations was performed. Individual pharmacokinetic parameter estimates were obtained via maximum a posteriori Bayesian analysis. The relationship between V and body weight was assessed using linear regression. Mean bias and root-mean-square error (RMSE) were calculated to assess the precision of multiple methods of estimating V. RESULTS: Of 241 patients included in the study sample, 159 (66.0%) had a body mass index (BMI) of 40.0-49.9 kg/m2, and 82 (34.0%) had a BMI of ≥50.0 kg/m2. The median (5th, 95th percentile) weight of patients was 136 (103, 204) kg, and baseline characteristics were similar between BMI groups. The mean ± S.D. V was lower in patients with a BMI of 40.0-49.9 kg/m2 than in those with a BMI of ≥50.0 kg/m2 (72.4 ± 19.6 L versus 79.3 ± 20.6 L, p = 0.009); however, body size poorly predicted V in regression analyses (R2 < 0.20). A fixed estimate of V (75 L) and use of a weight-based value (0.52 L/kg by total body weight [TBW]) yielded similar bias and error in this population. CONCLUSION: Results of the largest analysis of vancomycin V in class III obesity to date indicated that use of a fixed V value (75 L) and use of a TBW-based estimate (0.52 L/kg) for estimation of vancomycin V in patients with a BMI of ≥40.0 kg/m2 have similar bias. Two postdistribution vancomycin concentrations are needed to accurately determine patient-specific pharmacokinetic parameters, estimate area under the curve, and improve the precision of vancomycin dosing in this patient population.

Clinical management of rib fractures and methods for prevention of pulmonary complications: A review.

Rib fractures are common injuries associated with significant morbidity and mortality, largely due to pulmonary complications. Despite equivocal effectiveness data, incentive spirometers are widely utilized to reduce pulmonary complications in the postoperative setting. Few studies have evaluated the effectiveness of incentive spirometry after rib fracture. Multiple investigations have demonstrated incentive spirometry to be an important screening tool to identify high-risk rib fracture patients who could benefit from aggressive, multidisciplinary pulmonary complication prevention strategies. This review evaluates the epidemiology of rib fractures, their associated pulmonary complications, along with the evidence for optimizing their clinical management through the use of incentive spirometry, multimodal analgesia, and surgical fixation.

Retinal Deficits Precede Cognitive and Motor Deficits in a Rat Model of Type II Diabetes.

Purpose: To investigate the temporal appearance of retinal, cognitive, and motor deficits in Goto-Kakizaki (GK) rats, a spontaneously occurring, polygenic model of type II diabetes. GK rats develop impaired insulin secretion at 2 weeks and fasting hyperglycemia at 4 weeks. Methods: In male and female GK rats and Wistar controls, glucose tolerance test (hyperglycemia) and electroretinogram (ERG, retinal function) were performed at 4 and 8 weeks of age. Spectral domain-optical coherence tomography (retinal structure) was assessed at 6 weeks. Spatial alternation (cognitive function) and number of entries (exploratory behavior) were assessed via Y-maze at 4, 5, 6, 7, and 8 weeks. Rotarod (motor function) was performed at 4, 6, and 8 weeks. Results: By 4 weeks, the GK rats exhibited significant glucose intolerance (P < 0.001) and retinal deficits, including delays in ERG implicit times (flicker, P < 0.01; oscillatory potentials, P < 0.001). In addition, the GK rats showed greater ERG amplitudes (P < 0.001) and thinner retinas (P < 0.001). At 7 weeks, the GK rats showed deficits in cognitive function (P < 0.001) and exploratory behavior (P < 0.01). However, no motor function deficits were observed by 8 weeks. Interestingly, the male GK rats showed greater hyperglycemia (P < 0.05), but the female rats showed greater ERG delays (P < 0.001). Conclusions: In GK rats, retinal function deficits developed prior to cognitive or motor deficits. Future studies will investigate common mechanistic links, long-term functional and vascular changes, and whether early retinal deficits can predict cognitive dysfunction or late-stage retinal disease.