Intra-subject Correlation Research Articles

TENSOR GENERALIZED ESTIMATING EQUATIONS FOR LONGITUDINAL IMAGING ANALYSIS.

Longitudinal neuroimaging studies are becoming increasingly prevalent, where brain images are collected on multiple subjects at multiple time points. Analyses of such data are scientifically important, but also challenging. Brain images are in the form of multidimensional arrays, or tensors, which are characterized by both ultrahigh dimensionality and a complex structure. Longitudinally repeated images and induced temporal correlations add a further layer of complexity. Despite some recent efforts, there exist very few solutions for longitudinal imaging analyses. In response to the increasing need to analyze longitudinal imaging data, we propose several tensor generalized estimating equations (GEEs). The proposed GEE approach accounts for intra-subject correlation, and an imposed low-rank structure on the coefficient tensor effectively reduces the dimensionality. We also propose a scalable estimation algorithm, establish the asymptotic properties of the solution to the tensor GEEs, and investigate sparsity regularization for the purpose of region selection. We demonstrate the proposed method using simulations and by analyzing a real data set from the Alzheimer's Disease Neuroimaging Initiative.

Concurrent Radiation and Biological Therapy is Safe in Multiple Myeloma

The management of multiple myeloma (MM) has evolved in the modern era partially owing to the increasing number of biological therapeutics. Bortezomib, Daratumumab and Carfizomib have become standard of care treatments for MM. Nonetheless radiation continues to be an important treatment in the management of painful lytic lesions from MM. There is a concern for increased toxicity of treatment when given concurrently with biologicals. The goal of this study is to evaluate the side effect profile of radiation therapy while patients are concurrently being treated with biological agents. We conducted a retrospective study based on data collected from patients receiving radiotherapy at our institute from 2007 to 2017. A total of 130 patients (279 treatment sites) were included in this study with a median follow up time of 14 months. Patients had to be receiving a biological agent at least within one month prior to start and up to one month post receiving radiation therapy. Generalized estimating equations were used to assess difference in the probability of onset of acute side effects (within 4 weeks of treatment), sub-acute side effects (during 4 weeks and 6 months of treatment) and hematological events (Grade 3 or higher anemia, need for PRBC transfusion, need for platelet (Plt) transfusion and need for neupogen) between patient groups receiving or not receiving concurrent biological agents with RT. A compound symmetric covariance structure was assumed to control for intra-subject correlation. Linear mixed models were used to estimate the change in blood counts before and after treatment while adjusting for pre-treatment values. The mean age of all the patients in our cohort was 63.1 years (SD: 8.7), with 53 (58.9%) males and 37 (41.1%) females. The mean KPS score of all the cohort was 76. Further patient demographic information can be found in table 1. No significant difference in incidence of acute [OR = 1.65, 95% CI, (0.87, 3.13), p = 0.1270] or subacute [OR = 0.90, 95% CI, (0.40, 2.04), p = 0.8068] toxicities was found between patients with or without biological agents concurrently with RT. Furthermore, no significant difference in incidence of anemia and Neupogen requirement was noted between patients with or without biological agents concurrently with RT. However, patients receiving biological agents were more likely to have PRBC transfusion [OR = 5.05, 95% CI, (1.09, 23.44), p<0.05] and Plt transfusion [OR = 2.26, 95% CI, (1.01, 5.06), p<0.05]. Our study did not detect any significant toxicity rates from palliative radiation while patients were concurrently receiving biological agents. Palliative radiation therapy may be safely administered while patients are concurrently being treated with biological agents, without any major adverse effects. Biological therapies do not need to be held during RT.Abstract MO_35_2798; Table 1Treatment SiteNumber of PatientsSpine49Pelvis23Skull18Shoulder6Arm6Dose (Gy)Number of Patients≤ 20Gy5420-30Gy31≥ 30Gy17 Open table in a new tab

Two-Dimensional Canonical Correlation Analysis of the Logically Concatenated Cross Binary Pattern for Cross Pose Face Recognition

Face pose recognition is one of the challenging areas in computer vision. Cross-pose change causes the change in the information of face appearance. The maximization of intrasubject correlation helps to widen the intersubject differences which helps further in achieving pose invariance. In this paper, for cross pose recognition, the authors propose to maximize the cross pose correlation by using the logically concatenated cross binary pattern (LC-CBP) descriptor and two dimensional canonical correlation analysis (2DCCA). The LC-CBP descriptor extracts the local texture details of face images with low computation complexity and the 2DCCA explicitly searches for the maximization of the correlated features to retain most informative content. Joint feature consideration via 2DCCA helps in setting up a better correspondence between a discrete set of nonfrontal pose and the frontal pose of the same subject. Experimental results demonstrate the two dimensional canonical correlation LC-CBP descriptor along with intensity values improve the correlation.

Quantile estimations via modified Cholesky decomposition for longitudinal single-index models

Quantile regression is a powerful complement to the usual mean regression and becomes increasingly popular due to its desirable properties. In longitudinal studies, it is necessary to consider the intra-subject correlation among repeated measures over time to improve the estimation efficiency. In this paper, we focus on longitudinal single-index models. Firstly, we apply the modified Cholesky decomposition to parameterize the intra-subject covariance matrix and develop a regression approach to estimate the parameters of the covariance matrix. Secondly, we propose efficient quantile estimating equations for the index coefficients and the link function based on the estimated covariance matrix. Since the proposed estimating equations include a discrete indicator function, we propose smoothed estimating equations for fast and accurate computation of the index coefficients, as well as their asymptotic covariances. Thirdly, we establish the asymptotic properties of the proposed estimators. Finally, simulation studies and a real data analysis have illustrated the efficiency of the proposed approach.

Large inter- and intra-case variability of first generation tau PET ligand binding in neurodegenerative dementias

Imaging of pathological tau with positron emission tomography (PET) has the potential to allow early diagnosis of the dementias and monitoring of disease progression, including assessment of therapeutic interventions, in vivo. The first generation of tau PET tracers, including the carbazole flortaucipir and the 2-arylquinolines of the THK series, are now used in clinical research; however, concerns have been raised about off-target binding and low sensitivity.With the aim to determine the nature of tau pathology depicted by structurally distinct tau ligands we carried out a microscopic neuropathological evaluation in post-mortem human brain tissue of cases with primary and secondary tauopathies. Carbazole and 2-arylquinoline binding was only observed in cases with Alzheimer’s disease and one case with frontotemporal dementia and parkinsonism linked to chromosome 17 exhibiting a R406W MAPT mutation. In end stage Alzheimer’s disease cases, fluorescent imaging with the carbazole T726 and the 2-arylquinoline THK-5117 revealed high inter- and intra-case variability of tracer binding, and this was corroborated by quantitative phosphorimaging with the PET tracer [18F]THK-5117. Microscopic analysis of the pathological inclusions revealed that the fluorescent tracers preferentially bind to premature tau aggregates. Whilst T726 binding was limited to neuronal tau, THK-5117 additionally depicted neuritic tau. Neither tracer depicted tau in pre-symptomatic disease.Our results highlight limitations of the first generation of tau PET tracers, in particular lack of correlation between pathological tau load and tracer binding, limited sensitivity to tau in early disease, and high variability in tracer binding between and within cases. Concerns remain that these limitations may also affect the next generation tracers as they target the same high affinity binding site. Therefore, it is crucial to assess inter- and intra-subject correlation of tracer binding with pathological tau load in post-mortem tissue studies, and to rigorously assess novel tau PET tracers before translation into clinical studies.

Symptomatic Relief is Related to Serum Free Triiodothyronine Concentrations during Follow-up in Levothyroxine-Treated Patients with Differentiated Thyroid Cancer

Patients on levothyroxine-treatment frequently have complaints although TSH is within the reference range. Moreover, FT3 is often low in these patients. The clinical significance of this disequilibrium is studied here. We conducted a retrospective longitudinal study including 319 patients with differentiated thyroid carcinoma on LT4-medication (1.8 [1.6,2.1] µg/kg body weight). Patients were followed at 2309 visits for at median 63 [46,81] months. Association of reported complaints during follow-up with changes in thyroid parameters were analysed using a generalised linear mixed model accounting for within-variability and intra-subject correlations. 26% of patients expressed hypothyroid and 9.7% hyperthyroid complaints at any one visit, rates per visit being 6.5% and 2%, respectively. During follow-up, median changes in spans were as follows, LT4-dose 0.49 [IQR 0.29,0.72] µg/kg, FT3 1.77 [1.25,2.32] pmol/l, FT4 9.80 [6.70,12.8] pmol/l and TSH 1.25 [0.42,2.36] mIU/l. While rates of both hypothyroid or hyperthyroid symptoms were significantly related to all three thyroid parameters, the relationship of hypothyroid symptoms with FT3 extended to a below reference TSH range. Hypothyroid symptom relief was associated with both a T4 dose giving TSH-suppression below the lower reference limit and FT3 elevated further into the upper half of its reference range. In multivariable analysis, relationships between complaints and FT3 concentrations remained significant after adjusting for gender, age and BMI. Residual hypothyroid complaints in LT4-treated patients are specifically related to low FT3 concentrations. This supports an important role of FT3 for clinical decision making on dose adequacy, particularly in symptomatic athyreotic patients.

Effects of extremely low frequency electromagnetic fields on turkeys

Several studies have examined the potential biological effects of electromagnetic fields (EMF) on birds; however, little attention has been paid to the extremely low frequency (ELF; 0–300 Hz; 0–50 μT) radiation found in an urbanized environment. For monitoring the effects of ELF EMF, we used a turkey (Meleagris gallopavo) model, because the nucleated erythrocytes of turkeys contain β-adrenoceptors, and norepinephrine- (NE-) activated β-adrenoceptors have an important role in physiological and behavioral processes. Our aims were the following: 1) to investigate the intracellular mechanisms; 2) to compare the intracellular mechanisms in the treated and control groups over time, considering inter-individual differences and intra-subject correlations; 3) and to study the reversible nature of the response. The turkeys in the treatment group were treated in vivo with ELF EMF (50 Hz; 10 μT) for 3 wk after a 1-wk-long adaptation period. The animals were not exposed to ELF EMF during the regeneration period (5 wk following the exposure). The NE-activated β-adrenoceptor function was detected by measuring the amount of 3′5′-cyclic-adenosine-monophosphate (cAMP), and the biochemical enzyme parameters were defined. Repeated measurements of cAMP levels were analyzed using marginal models and a piecewise linear mixed model to compare treatment and control groups over time. According to our results, NE-activated β-adrenoceptor function was decreased in the treated birds in a time-dependent manner, while there were no differences between toxicological parameters in the serum, compared to the normal ranges. The decreased NE-dependent β-adrenoceptor function could be compensated by the homeostatic complex during the 5-wk regeneration period. Extended experimental periods and more sophisticated analysis methods may help prevent harmful environmental effects on birds; furthermore, these findings could affect public health and the economy.

Brain activity patterns induced by interrupting the cognitive processes with online advertising

As a result of the increasing role of online advertising and strong competition among advertisers, intrusive techniques are commonly used to attract web users’ attention. Moreover, since marketing content is usually delivered to the target audience when they are performing typical online tasks, like searching for information or reading online content, its delivery interrupts the web user’s current cognitive process. The question posed by many researchers in the field of online advertising is: how should we measure the influence of interruption of cognitive processes on human behavior and emotional state? Much research has been conducted in this field; however, most of this research has focused on monitoring activity in the simulated environment, or processing declarative responses given by users in prepared questionnaires. In this paper, a more direct real-time approach is taken, and the effect of the interruption on a web user is analyzed directly by studying the activity of his brain. This paper presents the results of an experiment that was conducted to find the brain activity patterns associated with interruptions of the cognitive process by showing internet advertisements during a text-reading task. Three specific aspects were addressed in the experiment: individual patterns, the consistency of these patterns across trials, and the intra-subject correlation of the individual patterns. Two main effects were observed for most subjects: a drop in activity in the frontal and prefrontal cortical areas across all frequency bands, and significant changes in the frontal/prefrontal asymmetry index.

Stability of Cortical Thinning in Persons at Increased Familial Risk for Major Depressive Disorder Across 8 Years

BackgroundA biological marker of vulnerability should precede onset of illness and be independent of disease course. We previously reported that cortical thinning may serve as a potential biomarker for risk for familial depression. We now test stability of cortical thinning across 8 years, and whether thinning mediates associations between familial risk and depressive traits. MethodsParticipants were from a three-generation family study of depression, where second- and third-generation offspring were characterized as being at high or low risk for depression based on the presence/absence of major depressive disorder in the first generation. The analysis includes 82 offspring with anatomical magnetic resonance imaging scans across two assessment waves conducted 7.8 years apart (SD = 1.3 years; range, 5.2–10.9 years). ResultsHigh-risk offspring had thinner bilateral superior and middle frontal gyri and left inferior parietal lobule at both time points. High intrasubject correlation (.60 <r < .91) and intraclass correlation (0.72–0.78) of thickness measures across time points was detected within the above regions; rank order by effect size and region was also preserved across time. The thinning was stable despite changes in scanning platform (Siemens Sonata vs. GE Signa), field strength (1.5T vs. 3T), and participant age and clinical course. Thinning at the first time point predicted anger and hostility at the second time point and mediated the relationship between familial risk and these traits. ConclusionsThe study provides evidence for cortical thinning as a stable biomarker for familial vulnerability for depressive illness, which supports the ability to detect persistent and clinically relevant anatomical findings regardless of magnetic resonance imaging platform.

Enabling robust assessment of QTc prolongation in early phase clinical trials.

Since the implementation of the International Conference on Harmonization (ICH) E14 guideline in 2005, regulators have required a "thorough QTc" (TQT) study for evaluating the effects of investigational drugs on delayed cardiac repolarization as manifested by a prolonged QTc interval. However, TQT studies have increasingly been viewed unfavorably because of their low cost effectiveness. Several researchers have noted that a robust drug concentration-QTc (conc-QTc) modeling assessment in early phase development should, in most cases, obviate the need for a subsequent TQT study. In December 2015, ICH released an "E14 Q&As (R3)" document supporting the use of conc-QTc modeling for regulatory decisions. In this article, we propose a simple improvement of two popular conc-QTc assessment methods for typical first-in-human crossover-like single ascending dose clinical pharmacology trials. The improvement is achieved, in part, by leveraging routinely encountered (and expected) intrasubject correlation patterns encountered in such trials. A real example involving a single ascending dose and corresponding TQT trial, along with results from a simulation study, illustrate the strong performance of the proposed method. The improved conc-QTc assessment will further enable highly reliable go/no-go decisions in early phase clinical development and deliver results that support subsequent TQT study waivers by regulators.

In Response

In Response

On the estimation of face recognition system performance using image variability information

The type and amount of variation that exists among images in facial image datasets significantly affects Face Recognition System Performance (FRSP). This points towards the development of an appropriate image Variability Measure (VM), as applied to face-type image datasets. Given VM, modeling of the relationship that exists between the image variability characteristics of facial image datasets and expected FRSP values, can be performed.Thus, this paper presents a novel method to quantify the overall data variability that exists in a given face image dataset. The resulting Variability Measure (VM) is then used to model FR system performance versus VM (FRSP/VM).Note that VM takes into account both the inter- and intra-subject class correlation characteristics of an image dataset. Using eleven publically available datasets of face images and four well-known FR systems, computer simulation based experimental results showed that FRSP/VM based prediction errors are confined in the region of 0–10%.

Validation of a quantitative method to measure neural respiratory drive in children during sleep

AimsQuantitatively measure and validate analysis of neural respiratory drive (NRD) using a commercial polysomnography system in children during sleep. MethodSurface electromyogram of the diaphragm (sEMGdi) recorded from primary snoring children were analysed. A subset was re-analysed to assess intra- and inter-investigator reproducibility. Effects of different band pass filter settings (20–100Hz vs 10–1000Hz) on sEMGdi amplitude were evaluated. ResultsMean sEMGdi from 45 children aged 4.38 years (median; IQR 3.00–7.96) was 5.05μV (SD 2.73). The sEMGdi had a high intra-subject intraclass correlation coefficient (ICC) of 0.88. sEMGdi analysis was reproducible with high ICC between occasions (0.99; 95% CI 0.98–0.99) and between investigators (0.98; 95% CI 0.97–0.99). There was also a high ICC (0.99, 95% CI 0.96–1.00) between the sEMGdi measured using different band-pass filter settings. Age and BMI were negative predictors of sEMGdi (p<0.0001 and p=0.0004 respectively). ConclusionNRD in children during sleep as assessed by sEMGdi can be quantified in a reliable and reproducible fashion.

Housing Insecure HIV Patients Have Higher Positive Gonorrhea and Chlamydia Test Results but Lower Testing Rates in a Primary Care Setting

BackgroundHousing insecure HIV-infected patients experience poor treatment outcomes, but whether these outcomes are due to less engagement in care or differential quality of care is unknown. We evaluated gonorrhea and chlamydia (GC-CT) testing among HIV-infected patients to assess whether differences exist by housing status and whether differences are due to frequency of primary care visits or services delivered when visits are made.MethodsWe used retrospective cohort analysis to assess GC-CT testing in patients establishing care at an urban HIV clinic in San Francisco between February, 2013 – December, 2014 who had at least one subsequent primary care visit. The predictor variable of homelessness was defined as having stayed outdoors, in shelters, in vehicles, or in places not made for habitation during the last year and was evaluated during social work intake. The primary outcome was having GC-CT testing at a primary care visit. The probability of GC-CT testing at a primary care visit was calculated using logistic regression modeling with random effects to handle intra-subject correlations for repeated measurements. We adjusted for age, race/ethnicity, methamphetamine use, alcohol use, sexual orientation, prior positive GC-CT test, recent GC-CT test and visit frequency. Comparison of GC-CT test results by housing status was made using chi2.ResultsOf 323 patients, mean age was 41.4 years, 91% were male, 50% non-Latino White, and 45% were homeless. 204 patients (63%) had GC-CT testing done, and 138 (37%) had testing at primary care visits. A median visit frequency for housed patients was 1.42 visits/180 days v 1.61 for homeless patients (p-value 0.36). Average follow-up time was 472 days (sd 292 days). Homelessness was associated with lower odds of GC-CT testing during follow-up (aOR 0.60; 95% CI 0.40, 0.96 p-value 0.032). 28% of first GC-CT tests were positive in homeless v. 12% in housed patients (p-value 0.025).ConclusionHomeless patients had a higher rate of positive GC-CT on first test but 40% lower odds of having GC-CT testing at primary care visits despite controlling for visit frequency, recent testing and history of positive GC-CT. Further evaluation of disparities in GC-CT testing for homeless patients is warranted.Disclosures All authors: No reported disclosures.

Instantaneous Metabolic Cost of Walking: Joint-Space Dynamic Model with Subject-Specific Heat Rate.

A subject-specific model of instantaneous cost of transport (ICOT) is introduced from the joint-space formulation of metabolic energy expenditure using the laws of thermodynamics and the principles of multibody system dynamics. Work and heat are formulated in generalized coordinates as functions of joint kinematic and dynamic variables. Generalized heat rates mapped from muscle energetics are estimated from experimental walking metabolic data for the whole body, including upper-body and bilateral data synchronization. Identified subject-specific energetic parameters—mass, height, (estimated) maximum oxygen uptake, and (estimated) maximum joint torques—are incorporated into the heat rate, as opposed to the traditional in vitro and subject-invariant muscle parameters. The total model metabolic energy expenditure values are within 5.7 ± 4.6% error of the measured values with strong (R2 > 0.90) inter- and intra-subject correlations. The model reliably predicts the characteristic convexity and magnitudes (0.326–0.348) of the experimental total COT (0.311–0.358) across different subjects and speeds. The ICOT as a function of time provides insights into gait energetic causes and effects (e.g., normalized comparison and sensitivity with respect to walking speed) and phase-specific COT, which are unavailable from conventional metabolic measurements or muscle models. Using the joint-space variables from commonly measured or simulated data, the models enable real-time and phase-specific evaluations of transient or non-periodic general tasks that use a range of (aerobic) energy pathway similar to that of steady-state walking.

Liothyronine Improves Biochemical Control of Congenital Hypothyroidism in Patients with Central Resistance to Thyroid Hormone

To assess whether adding liothyronine (LT3) to levothyroxine (LT4) monotherapy normalizes serum thyrotropin (TSH) and thyroxine (T4) concentrations in children with congenital hypothyroidism and central resistance to thyroid hormone. We retrospectively studied 12 patients with congenital hypothyroidism and central resistance to thyroid hormone (6 treated with LT3+LT4 combined therapy and 6 treated with LT4 monotherapy). In patients receiving combined therapy, we compared serum concentrations of TSH, T4, and triiodothyronine before and after addition of LT3. We used repeated measures analysis to compare thyroid function in participants receiving combined therapy vs monotherapy, while accounting for age and intrasubject correlation. In patients receiving combined therapy, the addition of LT3 was associated with normalization of mean TSH (9.2 vs 4.5 mIU/L, P=.002), a lower proportion of TSH values greater than 10 mIU/L (35% vs 8%, P=.03), and a decrease in mean serum T4 by 23±9% (P<.001). Compared with patients receiving LT4 monotherapy, patients receiving combined therapy had lower mean TSH (8.5±0.9 vs 4.3±0.4, P<.001), lower odds of TSH elevation greater than 10 mIU/L (OR 0.20, 95% CI 0.10-0.41, P<.001), and lower odds of T4 elevation (OR 0.21, 95% CI 0.04-1.09, P=.06). LT3 treatment did not increase serum T3 levels significantly. The addition of LT3 to LT4 monotherapy facilitates normalization of both serum TSH and T4 in patients with congenital hypothyroidism and central resistance to thyroid hormone. Larger prospective studies are needed to confirm these findings and to determine the effect of combined therapy on neurodevelopmental outcomes.

Test-Retest of Long Latency Auditory Evoked Potentials (P300) with Pure Tone and Speech Stimuli.

Introduction Long latency auditory evoked potentials, especially P300, have been used for clinical evaluation of mental processing. Many factors can interfere with Auditory Evoked Potential - P300 results, suggesting large intra and inter-subject variations. Objective The objective of the study was to identify the reliability of P3 components (latency and amplitude) over 4–6 weeks and the most stable auditory stimulus with the best test-retest agreement. Methods Ten normal-hearing women participated in the study. Only subjects without auditory processing problems were included. To determine the P3 components, we elicited long latency auditory evoked potential (P300) by pure tone and speech stimuli, and retested after 4–6 weeks using the same parameters. We identified P300 latency and amplitude by waveform subtraction. Results We found lower coefficient of variation values in latency than in amplitude, with less variability analysis when speech stimulus was used. There was no significant correlation in latency measures between pure tone and speech stimuli, and sessions. There was a significant intrasubject correlation between measures of latency and amplitude. Conclusion These findings show that amplitude responses are more robust for the speech stimulus when compared with its pure tone counterpart. The P300 indicated stability for latency and amplitude measures when the test-retest was applied. Reliability was higher for amplitude than for latency, with better agreement when the pure tone stimulus was used. However, further research with speech stimulus is needed to clarify how these stimuli are processed by the nervous system.

Comparison of the correlations between impact loading rates and peak accelerations measured at two different body sites: Intra- and inter-subject analysis

BackgroundHigh average (VALR) and instantaneous vertical loading rates (VILR) during impact have been associated with many running-related injuries. Peak acceleration (PA), measured with an accelerometer, has provided an alternative method to estimate impact loading during outdoor running. This study sought to compare both intra- and inter-subject correlations between vertical loading rates and PA measured at two body sites during running. MethodsGround reaction force data were collected from 10 healthy adults (age=23.6±3.8 years) during treadmill running at different speeds and inclination surfaces. Concurrently, PAs at the lateral malleoli and the distal tibia were measured using synchronized accelerometers. ResultsWe found significant positive intra-subject correlation between loading rates and PA at the lateral malleoli (r=0.561–0.950, p<0.001) and the distal tibia (r=0.486–0.913, p<0.001). PA measured at the lateral malleoli showed stronger correlation with loading rates (p=0.004) than the measurement at the distal tibia. On the other hand, inter-subject variances were observed in the association between PA and vertical loading rates. The inter-subject variances at the distal tibia were 3.88±3.09BW/s and 5.69±3.05BW/s in VALR and VLIR respectively. Similarly, the inter-subject variances in the measurement at lateral malleoli were 5.24±2.85BW/s and 6.67±2.83BW/s in VALR and VLIR respectively. ConclusionsPA measured at lateral malleoli has stronger correlation with VALR or VILR than the measurement at distal tibia. Caution is advised when using PA to conduct inter-subject comparisons of vertical loading rates during running.

Abstract WP119: Effects of Indirect Revascularization with Synangiosis in New Vessel Formation in an Animal Model of Cerebral Ischemia.

Objective: In order to study the mechanisms associated with neovascularization after indirect bypass (EDAS), we have developed a mice model of synangiosis and cerebral ischemia. Method: Healthy 12-24 week old male C57/BL6J mice were used. The temporalis muscle served as donor for the external carotid artery vessels through a window in the temporalis bone. The distal MCA was ligated after opening the dura. The temporalis muscle was reattached in direct apposition to the ischemic brain surface. Animals were sacrificed at one month and their heads were prepared in block. Brain slices were stained with CD31 (endothelial cell marker), Ki67 (proliferation maker), and DAPI (nuclear marker) antibodies. Confocal laser microscopy was used for immunofluorescent imaging. Standardized relative quantification of immunofluorescence staining was performed using ImageJ following the Arqués protocol. Inferential comparisons among groups were performed with a generalized linear model. Data was nested in the model by animal to account for intrasubject correlation. Results: A total of 12 mice were operated. One subject died after surgery (attrition rate 8%). All other subjects displayed no deficits. The number of DAPI+ cells/image was no different between the synangiosis and the control side. The index CD31/DAPI was significantly higher in the synangiosis side (mean 0.90 ± 1.13 vs. controls: 0.60 ± 0.65, p&lt;0.001). The proliferation index Ki67/DAPI was significantly higher in the synangiosis side (mean 0.21 ± 0.08 vs. controls: 0.12 ± 0.05, p=0.03). There was 8% colocalization of the 3 markers on the synangiosis side and none on the controls. Conclusions: Our model of synangiosis in mice was well tolerated and produced quantifiable neovascularization in the brain as indicated by the neovascularization indexes observed in confocal microscopy. This model of synangiosis is a promising tool for future studies of neovascularization and collateral formation in individuals with ischemia.

Abstract WP131: Effects Of EDAS Surgery On The Circulating Angiogenic Factors Of Patients With Moyamoya And Intracranial Atherosclerosis.

Objective: To evaluate the levels of circulating angiogenic factors in patients with moyamoya disease (MMD), intracranial atherosclerosis (ICAS), and controls, and the effects of EDAS in their levels. Methods: Prospective longitudinal study of angiogenic factors in 22 patients with MMD, ICAS, and controls. Patients with MMD and ICAS underwent EDAS surgery. Control cases had cranial surgery for non-vascular or tumor pathology. Angiogenic factors were measured at baseline and 7 days after surgery. Log-corrected levels were compared between groups. Multivariate analysis of variance (MANOVA) was used to examine differences within pairs and between groups. Regression mixed models were built to account for intrasubject correlation and evaluate the association of angiogenic levels with group and treatment. Results: Mean age was 41 ± 11 in MMD, 65 ± 16 in ICAS, and 51 ± 19 in controls. There were 83% females in the MMD group, 44% in ICAS, and 43% in controls. Patients with MMD had significantly higher levels of PDGFAA (568.8 pg/ml), vs ICAS (165.9pg/mL), and controls (38.4 pg/mL) p=0.007; PDGFBB (1449.7 pg/mL), vs. ICAS (141.2 pg/mL), and controls (65.2 pg/mL) p=0.03; TGFB1 (24.5 ng/mL), vs. ICAS (13.8 ng/mL), and controls (6.2 ng/mL) p=0.006; TSP1 (128.5 ng/mL), vs. ICAS (91.7 ng/mL), and controls (9 ng/mL) p=0.0007. After surgery (EDAS for MMD and ICAS vs. cranial surgery for controls) levels of PDGFAA, PDGFBB, and TGFB1 increased on the ICAS and control groups eliminating the baseline differences. EDAS, independently from etiology, affected the levels of pro-angiogenic TGFB2 (EDAS: 290 pg/mL, controls: 161 pg/mL), and BMP2 (EDAS: 153 pg/mL, controls: 109 pg/mL) p&lt;0.02. EDAS also increased the levels of the anti-angiogenic TSP2 (EDAS: 54.5 ng/mL, controls: 29 ng/mL) p=0.02. Conclusion: Patients with MMD have baseline higher levels of pro-angiogenic factors PDGFAA, PDGFBB, and TGFB1, involved in vessel maturation. EDAS, independent from etiology, affected the levels of TGFB2, BMP2 and TSP2, cytokines involved in vessel maturation, increased vascular permeability, and modulation of cell migration, respectively.