Left ventricular hypertrophy and left atrial size are associated with ischemic strokes among non-vitamin K antagonist oral anticoagulant users

BACKGROUND

Ischemic strokes (IS) occurring in patients taking non-vitamin K antagonist oral anticoagulants (NOACs) are becoming increasingly more frequent. We aimed to determine the clinical, echocardiographic, and neuroimaging markers associated with developing IS in patients taking NOACs for atrial fibrillation.

METHODS

From a quaternary care center, clinical/radiologic data were collected from consecutive NOAC users with IS and age-matched controls without IS. Brain MRIs were reviewed for markers of cerebral small vessel disease. Variables with significant differences between groups were entered into a multivariable regression model to determine predictors of IS. Among IS patients, a Cox regression analysis was constructed to determine predictors of IS recurrence during follow-up.

RESULTS

112 patients with IS and 94 controls were included in the study. Variables significantly different between groups included apixaban use, dabigatran use, prior cerebrovascular events, hemoglobin A1c (HbA1c), left ventricular hypertrophy, left atrial volume index, and severe white matter hyperintensities. After multivariable adjustment, prior cerebrovascular events (aOR 23.86, 95% CI [6.02-94.48]), HbA1c levels (aOR 2.36, 95% CI [1.39-3.99]), left ventricular hypertrophy (aOR 2.73, 95% CI [1.11-6.71]) and left atrial volume index (aOR 1.05, 95% CI [1.01-1.08]) increased the risk of stroke, whereas apixaban use appeared to decrease the risk (aOR 0.38, 95% CI [0.16-0.92]). Malignancy was associated with IS recurrence (aHR 4.90, 95% CI [1.35-18.42]) after adjustment for age and chronic renal failure.

CONCLUSIONS

Prior cerebrovascular events, diabetes, left ventricular hypertrophy, and increased left atrial size are risk factors for developing an IS among NOAC users.

Peak width of skeletonized mean diffusivity and cognitive performance in cerebral amyloid angiopathy

Background

Cerebral Amyloid Angiopathy (CAA) is a cerebral small vessel disease that can lead to microstructural disruption of white matter (WM), which can be measured by the Peak Width of Skeletonized Mean Diffusivity (PSMD). We hypothesized that PSMD measures would be increased in patients with CAA compared to healthy controls (HC), and increased PSMD is associated with lower cognitive scores in patients with CAA.

Methods

Eighty-one probable CAA patients without cognitive impairment who were diagnosed with Boston criteria and 23 HCs were included. All subjects underwent an advanced brain MRI with high-resolution diffusion-weighted imaging (DWI). PSMD scores were quantified from a probabilistic skeleton of the WM tracts in the mean diffusivity (MD) image using a combination of fractional anisotropy (FA) and the FSL Tract-Based Spatial Statistics (TBSS) algorithm (www.psmd-marker.com). Within CAA cohort, standardized z-scores of processing speed, executive functioning and memory were obtained.

Results

The mean of age and sex were similar between CAA patients (69.6 ± 7.3, 59.3% male) and HCs (70.6 ± 8.5, 56.5% male) (p = 0.581 and p = 0.814). PSMD was higher in the CAA group [(4.13 ± 0.94) × 10-4 mm2/s] compared to HCs [(3.28 ± 0.51) × 10-4 mm2/s] (p < 0.001). In a linear regression model corrected for relevant variables, diagnosis of CAA was independently associated with increased PSMD compared to HCs (ß = 0.45, 95% CI 0.13-0.76, p = 0.006). Within CAA cohort, higher PSMD was associated with lower scores in processing speed (p < 0.001), executive functioning (p = 0.004), and memory (0.047). Finally, PSMD outperformed all other MRI markers of CAA by explaining most of the variance in models predicting lower scores in each cognitive domain.

Discussion

Peak Width of Skeletonized Mean Diffusivity is increased in CAA, and it is associated with worse cognitive scores supporting the view that disruption of white matter has a significant role in cognitive impairment in CAA. As a robust marker, PSMD can be used in clinical trials or practice.

Abstract 162: Molecular And Microstructural Alterations In Cerebral Amyloid Angiopathy-related Hemorrhagic Manifestations

Background and Purpose: We aimed to compare the amyloid load and degree of microstructural injury among Cerebral Amyloid Angiopathy (CAA) patients with either higher lobar cerebral microbleed (CMB) counts or higher cortical superficial siderosis (cSS) extent against CAA patients with lower hemorrhagic load.

Methods: The study included 38 cognitively healthy probable CAA patients with lobar intracerebral hemorrhage (ICH) and 38 age, sex-matched healthy controls (HC) who underwent advanced MRI, and Pittsburgh Compound B (PiB) PET scans. Patients were categorized into CMB-Dominant (CMB-D) and cSS-Dominant (cSS-D) based on the number and extent of CMB and cSS using previously identified cutoffs (Figure). The mean global cortical amyloid load was calculated from PiB-PET scans and represented by PiB-DVR. Within the CAA cohort, the Peak Width of Skeletonized Mean Diffusivity (PSMD) was calculated from diffusion MRIs and used as a marker of microstructural integrity.

Results: Patients with CAA had significantly higher PiB-DVR than HCs (1.40±0.24 vs. 1.19±0.22, p<0.001). Both CMB-D and cSS-D CAA patients had significantly higher amyloid and increased (worse) PSMD compared to CAA patients with a non-dominant low hemorrhagic load (Figure). These results did not change in separate regression models corrected for age and sex. PiB-DVR significantly correlated with increased PSMD (r=0.346, p=0.033).

Conclusions: Our findings support the view that vascular amyloid load drives higher CMB counts, more extensive cSS, and microstructural injury in patients with CAA. Furthermore, the correlations among these markers suggest that these MRI-based categorizations (CMB-D and cSS-D patients) can be used for disease staging and further research.

Improving detection of cerebral small vessel disease aetiology in patients with isolated lobar intracerebral haemorrhage

BACKGROUND AND PURPOSE

We evaluate whether non-haemorrhagic imaging markers (NHIM) (white matter hyperintensity patterns, lacunes and enlarged perivascular spaces (EPVS)) can discriminate cerebral amyloid angiopathy (CAA) from hypertensive cerebral small vessel disease (HTN-cSVD) among patients with isolated lobar intracerebral haemorrhage (isolated-LICH).

METHODS

In patients with isolated-LICH, four cSVD aetiologic groups were created by incorporating the presence/distribution of NHIM: HTN-cSVD pattern, CAA pattern, mixed NHIM and no NHIM. CAA pattern consisted of patients with any combination of severe centrum semiovale EPVS, lobar lacunes or multiple subcortical spots pattern. HTN-cSVD pattern consisted of any HTN-cSVD markers: severe basal ganglia PVS, deep lacunes or peribasal ganglia white matter hyperintensity pattern. Mixed NHIM consisted of at least one imaging marker from either pattern. Our hypothesis was that patients with HTN-cSVD pattern/mixed NHIM would have a higher frequency of left ventricular hypertrophy (LVH), which is associated with HTN-cSVD.

RESULTS

In 261 patients with isolated-LICH, CAA pattern was diagnosed in 93 patients, HTN-cSVD pattern in 53 patients, mixed NHIM in 19 patients and no NHIM in 96 patients. The frequency of LVH was similar among those with HTN-cSVD pattern and mixed NHIM (50% vs 39%, p=0.418) but was more frequent in HTN-cSVD pattern compared with CAA pattern (50% vs 20%, p<0.001). In a regression model, HTN-cSVD pattern (OR: 7.38; 95% CI 2.84 to 19.20) and mixed NHIM (OR: 4.45; 95% CI 1.25 to 15.90) were found to be independently associated with LVH.

CONCLUSION

Among patients with isolated-LICH, NHIM may help differentiate HTN-cSVD from CAA, using LVH as a marker for HTN-cSVD.

Peak width of skeletonized mean diffusivity in cerebral amyloid angiopathy: Spatial signature, cognitive, and neuroimaging associations

Background

Peak width of skeletonized mean diffusivity (PSMD) is a promising diffusion tensor imaging (DTI) marker that shows consistent and strong cognitive associations in the context of different cerebral small vessel diseases (cSVD).

Purpose

Investigate whether PSMD (1) is higher in patients with Cerebral Amyloid Angiopathy (CAA) than those with arteriolosclerosis; (2) can capture the anteroposterior distribution of CAA-related abnormalities; (3) shows similar neuroimaging and cognitive associations in comparison to other classical DTI markers, such as average mean diffusivity (MD) and fractional anisotropy (FA).

Materials and methods

We analyzed cross-sectional neuroimaging and neuropsychological data from 90 non-demented memory-clinic subjects from a single center. Based on MRI findings, we classified them into probable-CAA (those that fulfilled the modified Boston criteria), subjects with MRI markers of cSVD not attributable to CAA (presumed arteriolosclerosis; cSVD), and subjects without evidence of cSVD on MRI (non-cSVD). We compared total and lobe-specific (frontal and occipital) DTI metrics values across the groups. We used linear regression models to investigate how PSMD, MD, and FA correlate with conventional neuroimaging markers of cSVD and cognitive scores in CAA.

Results

PSMD was comparable in probable-CAA (median 4.06 × 10^–4 mm²/s) and cSVD (4.07 × 10^–4 mm²/s) patients, but higher than in non-cSVD (3.30 × 10^–4 mm²/s; p < 0.001) subjects. Occipital-frontal PSMD gradients were higher in probable-CAA patients, and we observed a significant interaction between diagnosis and region on PSMD values [F(2, 87) = 3.887, p = 0.024]. PSMD was mainly associated with white matter hyperintensity volume, whereas MD and FA were also associated with other markers, especially with the burden of perivascular spaces. PSMD correlated with worse executive function (β = −0.581, p < 0.001) and processing speed (β = −0.463, p = 0.003), explaining more variance than other MRI markers. MD and FA were not associated with performance in any cognitive domain.

Conclusion

PSMD is a promising biomarker of cognitive impairment in CAA that outperforms other conventional and DTI-based neuroimaging markers. Although global PSMD is similarly increased in different forms of cSVD, PSMD’s spatial variations could potentially provide insights into the predominant type of underlying microvascular pathology.

Idiopathic primary intraventricular hemorrhage and cerebral small vessel disease

BACKGROUND

Although primary intraventricular hemorrhage is frequently due to trauma or vascular lesions, the etiology of idiopathic primary intraventricular hemorrhage (IP-IVH) is not defined.

AIMS

Herein, we test the hypothesis that cerebral small vessel diseases (cSVD) including hypertensive cSVD (HTN-cSVD) and cerebral amyloid angiopathy are associated with IP-IVH.

METHODS

Brain magnetic resonance imaging from consecutive patients (January 2011 to September 2019) with non-traumatic intracerebral hemorrhage from a single referral center were reviewed for the presence of HTN-cSVD (defined by strictly deep or mixed-location intracerebral hemorrhage/cerebral microbleeds) and cerebral amyloid angiopathy (applying modified Boston criteria).

RESULTS

Forty-six (4%) out of 1276 patients were identified as having IP-IVH. Among these, the mean age was 74.4 ± 12.2 years and 18 (39%) were females. Forty (87%) had hypertension, and the mean initial blood pressure was 169.2 ± 40.4/88.8 ± 22.2 mmHg. Of the 35 (76%) patients who received a brain magnetic resonance imaging, two (6%) fulfilled the modified Boston criteria for possible cerebral amyloid angiopathy and 10 (29%) for probable cerebral amyloid angiopathy. Probable cerebral amyloid angiopathy was found at a similar frequency when comparing IP-IVH patients to the remaining patients with primary intraparenchymal hemorrhage (P-IPH) (27%, p = 0.85). Furthermore, imaging evidence for HTN-cSVD was found in 8 (24%) patients with IP-IVH compared to 209 (28%, p = 0.52) patients with P-IPH.

CONCLUSIONS

Among IP-IVH patients, cerebral amyloid angiopathy was found in approximately one-third of patients, whereas HTN-cSVD was detected in 23%-both similar rates to P-IPH patients. Our results suggest that both cSVD subtypes may be associated with IP-IVH.

Effect of vascular amyloid on white matter disease is mediated by vascular dysfunction in cerebral amyloid angiopathy

We postulated that vascular dysfunction mediates the relationship between amyloid load and white matter hyperintensities (WMH) in cerebral amyloid angiopathy (CAA). Thirty-eight cognitively healthy patients with CAA (mean age 70 ± 7.1) were evaluated. WMH was quantified and expressed as percent of total intracranial volume (pWMH) using structural MRI. Mean global cortical Distribution Volume Ratio representing Pittsburgh Compound B (PiB) uptake (PiB-DVR) was calculated from PET scans. Time-to-peak [TTP] of blood oxygen level-dependent response to visual stimulation was used as an fMRI measure of vascular dysfunction. Higher PiB-DVR correlated with prolonged TTP (r = 0.373, p = 0.021) and higher pWMH (r = 0.337, p = 0.039). Prolonged TTP also correlated with higher pWMH (r = 0.485, p = 0.002). In a multivariate linear regression model, TTP remained independently associated with pWMH (p = 0.006) while PiB-DVR did not (p = 0.225). In a bootstrapping model, TTP had a significant indirect effect (ab = 0.97, 95% CI: 0.137-2.461), supporting that the association between PiB-DVR and pWMH is mediated by TTP response. There was no longer a direct effect independent of the hypothesized pathway. Our study suggests that the effect of vascular amyloid load on white matter disease is mediated by vascular dysfunction in CAA. Amyloid lowering strategies might prevent pathophysiological processes leading to vascular dysfunction, therefore limiting ischemic brain injury.

Cerebellar atrophy and its implications on gait in cerebral amyloid angiopathy

OBJECTIVE

Recent data suggest that cerebral amyloid angiopathy (CAA) causes haemorrhagic lesions in cerebellar cortex as well as subcortical cerebral atrophy. However, the potential effect of CAA on cerebellar tissue loss and its clinical implications have not been investigated.

METHODS

Our study included 70 non-demented patients with probable CAA, 70 age-matched healthy controls (HCs) and 70 age-matched patients with Alzheimer's disease (AD). The cerebellum was segmented into percent of cerebellar subcortical volume (pCbll-ScV) and percent of cerebellar cortical volume (pCbll-CV) represented as percent (p) of estimated total intracranial volume. We compared pCbll-ScV and pCbll-CV between patients with CAA, HCs and those with AD. Gait velocity (metres/second) was used to investigate gait function in patients with CAA.

RESULTS

Patients with CAA had significantly lower pCbll-ScV compared with both HC (1.49±0.1 vs 1.73±0.2, p<0.001) and AD (1.49±0.1 vs 1.66±0.24, p<0.001) and lower pCbll-CV compared with HCs (6.03±0.5 vs 6.23±0.6, p=0.028). Diagnosis of CAA was independently associated with lower pCbll-ScV compared with HCs (p<0.001) and patients with AD (p<0.001) in separate linear regression models adjusted for age, sex and presence of hypertension. Lower pCbll-ScV was independently associated with worse gait velocity (β=0.736, 95% CI 0.28 to 1.19, p=0.002) in a stepwise linear regression analysis including pCbll-CV along with other relevant variables.

INTERPRETATION

Patients with CAA show more subcortical cerebellar atrophy than HC or patients with AD and more cortical cerebellar atrophy than HCs. Reduced pCbll-ScV correlated with lower gait velocity in regression models including other relevant variables. Overall, this study suggests that CAA causes cerebellar injury, which might contribute to gait disturbance.

Abstract 69: Extent Of Tau And Its Cognitive Implications In Cerebral Amyloid Angiopathy

Background: Tau pathology is an important component of Alzheimer’s Disease but its extent and impact in cognitively healthy patients with cerebral amyloid angiopathy (CAA) are not clear. We compared in vivo tau stages estimated from the patterns of tau PET tracer uptake in patients with CAA and healthy controls (HC) and explored its relationship with amyloid burden and cognitive function in CAA.

Methods: The study included 50 cognitively healthy probable CAA patients (mean age 70±7.6) and 50 age-, sex-matched HCs (mean age 70±7.5) who underwent MRI, Pittsburgh compound B (PiB, for amyloid) and 18 F-flortaucipir (FTP, for tau) PET imaging. Mean global cortical PiB uptake was calculated. Tau stages were estimated based on the distribution pattern of cortical FTP uptake and grouped into three categories (PET Braak Staging, Figure). Within the CAA cohort, standardized z-scores of memory, processing speed and executive function testing were obtained.

Results: In the whole group, tau stages significantly correlated with age (rho=0.407, p<0.001) and global cortical PiB uptake (rho=0.554, p<0.001). Patients with CAA were more likely to exhibit more extensive tau (Stage III-VI) compared to HCs in univariate analyses (Figure, p=0.003). In a logistic regression model, more extensive tau independently associated with age (p=0.001) and PiB uptake (p<0.001) but not with the CAA diagnosis (p=0.264). Within the CAA cohort, tau stage was again independently associated with PiB uptake (p=0.002), but it did not show any association with scores of cognitive domains in univariate or multivariate models (p>0.2 for all comparisons).

Conclusion: Our results show that patients with CAA have higher PET Braak tau stages when compared to similarly aged HCs but this difference disappeared after controlling for amyloid load. Extent of tau did not correlate with cognitive scores in CAA. Overall, tau stages appear to be driven by amyloid without clinical impact in cognitively healthy CAA patients.

OUP accepted manuscript

The impact of vascular lesions on cognition is location dependent. Here, we assessed the contribution of small vessel disease lesions in the corpus callosum to vascular cognitive impairment in cerebral amyloid angiopathy, as a model for cerebral small vessel disease. Sixty-five patients with probable cerebral amyloid angiopathy underwent 3T magnetic resonance imaging, including a diffusion tensor imaging scan, and neuropsychological testing. Microstructural white-matter integrity was quantified by fractional anisotropy and mean diffusivity. Z-scores on individual neuropsychological tests were averaged into five cognitive domains: information processing speed, executive functioning, memory, language and visuospatial ability. Corpus callosum lesions were defined as haemorrhagic (microbleeds or larger bleeds) or ischaemic (microinfarcts, larger infarcts and diffuse fluid-attenuated inversion recovery hyperintensities). Associations between corpus callosum lesion presence, microstructural white-matter integrity and cognitive performance were examined with multiple regression models. The prevalence of corpus callosum lesions was confirmed in an independent cohort of memory clinic patients with and without cerebral amyloid angiopathy (n = 82). In parallel, we assessed corpus callosum lesions on ex vivo magnetic resonance imaging in cerebral amyloid angiopathy patients (n = 19) and controls (n = 5) and determined associated tissue abnormalities with histopathology. A total number of 21 corpus callosum lesions was found in 19/65 (29%) cerebral amyloid angiopathy patients. Corpus callosum lesion presence was associated with reduced microstructural white-matter integrity within the corpus callosum and in the whole-brain white matter. Patients with corpus callosum lesions performed significantly worse on all cognitive domains except language, compared with those without corpus callosum lesions after correcting for age, sex, education and time between magnetic resonance imaging and neuropsychological assessment. This association was independent of the presence of intracerebral haemorrhage, whole-brain fractional anisotropy and mean diffusivity, and white-matter hyperintensity volume and brain volume for the domains of information processing speed and executive functioning. In the memory clinic patient cohort, corpus callosum lesions were present in 14/54 (26%) patients with probable and 2/8 (25%) patients with possible cerebral amyloid angiopathy, and in 3/20 (15%) patients without cerebral amyloid angiopathy. In the ex vivo cohort, corpus callosum lesions were present in 10/19 (53%) patients and 2/5 (40%) controls. On histopathology, ischaemic corpus callosum lesions were associated with tissue loss and demyelination, which extended beyond the lesion core. Together, these data suggest that corpus callosum lesions are a frequent finding in cerebral amyloid angiopathy, and that they independently contribute to cognitive impairment through strategic microstructural disruption of white-matter tracts.

Lacunes, Microinfarcts, and Vascular Dysfunction in Cerebral Amyloid Angiopathy

OBJECTIVE

To analyze the relationship of lacunes with cortical cerebral microinfarcts (CMIs), to assess their association with vascular dysfunction, and to evaluate their effect on the risk of incident intracerebral hemorrhage (ICH) in cerebral amyloid angiopathy (CAA).

METHODS

The count and topography of lacunes (deep/lobar), CMIs, and white matter hyperintensity (WMH) volume were retrospectively analyzed in a prospectively enrolled CAA cohort that underwent high-resolution research MRIs. The relationship of lacunes with CMIs and other CAA-related markers including time to peak (TTP) of blood oxygen level-dependent signal, an established measure of vascular dysfunction, was evaluated in multivariate models. Adjusted Cox regression models were used to investigate the relationship between lacunes and incident ICH.

RESULTS

The cohort consisted of 122 patients with probable CAA without dementia (mean age, 69.4 ± 7.6 years). Lacunes were present in 31 patients (25.4%); all but one were located in lobar regions. Cortical CMIs were more common in patients with lacunes compared to patients without lacunes (51.6% vs 20.9%, p = 0.002). TTP was not associated with either lacunes or CMIs (both p > 0.2) but longer TTP response independently correlated with higher WMH volume (p = 0.001). Lacunes were associated with increased ICH risk in univariate and multivariate Cox regression models (p = 0.048 and p = 0.026, respectively).

CONCLUSIONS

Our findings show a high prevalence of lobar lacunes, frequently coexisting with CMIs in CAA, suggesting that these 2 lesion types may be part of a common spectrum of CAA-related infarcts. Lacunes were not related to vascular dysfunction but predicted incident ICH, favoring severe focal vessel involvement rather than global ischemia as their mechanism.

Abstract 9: Peak Width of Skeletonized Mean Diffusivity and Cognition in Cerebral Amyloid Angiopathy

Background: We hypothesized that Peak Width of Skeletonized Mean Diffusivity (PSMD), an automated marker of cerebral microangiopathy representing microstructural disruption of white matter (WM), would be increased in patients with cerebral amyloid angiopathy (CAA) compared to healthy controls (HCs) and increased PSMD would be associated with lower processing speed scores (PSSs) in patients with CAA.

Methods: Seventy-two nondemented probable CAA patients and 23 HCs prospectively underwent high-resolution brain MRIs and cognitive tests. PSMD scores were quantified from a probabilistic skeleton of the WM tracts as previously validated (http://www.psmd-marker.com). In subjects with intracerebral hemorrhage (ICH, n=27), ICH regions were masked and removed from the PSMD pipeline. The analyses were repeated in the non-ICH hemisphere. Raw scores of Trail Making Test-B and Symbol Substitution Test were transformed into standardized z -scores and averaged to obtain PSSs.

Results: The mean age (p=0.366) and sex (p=0.811) were similar between CAA patients and HCs. PSMD was higher in the CAA group [(3.95±0.9) х 10 –4 mm 2 /s] compared to HCs [(3.32±0.6) х 10 –4 mm 2 /s] (p=0.003). This association remained significant in a linear regression model corrected for age and sex (β=0.700, 95%CI 0.3-1, p=0.001). Within the CAA cohort, higher PSMD was associated with higher WM hyperintensity volume in a multiple regression model adjusted for all relevant variables (β=0.890, 95%CI 0.7-1, p<0.001). In a regression model corrected for age, sex, years of education and presence of ICH, a lower PSS was independently associated with increased PSMD (β=-0.405, 95%CI {-0.6}-{-0.2}, p<0.001). These results did not change when the non-ICH hemisphere was used for PSMD processing.

Conclusion: PSMD is increased in CAA and is associated with worse PSSs supporting the view that disruption of white matter has a significant role in cognitive impairment in CAA.

Abstract P442: The Association of Amyloid and Tau Burden With Centrum Semiovale Perivascular Spaces in Cerebral Amyloid Angiopathy

Background: The mechanisms linking cerebral amyloid angiopathy (CAA) to enlarged perivascular spaces in centrum semiovale (CSO-EPVS) and whether other Alzheimer’s Disease (AD) pathologies might affect CSO-EPVS are unclear. We hypothesized that amyloid but not tau load would independently correlate with CSO-EPVS in CAA.

Methods: Fifty prospectively enrolled nondemented probable CAA patients underwent high-resolution structural MRI, Pittsburgh compound B (PiB, for amyloid), and 18 F-flortaucipir (FTP, for tau) PET imaging. Microbleeds (all lobar, LMB) were counted and white matter hyperintensity volume (WMH) was quantified. CSO-EPVS were counted on T 2 -MRI sequence and graded using a previously validated scale (range 0-4). A multivariate ordinal regression model was used to assess the independent associations between CSO-EPVS and mean cortical amyloid as well as tau deposition, after adjusting for relevant covariates.

Results: Patients had a mean age of 69.3±7.2. Age, sex, presence of hypertension, intracerebral hemorrhage (ICH), LMB counts, and WMH were not associated with CSO-EPVS grades (p>0.2 for all comparisons). Higher PiB uptake significantly correlated with increased CSO-EPVS (rho=0.45, p=0.001). Higher FTP showed a trend for correlation with CSO-EPVS (rho=0.26, p=0.069). In an ordinal regression model with CSO-EPVS grade as the dependent variable and both amyloid and tau levels included as predictors along with covariates presented above, the association of CSO-EPVS remained significant with higher PiB uptake (β=3.97, 95%CI 1.1-6.8, p=0.007) but not with FTP uptake (p=0.167).

Conclusion: Results of this study suggest that CSO-EPVS is independently associated with amyloid but not with tau deposition in CAA. CSO-EPVS was not associated with age or classical vascular risk factors or presence of ICH. Our results support the view that vascular amyloid but not other AD pathologies such as tau might contribute to EPVS in patients with CAA.

Abstract P409: Cerebellar Atrophy and Its Clinical Implications in Cerebral Amyloid Angiopathy

Background: Recent data show that cerebral amyloid angiopathy (CAA) might cause hemorrhagic lesions in cerebellar cortex as well as cerebral atrophy. However, the potential effect of CAA on cerebellar tissue loss and its clinical implications have not been investigated.

Methods: We compared cerebellar volumes in 70 nondemented patients with probable CAA to 70 age-matched healthy controls (HC) and 70 age-matched Alzheimer’s disease (AD) patients. Volumetric analyses including cerebellar cortical volume (pCbll-CV), cerebellar subcortical volume (pCbll-ScV), cerebral white matter volume (pWMV), and cerebral white matter hyperintensity volume (pWMH) were calculated as percent of total intracranial volume. Gait velocity (meters/seconds) was used to investigate the potential effect of cerebellar tissue loss on gait function.

Results: Patients with CAA had significantly lower pCbll-ScV and pCbll-CV compared to HC (1.49%±0.17 vs 1.71%±0.23, p<0.001 and 6.03%±0.50 vs 6.23%±0.56, p<0.027 respectively). When compared to AD, pCbll-ScV but not pCbll-CV was significantly lower in CAA (1.49%±0.17 vs 1.670.24, p<0.001). Diagnosis of CAA was independently associated with lower pCbll-ScV in a general linear model adjusting for age, sex and presence of hypertension when compared to both HCs and patients with AD (p<0.0001 for all associations, after Bonferroni correction for multiple comparisons). Lower pCbll-ScV was associated with lower gait velocity score in univariate and multivariate analysis adjusted for relevant variables (adjusted β=0.826, 95%CI 0.357-1.295, p=0.001).

Conclusion: Patients with CAA show cerebellar atrophy; predominantly in the subcortical cerebellum when compared to both HC and AD patients. Cerebellar tissue loss independently correlated with worse gait function in CAA patients. Overall, this study supports the view that CAA causes cerebellar injury which might mediate gait disturbance in patients with CAA.

The role of biomarkers and neuroimaging in ischemic/hemorrhagic risk assessment for cardiovascular/cerebrovascular disease prevention

Stroke prevention in patients with atrial fibrillation is arguably one of the fastest developing areas in preventive medicine. The increasing use of direct oral anticoagulants and nonpharmacologic methods such as left atrial appendage closure for stroke prevention in these patients has increased clinicians' options for optimal care. Platelet antiaggregants are also commonly used in other ischemic cardiovascular and or cerebrovascular conditions. Long term use of oral anticoagulants for atrial fibrillation is associated with elevated risks of major bleeds including especially brain hemorrhages, which are known to have extremely poor outcomes. Neuroimaging and other biomarkers have been validated to stratify brain hemorrhage risk among older adults. A thorough understanding of these biomarkers is essential for selection of appropriate anticoagulant or left atrial appendage closure for stroke prevention in patients with atrial fibrillation. This article will address advances in the stratification of ischemic and hemorrhagic stroke risk among patients with atrial fibrillation and other conditions.

Abstract 16: Functional Magnetic Resonance Imaging as a Predictor of Cognitive Impairment in Cerebral Amyloid Angiopathy

Background: Cerebral Amyloid Angiopathy (CAA) emerged as an important contributor to cognitive impairment (CI) in elderly. Multiple lines of evidence suggest the presence of vascular dysfunction in CAA but its relationship to CI has not been tested. We hypothesized that the degree of vascular dysfunction identified by functional magnetic resonance imaging (fMRI) is a predictor of subsequent development of CI in patients with CAA.

Methods: Thirty nondemented probable CAA patients diagnosed with Boston criteria were prospectively enrolled. They underwent high-resolution structural MRI and fMRI at baseline and cognitive assessment both at baseline and follow up. Structural MRI markers (microbleed counts, superficial siderosis, enlarged perivascular spaces, cortical microinfarcts) and FreeSurfer based volumetric analyses (cortical thickness, white matter hyperintensity volume) were obtained. An fMRI measure of vascular reactivity to visual stimulation, time-to-peak [TTP] of blood oxygen level-dependent [BOLD] response, was the main physiologic marker of interest. Main outcome measure was the development of CI defined based on structured cognitive assessments.

Results: Patients had a mean age of 69.1±7.6 years. During a median follow-up of 23 months, 13 patients (43.3%) developed CI. Patients who developed CI did not differ from the patients without CI in terms of age, sex, risk factors and structural MRI markers (all p>0.2). Patients with CI trended towards fewer years of education (16±2.8 years vs 18±2.8 years, p=0.069). Baseline TTP of BOLD response was significantly higher in patients with incident CI as compared to patients without CI (12.7 ± 5.8 vs 7.8 ± 2.9, p=0.005). In a cox regression analysis, higher TTP was independently associated with future CI risk, after adjusting for age, sex, WMH volumes and education years (hazard ratio: 1.23; 95% CI: 1.06-1.42; p=0.006).

Conclusion: The severity of baseline vascular dysfunction is associated with future CI in CAA. Unlike markers of parenchymal injury that are typically irreversible, vascular dysfunction might be reversible making our findings potentially relevant to future therapeutic development efforts.

Abstract 19: Default Mode Network Alterations in Cerebral Amyloid Angiopathy: A Resting State FMRI Study

Introduction: Cerebral amyloid angiopathy (CAA) is an established cause of intracerebral hemorrhage and vascular dysfunction leading to ischemia. Functional connectivity analysis using MRI is becoming an important tool to analyze the brain activity during resting state, the default mode network (DMN) representing the prototypical set of connections. As CAA pathology has a posterior predominance, we sought to characterize the functional connectivity of the posterior DMN at resting state in patients with CAA.

Methods: Patients with probable CAA diagnosed using Boston Criteria and healthy controls (HC) were prospectively enrolled and received high resolution 3T MRI scans including dedicated resting-state fMRI sequences. Functional seed-to-seed analyses were done using the default processing pipeline in the CONN Toolbox. Correlation maps between the established DMN and specific regions of the posterior DMN, the precuneus and posterior cingulate, were averaged within groups and compared in an ANCOVA model.

Results: Study participants consisted of 60 patients with probable CAA and 20 healthy controls [aged 69 ± 7.5 vs 72.3 ± 8 years, P = 0.108]. Seed-to-seed analysis revealed a significantly lower strength of DMN connectivity in CAA when compared to controls in the precuneus [ P = 0.009] and posterior cingulate [ P = 0.003] adjusted for age and sex (Fig 1).

Conclusion: Patients with CAA exhibited significant loss of connectivity in the posterior regions of the DMN when compared to controls. The precuneus and posterior cingulate are core regions of the DMN with reportedly high metabolic rates at rest. Disruption of these posterior DMN regions might occur due to vascular amyloid pathology that shows a predominantly posterior distribution.

Effects of maternal natural (RRR alpha-tocopherol acetate) or synthetic (all-rac alpha-tocopherol acetate) vitamin E supplementation on suckling calf performance, colostrum immunoglobulin G, and immune function

The objective of this study was to determine the effects of maternally supplemented natural- or synthetic-source vitamin E on suckling calf performance and immune response. In a 2-yr study, one hundred fifty-two 2- and 3-yr-old, spring-calving, Angus-cross beef cows were blocked by age, BW, and BCS into 1 of 3 isocaloric, corn-based dietary supplements containing 1) no additional vitamin E (CON), 2) 1,000 IU/d of synthetic-source vitamin E (SYN), or 3) 1,000 IU/d of natural-source vitamin E (NAT). Maternal supplementation began approximately 6 wk prepartum and continued until the breeding season. Colostrum from cows and blood from calves was collected 24 h postpartum for analysis of IgG concentration as an indicator of passive transfer and circulating alpha-tocopherol concentration. At 19 d of age, blood was collected from calves to determine the expression of CD14 and CD18 molecules on leukocytes. At 21 and 35 d of age, humoral immune response was measured by a subcutaneous injection, in the neck, with ovalbumin (20 mg; OVA) and blood samples collected weekly until d 63 of age to determine antibodies produced against OVA. At d 63 of age, calves were administered an intradermal injection of OVA (1 mg) in the neck to assess cell-mediated immunity, which was determined on d 65 of age by measuring nodule size with calipers. Circulating alpha-tocopherol concentrations were increased at both 24 h (P = 0.001) and at the day of initial OVA challenge (P < 0.001) in SYN and NAT compared with CON calves. No differences were detected (P > 0.05) for calf birth BW, ADG, or weaning BW. There were no differences (P > 0.05) in calf serum total IgG or cow colostrum total IgG at 24 h or presence of CD14 and CD18 receptors at d 19 of age. The NAT calves had a greater antigen response to OVA at d 63 than SYN calves (P = 0.01; treatment x day interaction). As an indicator of cell-mediated immunity to OVA, nodule size at 65 d of age was not affected (P = 0.92) by maternal dietary supplementation. In conclusion, calves suckling cows supplemented with natural- and synthetic-source vitamin E had increased circulating concentrations of alpha-tocopherol at 24 h, which appeared to continue throughout maternal supplementation; however, calf immune function and performance were not affected.

Angiotensin-converting enzyme inhibition attenuates the progression of rat hepatic fibrosis

BACKGROUND AND AIMS

There is a significant relationship between inheritance of high transforming growth factor (TGF)-beta1 and angiotensinogen-producing genotypes and the development of progressive hepatic fibrosis in patients with chronic hepatitis C. In cardiac and renal fibrosis, TGF-beta1 production may be enhanced by angiotensin II, the principal effector molecule of the renin-angiotensin system. The aim of the present study was to determine the effects of the angiotensin-converting enzyme inhibitor, captopril, on the progression of hepatic fibrosis in the rat bile duct ligation model.

METHODS

Rats were treated with captopril (100 mg. kg(-1). day(-1)) commencing 1 or 2 weeks after bile duct ligation. Animals with bile duct ligation only and sham-operated animals served as controls. Four weeks after bile duct ligation, indices of fibrosis were assessed.

RESULTS

Captopril treatment significantly reduced hepatic hydroxyproline levels, mean fibrosis score, steady state messenger RNA levels of TGF-beta1 and procollagen alpha1(I), and matrix metalloproteinase 2 and 9 activity.

CONCLUSIONS

Captopril significantly attenuates the progression of hepatic fibrosis in the rat bile duct ligation model, and its effectiveness should be studied in human chronic liver diseases associated with progressive fibrosis.

Cell block cytology. Improved preparation and its efficacy in diagnostic cytology

Cell blocks prepared from residual tissue fluids and fine-needle aspirations can be useful adjuncts to smears for establishing a more definitive cytopathologic diagnosis. They can be particularly useful for categorization of tumors that otherwise may not be possible from smears themselves. A modified cell block technique using an improvised ethanol formalin fixative (Nathan alcohol formalin substitute) followed by a simple paraffin processing schedule is described. This improved preparation offers excellent cytomorphologic features corresponding closely to cells in Papanicolaou-stained smears and ensures optimal preservation of histochemical and immunocytochemical properties. The technique is simple and reproducible and uses routine safe laboratory chemicals. The efficacy of cell blocks also is discussed.

Psychological and demographic predictors of successful weight loss following silastic ring vertical stapled gastroplasty

To identify psychological factors involved in obesity 45 individuals (40 women and 5 men), ranging in age from 21 to 54 years (M age = 41 yr.), who were candidates for silastic ring vertical stapled gastroplasty were assessed on the Millon Behavioral Health Inventory and the Millon Multiaxial Clinical Inventory-III. In addition, a number of demographic variables such as education, marital status, and age of onset of obesity were considered. Analysis indicated that significant predictors of weight loss at a 6-mo. postoperative assessment include age of onset of obesity and scores on the Schizoid scale of the Millon-III. These findings may be of assistance in identifying personality variables associated with changes in weight if replicated in a larger sample.

Undifferentiated (embryonal) sarcoma of the liver. Pathologic findings and long-term survival after complete surgical resection

Undifferentiated (embryonal) sarcoma of liver is a rare tumor with a reputed poor prognosis. Four patients with this tumor are reported, of whom three were alive without recurrence 1.5, 2.5, and 12 years after initial complete surgical resection, and two of whom received no adjuvant therapy. The fourth patient, in whom complete surgical resection of tumor was not achieved, died with recurrent tumor at 13 months. The latter tumor differed histologically and consisted mainly of closely packed smaller undifferentiated cells with a higher mitotic and apoptotic rate. Eosinophilic globules, characteristic of embryonal sarcoma, were found in some cases to contain condensed nuclear chromatin, evidence of origin from tumor cells dying by apoptosis. One tumor mainly contained large cysts lined by biliary-type epithelium; this suggested an origin from a multipotent precursor cell able to differentiate along both stromal and epithelial lines.

Computer-assisted work station timing analysis of instrument labor efficiency

Labor use ratings assigned to instruments by the Workload Recording Method (WRM) do not change with batch size or walk-away time use. The authors evaluated the effect of both on the labor use of the analyzers Paramax B6100 (Baxter Paramax, Irvine, CA) and Ektachem 700 (Eastman Kodak, Rochester, NY) by timing all worked and walk-away intervals on both instruments. Extrapolation of the data to a workload of slightly more than 1.1 million tests showed that reapportionment of tests to various batch sizes caused Paramax-Ektachem labor cost differences to fluctuate between $37,254 and $34,995. When the minimum usable walk-away interval length was varied from 1 to 20 minutes, Ektachem savings over Paramax increased from $8,700 to $61,400. The WRM predicted a constant $29,050 labor cost advantage for Ektachem over Paramax. If other instruments show similar labor use characteristics with respect to batch size and walk-away utility, laboratory managers who do not consider these factors may fail to select the most cost-effective instruments for their laboratories.

Characterization of murine macrophage Fc receptor-dependent phagocytosis and antibody-dependent cellular cytotoxicity during in vitro culture with interferons-gamma, alpha/beta and/or fetal bovine serum

Resident and oil-elicited inflammatory peritoneal macrophages (PM phi) from competent C3HeB/FeJ and genetically deficient C3H/HeJ mice were characterized for their Fc receptor (FcR)-dependent binding, phagocytic and ADCC functions during in vitro differentiation under the influence of mouse recombinant interferon-gamma (rIFN-gamma), interferon-alpha/beta (IFN-alpha/beta) fetal bovine serum (FBS), or in serum-free medium. Freshly cultured resident PM phi from C3HeB/FeJ mice had low levels of FcR-mediated phagocytosis in response to mouse monoclonal IgG gamma 2a, IgG gamma 2b or IgG gamma 1, opsonized sheep erythrocytes as compared to oil-elicited inflammatory PM phi from the same strain. Resident PM phi were uniformly upregulated in their FcR-dependent phagocytosis after 24-48 h in vitro culture with FBS to levels approximating that of freshly cultured inflammatory PM phi which were also further upregulated after 24 h in vitro culture with FBS. Both resident and inflammatory PM phi were upregulated largely by an autostimulatory process in that they increased their FcR-mediated phagocytosis in serum-free RPMI-1640 medium without the addition of rIFN-gamma or IFN-alpha/beta, although FBS further augmented FcR upregulation. A synergistic effect of FBS and rIFN-gamma was required for total reconstitution of FcR-mediated phagocytosis of FcR-incompetent C3H/HeJ inflammatory PM phi in that FBS or rIFN-gamma alone only partially reconstituted FcR function, whereas in combination full reconstitution occurred. Thus, macrophages from competent C3HeB/FeJ mice were upregulated in their FcR-mediated functions largely by an autostimulatory process, presumably dependent on endogenous of IFN-beta, whereas, genetically-deficient C3H/HeJ macrophages required exogenous rIFN-gamma in combination with fetal bovine serum for synergistic reconstitution of FcR functions. The uniform upregulation of FcR-dependent effector functions in vitro appears to provide an efficient system for enhanced immune function during differentiation which may be applicable to in vivo situations.

A new tool for peptide separation

A family of reagents has been developed (Pep-Seps) which provide separations of peptides based upon the presence or absence of a single type of amino acid. This separation is achieved through a reversible, covalent attachment of the peptide to the Pep-Seps reagents. Pep-Seps provide a more specific separation than most forms of HPLC and may be used to complement HPLC in peptide separations and isolations. Several specific applications will be discussed.

Photometric assays for FcRI-dependent binding, phagocytosis, and antibody-dependent cellular cytotoxicity mediated by monomeric IgG gamma 2a in murine peritoneal macrophages

Mouse peritoneal macrophages possess distinct Fc receptors (FcR) for binding the various murine IgG isotypes. FcRI binds monomeric IgG gamma 2a, but not monomeric IgG gamma 2b or IgG gamma 1 with high affinity at 4 degrees C and is sensitive to trypsin degradation. We have assessed the functional consequences of the cytophilic binding at 4 degrees C of monomeric IgG gamma 2a to FcRI of mouse peritoneal macrophages using newly developed photometric microassays for quantification of binding, phagocytosis, and antibody dependent cellular cytotoxicity (ADCC) of post-opsonized sheep red blood cell (SRBC) targets. Dose-dependent binding specificity of monomeric IgG gamma 2a, but not IgG gamma 2b or IgG gamma 1 to FcRI of oil-elicited mouse peritoneal macrophages at 4 degrees C for 2 h was confirmed to display typical saturation kinetics both by the photometric assay and by a cellular enzyme-linked immunosorbent assay (CELISA). Binding of monomeric IgG gamma 2a to macrophage FcRI promoted highly efficient phagocytosis of opsonized SRBC in that most cells that were bound were also rapidly internalized by the phagocytic process during a 1 h incubation at 37 degrees C. Upregulation of FcRI-dependent binding and phagocytosis occurred during 24-48 h in vitro culture of macrophages as shown both by the photometric assays and CELISA. Trypsin treatment of macrophages abrogated FcRI-dependent binding and phagocytosis by monomeric IgG gamma 2a, but had little effect on FcRII-dependent functions. Cytophilic binding of monomeric IgG gamma 2a to FcRI failed to trigger ADCC activation. Thus functional characterization of macrophage FcRI-dependent effector functions confirmed the fidelity of binding specificity of monomeric IgG gamma 2a to a trypsin degradable receptor which mediates highly efficient phagocytosis but fails to initiate the signal for ADCC activation. It appears that passively bound immune monomeric IgG gamma 2a could provide an efficient mechanism by macrophages in vivo for FcRI-dependent immune clearance of soluble or particulate cellular antigens without elicitation of potentially harmful cytolytic factors associated with ADCC activation.

Methylthiohydantoin amino acids: chromatographic separation and comparison to phenylthiohydantoin amino acids

Most phenylthiohydantoin (PTH) amino acids and most methylthiohydantoin (MTH) amino acids may be separated from one another by thin-layer chromatography (TLC) using the same sequential development technique with the same two solvents. Similarly, a single solvent system may be used in high-performance liquid chromatography (HPLC) to separate most PTH-amino acids and most MTH-amino acids. When both TLC and HPLC separations are performed on a sample, all MTH-and PTH-amino acids can be uniquely identified. Since many solid-phase protein sequencing techniques generate both MTH-and PTH-amino acids, these analytical systems simplify identification of the amino acid derivatives. Although the chromatographic properties of MTH-and PTH-amino acids are similar, they are not identical (contrary to a previous report).

Determination of the amino acid sequence of troponon C from rabbit skeletal muscle

The complete amino acid sequence of rabbit skeletal muscle troponin C (TnC) was determined from studies on overlapping peptides isolated from cyanogen bromide and tryptic digests. TnC was found to be a single polypeptide chain of 159 amino acid residues, including 2 residues of tyrosine and 1 each of cysteine, histidine, and proline. The amino end is acetylated, the calculated net charge at pH 7.0 is -29, and the calculated molecular weight is 17,965. There was no evidence for heterogeneity in the sequence. The previously proposed four apparent Ca2+ binding sites are located at residues 27 to 38, 63 to 74, 103 to 114, and 139 to 150.

Bias against genetic hypotheses in adoption studies

Genetic factors are implicated in the cause of psychopathological disorders whenever the incidence of disorder is greater among the adopted-away offspring of affected parents than among those of control (unaffected) parents. The lack of information about most parents who give their children up for adoption could result in the inclusion of a substantial number of high-risk parents in the control groups. This could bias an adoption study against a genetic hypothesis. The Minnesota Multiphasic Personality inventory scores of two groups of pregnant unwed mothers were compared to those of two other groups: married pregnant women and 18-year-old women. Comparisons disclosed that the unwed mothers had significant elevations on five to the nine clinical scales. Elevations on psychopathic deviancy and schizophrenia were particularly substantial. These results indicate a requirement to select control group parents who are representative of the general population.