Association between intraprocedural drops in blood pressure and infarct growth rate patterns after acute large-vessel occlusions.

BACKGROUND: Infarct growth rate (IGR) differs among patients with acute ischemic stroke due to large vessel occlusion (LVO-AIS), and this variability has critical clinical repercussions. We explored IGR patterns and their association with blood pressure during endovascular therapy (EVT). METHODS: This is a two-center cohort observational study that included consecutive anterior circulation LVO-AIS patients who underwent EVT and achieved modified Thrombolysis in Cerebral Infarction (mTICI) 2 c-3. Initial and final infarct volumes (FIV) were defined using admission computed tomography perfusion (CTP) defined as relative cerebral blood flow (rCBF) <30%, and diffusion-weighted imaging-magnetic resonance imaging (DWI-MRI) at 24 hours post-EVT. We categorized IGR patterns as exponential (ExpIGR) and Non-exponential (NonExp) based on their growth curves. We then dichotomized ExpIGR clinical significance based on the association of infarct growth with 90-day Modified Rankin Score (mRS) as ExpIGR-A (>13 mL) and ExpIGR-B (<13 mL). Intraprocedural blood pressure (BP) drops were calculated as the difference between median arterial pressure (MAP) at admission and the lowest intraprocedural MAP reading before recanalization, and the area between admission MAP threshold and all lower measurements of intraprocedural MAP. Logistic and linear regression were used to investigate associations between variables of interest. RESULTS: Of 159 modified Thrombolysis in Cerebral Infarction (mTICI) 2 c-3 patients, we found that 36% demonstrated ExpIGR-A, 31% ExpIGR-B, and 32.7% NonExp patterns. The Exp-A and Exp-B groups differed significantly in National Institutes of Health Stroke Scale (NIHSS) score, Alberta Stroke Program Early CT Score (ASPECTS), glucose, and FIV. The Exp-A and NonExp groups differed in rCBF <30% vol, and time of stroke onset (SO) to admission CTP; and the Exp-B and NonExp groups in NIHSS, rCBF <30%, Tmax <6 s volume, collateral flow measured by hypoperfusion intensity ratio (HIR), and FIV. Hypotensive MAP area (HMA) was independently associated with an ExpIGR-A pattern. Infarct volume increased by 1 mL per 100 units of hypotensive area and 4.2 mL per 0.1 units of HIR, with a significant interaction between both variables. CONCLUSION: After an LVO-AIS, the IGR can be differentiated into two distinct exponential and non-exponential patterns. A subgroup of patients with the exponential pattern experienced clinically meaningful infarct growth rates between CTP acquisition and reperfusion and seem to be highly vulnerable to episodes of sustained intraprocedural BP drops during EVT.

A Comprehensive Approach to Sample Preparation for Electron Microscopy and the Assessment of Mitochondrial Morphology in Tissue and Cultured Cells.

Mitochondria respond to metabolic demands of the cell and to incremental damage, in part, through dynamic structural changes that include fission (fragmentation), fusion (merging of distinct mitochondria), autophagic degradation (mitophagy), and biogenic interactions with the endoplasmic reticulum (ER). High resolution study of mitochondrial structural and functional relationships requires rapid preservation of specimens to reduce technical artifacts coupled with quantitative assessment of mitochondrial architecture. A practical approach for assessing mitochondrial fine structure using two dimensional and three dimensional high-resolution electron microscopy is presented, and a systematic approach to measure mitochondrial architecture, including volume, length, hyperbranching, cristae morphology, and the number and extent of interaction with the ER is described. These methods are used to assess mitochondrial architecture in cells and tissue with high energy demand, including skeletal muscle cells, mouse brain tissue, and Drosophila muscles. The accuracy of assessment is validated in cells and tissue with deletion of genes involved in mitochondrial dynamics.

Functional and Safety Outcomes of Carotid Artery Stenting and Mechanical Thrombectomy for Large Vessel Occlusion Ischemic Stroke With Tandem Lesions.

Importance: Approximately 10% to 20% of large vessel occlusion (LVO) strokes involve tandem lesions (TLs), defined as concomitant intracranial LVO and stenosis or occlusion of the cervical internal carotid artery. Mechanical thrombectomy (MT) may benefit patients with TLs; however, optimal management and procedural strategy of the cervical lesion remain unclear. Objective: To evaluate the association of carotid artery stenting (CAS) vs no stenting and medical management with functional and safety outcomes among patients with TL-LVOs. Design, Setting, and Participants: This cross-sectional study included consecutive patients with acute anterior circulation TLs admitted across 17 stroke centers in the US and Spain between January 1, 2015, and December 31, 2020. Data analysis was performed from August 2021 to February 2022. Inclusion criteria were age of 18 years or older, endovascular therapy for intracranial occlusion, and presence of extracranial internal carotid artery stenosis (>50%) demonstrated on pre-MT computed tomography angiography, magnetic resonance angiography, or digital subtraction angiography. Exposures: Patients with TLs were divided into CAS vs nonstenting groups. Main Outcomes and Measures: Primary clinical and safety outcomes were 90-day functional independence measured by a modified Rankin Scale (mRS) score of 0 to 2 and symptomatic intracranial hemorrhage (sICH), respectively. Secondary outcomes were successful reperfusion (modified Thrombolysis in Cerebral Infarction score ≥2b), discharge mRS score, ordinal mRS score, and mortality at 90 days. Results: Of 685 patients, 623 (mean [SD] age, 67 [12.2] years; 406 [65.2%] male) were included in the analysis, of whom 363 (58.4%) were in the CAS group and 260 (41.6%) were in the nonstenting group. The CAS group had a lower proportion of patients with atrial fibrillation (38 [10.6%] vs 49 [19.2%], P = .002), a higher proportion of preprocedural degree of cervical stenosis on digital subtraction angiography (90%-99%: 107 [32.2%] vs 42 [20.5%], P < .001) and atherosclerotic disease (296 [82.0%] vs 194 [74.6%], P = .003), a lower median (IQR) National Institutes of Health Stroke Scale score (15 [10-19] vs 17 [13-21], P < .001), and similar rates of intravenous thrombolysis and stroke time metrics when compared with the nonstenting group. After adjustment for confounders, the odds of favorable functional outcome (adjusted odds ratio [aOR], 1.67; 95% CI, 1.20-2.40; P = .007), favorable shift in mRS scores (aOR, 1.46; 95% CI, 1.02-2.10; P = .04), and successful reperfusion (aOR, 1.70; 95% CI, 1.02-3.60; P = .002) were significantly higher for the CAS group compared with the nonstenting group. Both groups had similar odds of sICH (aOR, 0.90; 95% CI, 0.46-2.40; P = .87) and 90-day mortality (aOR, 0.78; 95% CI, 0.50-1.20; P = .27). No heterogeneity was noted for 90-day functional outcome and sICH in prespecified subgroups. Conclusions and Relevance: In this multicenter, international cross-sectional study, CAS of the cervical lesion during MT was associated with improvement in functional outcomes and reperfusion rates without an increased risk of sICH and mortality in patients with TLs.

Hyperacute immune responses associate with immediate neuropathology and motor dysfunction in large vessel occlusions.

OBJECTIVE: Despite successful endovascular therapy, a proportion of stroke patients exhibit long-term functional decline, regardless of the cortical reperfusion. Our objective was to evaluate the early activation of the adaptive immune response and its impact on neurological recovery in patients with large vessel occlusion (LVO). METHODS: Nineteen (13 females, 6 males) patients with acute LVO were enrolled in a single-arm prospective cohort study. During endovascular therapy (EVT), blood samples were collected from pre and post-occlusion, distal femoral artery, and median cubital vein (controls). Cytokines, chemokines, cellular and functional profiles were evaluated with immediate and follow-up clinical and radiographic parameters, including cognitive performance and functional recovery. RESULTS: In the hyperacute phase (within hours), adaptive immune activation was observed in the post-occlusion intra-arterial environment (post). Ischemic vascular tissue had a significant increase in T-cell-related cytokines, including IFN-γ and MMP-9, while GM-CSF, IL-17, TNF-α, IL-6, MIP-1a, and MIP-1b were decreased. Cellularity analysis revealed an increase in inflammatory IL-17+ and GM-CSF+ helper T-cells, while natural killer (NK), monocytes and B-cells were decreased. A correlation was observed between hypoperfused tissue, infarct volume, inflammatory helper, and cytotoxic T-cells. Moreover, helper and cytotoxic T-cells were also significantly increased in patients with improved motor function at 3 months. INTERPRETATION: We provide evidence of the activation of the inflammatory adaptive immune response during the hyperacute phase and the association of pro-inflammatory cytokines with greater ischemic tissue and worsening recovery after successful reperfusion. Further characterization of these immune pathways is warranted to test selective immunomodulators during the early stages of stroke rehabilitation.

Direct to angiosuite strategy versus standard workflow triage for endovascular therapy: systematic review and meta-analysis.

BACKGROUND: Reducing stroke workflow times when performing endovascular thrombectomy is associated with improvement in clinical outcomes. We compared outcomes among large vessel occlusion (LVO) stroke patients following the direct to angiosuite (DTAS) strategy versus standard workflow (SW) when undergoing endovascular therapy. METHODS: We conducted a systematic review and meta-analysis to compare rates of functional outcomes, reperfusion, symptomatic intracranial hemorrhage (sICH) and stroke workflow metrics. We included observational studies and clinical trials that compared the DTAS strategy versus SW, and at least one outcome of interest was assessed. Clinical, methodological and statistical heterogeneity were measured, and a random-effects model was used. RESULTS: 12 studies were included in the systematic review and 8 in the meta-analysis (n=2890). The DTAS strategy was associated with significant higher odds of good functional outcome at 90 days (47.3% vs 34.9%; OR 1.58, 95% CI 1.16 to 2.14) and a significant average reduction of door-to-puncture (mean differences (MD) -35.09, 95% CI -49.76 to -20.41) and door-to-reperfusion times (MD -32.88, 95% CI -50.75 to -15.01). We found no differences in sICH (OR 0.80, 95% CI 0.53 to 1.20), mortality (OR 1.00, 95% CI 0.60 to 1.67) or successful reperfusion rates (OR 1.37, 95% CI 0.82 to 2.29). Moreover, the DTAS strategy was associated with greater odds of dramatic clinical improvement at 24 hours (OR 1.79, 95% CI 1.15 to 2.79). CONCLUSION: Patients undergoing the DTAS strategy had a significant reduction in door-to-puncture and door-to-reperfusion times. This resulted in an increased rate of early neurological and 90-day functional recovery without compromising safety in LVO patients undergoing endovascular thrombectomy.

Safety and efficacy of the surpass streamline for intracranial aneurysms (SESSIA): A multi-center US experience pooled analysis.

BACKGROUND AND PURPOSE: Flow diversion has established as standard treatment for intracranial aneurysms, the Surpass Streamline is the only FDA-approved braided cobalt/chromium alloy implant with 72-96 wires. We aimed to determine the safety and efficacy of the Surpass in a post-marketing large United States cohort. MATERIALS AND METHODS: This is a retrospective multicenter study of consecutive patients treated with the Surpass for intracranial aneurysms between 2018 and 2021. Baseline demographics, comorbidities, and aneurysm characteristics were collected. Efficacy endpoint included aneurysm occlusion on radiographic follow-up. Safety endpoints were major ipsilateral ischemic stroke or treatment-related death. RESULTS: A total of 277 patients with 314 aneurysms were included. Median age was 60 years, 202 (73%) patients were females. Hypertension was the most common comorbidity in 156 (56%) patients. The most common location of the aneurysms was the anterior circulation in 89% (279/314). Mean aneurysm dome width was 5.77 ± 4.75 mm, neck width was 4.22 ± 3.83 mm, and dome/neck ratio was 1.63 ± 1.26. Small-sized aneurysms were 185 (59%). Single device was used in 94% of the patients, mean number of devices per patient was 1.06. At final follow-up, complete obliteration rate was 81% (194/239). Major stroke and death were encountered in 7 (3%) and 6 (2%) cases, respectively. CONCLUSION: This is the largest cohort study using a 72-96 wire flow diverter. The Surpass Streamline demonstrated a favorable safety and efficacy profile, making it a valuable option for treating not only large but also wide-necked small and medium-sized intracranial aneurysms.

Acute Carotid Artery Stenting Versus Balloon Angioplasty for Tandem Occlusions: A Systematic Review and Meta-Analysis.

Background Despite thrombectomy having become the standard of care for large-vessel occlusion strokes, acute endovascular management in tandem occlusions, especially of the cervical internal carotid artery lesion, remains uncertain. We aimed to compare efficacy and safety of acute carotid artery stenting to balloon angioplasty alone on treating the cervical lesion in tandem occlusions. Similarly, we aimed to explore those outcomes' associations with technique approaches and use of thrombolysis. Methods and Results We performed a systematic review and meta-analysis to compare functional outcomes (modified Rankin Scale), reperfusion, and symptomatic intracranial hemorrhage and 3-month mortality. We explored the association of first approach (anterograde/retrograde) and use of thrombolysis with those outcomes as well. Two independent reviewers performed the screening, data extraction, and quality assessment. A random-effects model was used for analysis. Thirty-four studies were included in our systematic review and 9 in the meta-analysis. Acute carotid artery stenting was associated with higher odds of modified Rankin Scale score ≤2 (odds ratio [OR], 1.95 [95% CI, 1.24-3.05]) and successful reperfusion (OR, 1.89 [95% CI, 1.26-2.83]), with no differences in mortality or symptomatic intracranial hemorrhage rates. Moreover, a retrograde approach was significantly associated with modified Rankin Scale score ≤2 (OR, 1.72 [95% CI, 1.05-2.83]), and no differences were found on thrombolysis status. Conclusions Carotid artery stenting and a retrograde approach had higher odds of successful reperfusion and good functional outcomes at 3 months than balloon angioplasty and an anterograde approach, respectively, in patients with tandem occlusions. A randomized controlled trial comparing these techniques with structured antithrombotic regimens and safety outcomes will offer definitive guidance in the optimal management of this complex disease.

Probabilistic Pairwise Model Comparisons Based on Bootstrap Estimators of the Kullback-Leibler Discrepancy.

When choosing between two candidate models, classical hypothesis testing presents two main limitations: first, the models being tested have to be nested, and second, one of the candidate models must subsume the structure of the true data-generating model. Discrepancy measures have been used as an alternative method to select models without the need to rely upon the aforementioned assumptions. In this paper, we utilize a bootstrap approximation of the Kullback-Leibler discrepancy (BD) to estimate the probability that the fitted null model is closer to the underlying generating model than the fitted alternative model. We propose correcting for the bias of the BD estimator either by adding a bootstrap-based correction or by adding the number of parameters in the candidate model. We exemplify the effect of these corrections on the estimator of the discrepancy probability and explore their behavior in different model comparison settings.

Optimal Woven EndoBridge (WEB) Device Size Selection Using Automated Volumetric Software.

INTRODUCTION: Selecting the appropriate Woven EndoBridge (WEB) device sizing for the treatment of wide-neck bifurcation aneurysms (WNBAs) remains challenging. The aim of this study was to evaluate different volumetric-based imaging methodologies to predict an accurate WEB device size selection to result in a successful implantation. METHODS: All consecutive patients treated with WEB devices for intracranial aneurysms from January 2019 to June 2020 were included. Aneurysm dimensions to calculate aneurysm volumes were measured using three different modalities: automated three-dimensional (3D) digital subtraction angiography (DSA), manual 3D DSA, and two-dimensional (2D) DSA. The device-aneurysm volume (DAV) ratio was defined as device volume divided by the aneurysm volume. WEB volumes and the DAV ratios were used for assessing the device implantation success and follow-up angiographic outcomes at six months. Pearson correlation, Wilcoxon Rank Sum test, and density approximations were used for estimating the WEB volumes and the imaging modality volumes for successful implantation. RESULTS: A total of 41 patients with 43 aneurysms were included in the study. WEB device and aneurysm volume correlation coefficient was highest for 3D automatic (r = 0.943), followed by 3D manual (r = 0.919), and 2D DSA (r = 0.882) measurements. Measured median volumes were significantly different for 3D automatic and 2D DSA (p = 0.017). The highest rate of successful implantation (87.5%) was between 0.6 and 0.8 DAV ratio. CONCLUSION: Pre-procedural assessment of DAV ratios may increase WEB device implantation success. Our results suggest that volumetric measurements, especially using automated 3D volumes of the aneurysms, can assist in accurate WEB device size selection.

Safety and Feasibility of Symptomatic Carotid Artery Stent-Assisted Revascularization within 48 Hours after Symptoms Onset.

OBJECTIVE: We aimed to evaluate the safety and feasibility of carotid artery stenting (CAS) performed in the hyperacute period. METHODS: We analyzed a retrospective database of CAS patients from our center. We included patients with symptomatic isolated ipsilateral extracranial carotid stenosis and acute tandem occlusions who underwent CAS. Hyperacute CAS (HCAS) and acute CAS (ACAS) groups were defined as CAS within 48 hours and >48 hours to 14 days from symptoms onset, respectively. The primary outcome was a composite of any stroke, myocardial infarction, or death at 3 months of follow-up. Secondary outcomes were periprocedural complications and restenosis or occlusion rates. RESULTS: We included 97 patients, 39 with HCAS and 58 with ACAS. There was no significant difference between groups for the primary outcome (HCAS 3.3% vs. ACAS 6.1%; p = 1). There were no differences in the rate of perioperative complications between groups although a trend was observed (HCAS 15.3% vs. ACAS 3.4%; p = .057). The rate of restenosis or occlusion between groups (HCAS 8.1% vs. ACAS 9,1%; log-rank test p = .8) was similar with a median time of follow-up of 13.7 months. CONCLUSION: Based on this study, CAS may be feasible in the hyperacute period. However, there are potential higher rates of perioperative complications in the hyperacute group, primarily occurring in MT patients with acute tandem occlusion. A larger multicenter study may be needed to further corroborate our findings.

Quantitative Assessment of Hyperdense Sign Measured by Hounsfield Units is Associated with Unsuccessful Mechanical Thrombectomy.

PURPOSE: Despite advancement in mechanical thrombectomy (MT) techniques, 10-30% of MT for large vessel occlusions (LVO) are unsuccessful. Current prediction models fail to address the association between patient-specific factors and reperfusion. We aimed to evaluate objective, easily reproducible, admission clinical and radiological biomarkers that predict unsuccessful MT. METHODS: We analyzed consecutive anterior LVO MT patients at two comprehensive stroke centers. The primary outcome was unsuccessful reperfusion defined by a modified thrombolysis in cerebral infarction (mTICI) score of 0-2a. We quantitatively assessed the hyperdense vessel sign by measuring Hounsfield units (HU) on admission computed tomography (CT). Receiver operating characteristic (ROC) curves were plotted to estimate the predictive value of quantitative hyperdense middle cerebral artery (MCA) measurements (delta and ratio) and of the final model for mTICI scores. We performed multivariable logistic regression to analyze associations with outcomes. RESULTS: Out of 348 patients 87 had unsuccessful MT. Smoking, difficult arch, vessel tortuosity, vessel calcification, diminutive vessels, truncal M1 occlusion, delta HU and HU ratio were significantly associated with unsuccessful MT in the univariate analysis. When we fitted two separate multivariate models including all significant variables and a HU measurement; delta HU <6 (odds ratio, OR = 2.07, 95% confidence intervals, CI 1.09-3.92) and HU ratio ≤1.1 (OR = 2.003, 95% CI 1.05-3.81) were independently associated with failed MT after adjustment for smoking, diminutive vessels, vessel tortuosity, and difficult arch. The area under the curve AUC<9 of the final model was 0.717. CONCLUSION: Novel radiological biomarkers on CT, CT angiography (CTA) and digital subtraction angiography (DSA) may help identify patients refractory to standard MT and prepare interventionalists for using additional alternative methods. Quantitative assessment of HU (delta and ratio) may be important in developing objective prediction tools for unsuccessful MT.

Safety and efficacy of symptomatic carotid artery stenting performed in an emergency setting.

INTRODUCTION: Carotid artery stenting (CAS) has increasingly emerged as an alternative strategy to carotid endarterectomy in the treatment of patients with symptomatic carotid stenosis. Optimal timing for CAS after symptoms onset remains unclear. We aimed to evaluate the safety and efficacy of CAS when performed in an emergency setting. PATIENTS AND METHODS: We performed a retrospective analysis of CAS patients admitted to our CSC with symptomatic extracranial carotid occlusion or significant stenosis from January 2014-September 2019. Emergency CAS was defined as CAS performed during the same hospitalization from TIA/stroke onset, whereas elective CAS as CAS performed on a subsequent admission. The primary outcome was defined as the occurrence of any stroke, myocardial infarction, or death related to the procedure at 3 months of follow-up. Secondary outcomes included periprocedural complications and the rate of restenosis/occlusion at follow-up. Logistic regression and survival analyses were used to compare outcomes and restenosis at follow-up. RESULTS: We identified 75 emergency and 104 elective CAS patients. Emergency CAS patients had significantly higher rates of ipsilateral carotid occlusion (17% vs. 2%, p < 0.001) and use of general anesthesia (19% vs. 4%, p = 0.001) than elective CAS. There were no significant differences between emergency and elective CAS in the primary (5.7% vs. 1%, p = 0.161) and secondary (9% vs. 4.8%, p = 0.232) outcomes. We did not find differences in the rate of restenosis/occlusion (7% vs. 11.6%; log-rank test p = 0.3) at a median of 13 months follow-up. CONCLUSION: In our study, emergency CAS in symptomatic patients might have a similar safety and efficacy profile to elective CAS at 3 months and long-term follow-up.

In-House Anesthesia and Interventional Radiology Technologist Support Optimize Mechanical Thrombectomy Workflow after Hours.

BACKGROUND AND PURPOSE: Prior literature suggests after-hours delay leads to poor functional outcomes in stroke patients undergoing thrombectomy. We aimed to evaluate the impact of time of presentation on mechanical thrombectomy (MT) metrics and its association with long-term functional outcome in an Interventional Radiology (IR) suite equipped operating room (OR) setting. METHODS: Retrospective review of prospectively maintained database on all stroke patients undergoing mechanical thrombectomy between January 2015 and December 2018 at our CSC. Work hours were defined by official OR work hours (Monday-Friday 7 AM and 5 PM) and after-hours as between 5 PM and 7 AM during weekdays and weekends as well as official hospital holidays. Primary outcome was 90-day modified Rankin Scale (mRS). Secondary outcomes included door to groin puncture time and procedural complications. RESULTS: A total of 315 patients were included in the analyses. 209 (66.4%) received mechanical thrombectomy after hours and 106 (33.6%) during work hours. There was no difference in the shift distribution of functional outcome on the mRS at 90 days (OR: 1.14, CI: 0.72-1.78, p=0.58) and the percentage of patients achieving functional independence (mRS 0-2) at 90 days (43.1% vs. 41.3%; p=0.83) between the after hour and work hour groups respectively. Similarly, there was no difference in median door to groin times and procedural complications among both groups, with significant year on year improvement in overall time metrics. CONCLUSIONS: Our study showed that undergoing MT during off-hours had similar functional outcomes when compared to MT during working hours in an OR setting. The after-hours deleterious effect might disappear when MT is performed in a system with 24-hours in-house Anesthesia and IR tech services.

REGIONAL AND AGE-RELATED VARIATIONS IN HAPTOGLOBIN CONCENTRATIONS IN STELLER SEA LIONS ( EUMETOPIAS JUBATUS) FROM ALASKA, USA.

Varying concentrations of the highly conserved acute phase response protein, haptoglobin, can indicate changes to the health and disease status of mammals, including the Steller sea lion (SSL; Eumetopias jubatus). To better understand factors relating to acute phase response in SSLs, circulating haptoglobin concentrations (Hp) were quantified in plasma collected from 1,272 individuals sampled near rookeries and haulouts off the coast of Alaska, US. We compared Hp in SSLs between sexes and among different age classes (young pups, young-of-the-year, yearlings, subadults, and adults) sampled within distinct regions in Alaska (Aleutian Islands, Gulf of Alaska, Southeast Alaska). Regional and age-related differences were observed, particularly in younger SSLs. No sex-related differences were detected. We identified weakly significant relationships between Hp and hematology measurements including white blood cell counts and hematocrit in young pups from the Aleutian Islands and Southeast Alaska. No relationship between Hp and body condition was found. Lastly, a nonlinear relationship of plasma Hp and whole blood total mercury concentrations (THg) was observed in SSLs from the endangered western distinct population segment in Alaska. These results demonstrated that regional variation in Hp, especially in younger SSLs, may reflect regional differences in health and circulating THg.

Exercise Increases Glucose Transporter-4 Levels on Peripheral Blood Mononuclear Cells.

PURPOSE: Glucose transporter 4 (GLUT4) plays a key role in the pathophysiology of type 2 diabetes. Glucose transporter 4 is upregulated in response to exercise, enhancing cellular glucose transport in skeletal muscle tissue. This mechanism appears to remain intact in individuals with insulin resistance. Details of the mechanism are poorly understood and are challenging to study due to the invasive nature of muscle biopsy. Peripheral blood mononuclear cells (PBMC) have documented insulin-sensitive GLUT4 activity and may serve as a proxy tissue for studying skeletal muscle GLUT4. The purpose of this study was to investigate whether GLUT4 in PBMC is affected by conditioning. METHODS: We recruited 16 student athletes from the cross-country running and skiing teams and fifteen sedentary students matched for age and sex from the University of Alaska Fairbanks. Peripheral blood mononuclear cells were collected with mononuclear cell separation tubes. The GLUT4 concentrations were measured using a commercially available enzyme linked immunosorbent assay. Additionally, correlations between PBMC GLUT4 and common indicators of insulin resistance were examined. RESULTS: Results indicate significantly higher PBMC GLUT4 levels in conditioned athletes than in their sedentary counterparts, similar to what has been documented in myocytes. Females were observed to have higher PBMC GLUT4 levels than males. Correlations were not detected between PBMC GLUT4 and hemoglobin A1c, glucose, insulin, homeostatic model assessment of insulin resistance, body mass index, or body fat. CONCLUSIONS: This study provides evidence to support exploration of PBMC as a proxy tissue for studying GLUT4 response to exercise or other noninsulin factors.