Peak Width of Skeletonized Mean Diffusivity as Neuroimaging Biomarker in Cerebral Amyloid Angiopathy

BACKGROUND AND PURPOSE

Whole-brain network connectivity has been shown to be a useful biomarker of cerebral amyloid angiopathy and related cognitive impairment. We evaluated an automated DTI-based method, peak width of skeletonized mean diffusivity, in cerebral amyloid angiopathy, together with its association with conventional MRI markers and cognitive functions.

MATERIALS AND METHODS

We included 24 subjects (mean age, 74.7 [SD, 6.0] years) with probable cerebral amyloid angiopathy and mild cognitive impairment and 62 patients with MCI not attributable to cerebral amyloid angiopathy (non-cerebral amyloid angiopathy-mild cognitive impairment). We compared peak width of skeletonized mean diffusivity between subjects with cerebral amyloid angiopathy-mild cognitive impairment and non-cerebral amyloid angiopathy-mild cognitive impairment and explored its associations with cognitive functions and conventional markers of cerebral small-vessel disease, using linear regression models.

RESULTS

Subjects with Cerebral amyloid angiopathy-mild cognitive impairment showed increased peak width of skeletonized mean diffusivity in comparison to those with non-cerebral amyloid angiopathy-mild cognitive impairment (P < .001). Peak width of skeletonized mean diffusivity values were correlated with the volume of white matter hyperintensities in both groups. Higher peak width of skeletonized mean diffusivity was associated with worse performance in processing speed among patients with cerebral amyloid angiopathy, after adjusting for other MRI markers of cerebral small vessel disease. The peak width of skeletonized mean diffusivity did not correlate with cognitive functions among those with non-cerebral amyloid angiopathy-mild cognitive impairment.

CONCLUSIONS

Peak width of skeletonized mean diffusivity is altered in cerebral amyloid angiopathy and is associated with performance in processing speed. This DTI-based method may reflect the degree of white matter structural disruption in cerebral amyloid angiopathy and could be a useful biomarker for cognition in this population.

Apolipoprotein D: a potential biomarker for cerebral amyloid angiopathy

AIMS

We investigated the potential of apolipoprotein D (apoD) as cerebrospinal fluid (CSF) biomarker for cerebral amyloid angiopathy (CAA) after confirmation of its association with CAA pathology in human brain tissue.

METHODS

The association of apoD with CAA pathology was analysed in human occipital lobe tissue of CAA (n = 9), Alzheimer's disease (AD) (n = 11) and healthy control cases (n = 11). ApoD levels were quantified in an age- and sex-matched CSF cohort of CAA patients (n = 31), AD patients (n = 27) and non-neurological controls (n = 67). The effects of confounding factors (age, sex, serum levels) on apoD levels were studied using CSF of non-neurological controls (age range 16-85 years), and paired CSF and serum samples.

RESULTS

ApoD was strongly associated with amyloid deposits in vessels, but not with parenchymal plaques in human brain tissue. CSF apoD levels correlated with age and were higher in men than women in subjects >50 years. The apoD CSF/serum ratio correlated with the albumin ratio. When controlling for confounding factors, CSF apoD levels were significantly lower in CAA patients compared with controls and compared with AD patients (P = 0.0008).

CONCLUSIONS

Our data show that apoD is specifically associated with CAA pathology and may be a CSF biomarker for CAA, but clinical application is complicated due to dependency on age, sex and blood-CSF barrier integrity. Well-controlled follow-up studies are required to determine whether apoD can be used as reliable biomarker for CAA.

Effect of CTA Tube Current on Spot Sign Detection and Accuracy for Prediction of Intracerebral Hemorrhage Expansion

BACKGROUND AND PURPOSE

Reduction of CT tube current is an effective strategy to minimize radiation load. However, tube current is also a major determinant of image quality. We investigated the impact of CTA tube current on spot sign detection and diagnostic performance for intracerebral hemorrhage expansion.

MATERIALS AND METHODS

We retrospectively analyzed a prospectively collected cohort of consecutive patients with primary intracerebral hemorrhage from January 2001 to April 2015 who underwent CTA. The study population was divided into 2 groups according to the median CTA tube current level: low current (<350 mA) and high current (≥350 mA). CTA first-pass readings for spot sign presence were independently analyzed by 2 readers. Baseline and follow-up hematoma volumes were assessed by semiautomated computer-assisted volumetric analysis. Sensitivity, specificity, positive and negative predictive values, and accuracy of spot sign in predicting hematoma expansion were calculated.

RESULTS

This study included 709 patients (288 and 421 in the low- and high-current groups, respectively). A higher proportion of low-current scans identified at least 1 spot sign (20.8% versus 14.7%, P = .034), but hematoma expansion frequency was similar in the 2 groups (18.4% versus 16.2%, P = .434). Sensitivity and positive and negative predictive values were not significantly different between the 2 groups. Conversely, high-current scans showed superior specificity (91% versus 84%, P = .015) and overall accuracy (84% versus 77%, P = .038).

CONCLUSIONS

CTA obtained at high levels of tube current showed better diagnostic accuracy for prediction of hematoma expansion by using spot sign. These findings may have implications for future studies using the CTA spot sign to predict hematoma expansion for clinical trials.

Decoupling of structural and functional brain connectivity in older adults with white matter hyperintensities

Age-related impairments in the default network (DN) have been related to disruptions in connecting white matter tracts. We hypothesized that the local correlation between DN structural and functional connectivity is negatively affected in the presence of global white matter injury. In 125 clinically normal older adults, we tested whether the relationship between structural connectivity (via diffusion imaging tractography) and functional connectivity (via resting-state functional MRI) of the posterior cingulate cortex (PCC) and medial prefrontal frontal cortex (MPFC) of the DN was altered in the presence of white matter hyperintensities (WMH). A significant correlation was observed between microstructural properties of the cingulum bundle and MPFC-PCC functional connectivity in individuals with low WMH load, but not with high WMH load. No correlation was observed between PCC-MPFC functional connectivity and microstructure of the inferior longitudinal fasciculus, a tract not passing through the PCC or MPFC. Decoupling of connectivity, measured as the absolute difference between structural and functional connectivity, in the high WMH group was related to poorer executive functioning and memory performance. These results suggest that such decoupling may reflect reorganization of functional networks in response to global white matter pathology and may provide an early marker of clinically relevant network alterations.

SCORE-IT: the Spot Sign score in restricting ICH growth─an Atach-II ancillary study

INTRODUCTION

The ATACH-II trial is designed to evaluate whether intensive blood pressure reduction can reduce hematoma growth and improve outcome. However, it is difficult to determine, at presentation, which patients are at highest risk of ongoing bleeding, and will receive the most clinical benefit from blood pressure therapy. It may be that improved predictive markers will lead to efficient, personalized selection of optimal therapy. We hypothesize that specific imaging findings on CT angiography (CTA) and MRI will mark those patients who receive the most benefit from intensive blood pressure reduction.

METHODS

Many patients enrolled in ATACH-II will undergo CTA and/or MRI as part of routine clinical care. We will perform a blinded analysis of these images. For CTA, we will determine the presence of contrast pooling (also termed contrast extravasation or the "Spot Sign"). In addition, we will calculate a Spot Sign Score, a score that includes number of Spot Signs, diameter, and contrast density. For MRI, we will focus on the presence, number, and location of cerebral microbleeds (CMBs) on sensitive T2*-weighted MRI sequences.

RESULTS

We will test the hypothesis that patients with a Spot Sign will receive clinical benefit from intensive blood pressure reduction. In addition, we will determine whether patients with the highest Spot Sign Scores receive the most benefit from intensive blood pressure reduction. Finally, we will determine whether the absence of CMBs marks those at higher risk for hematoma expansion, and therefore more likely to benefit from treatment.

CONCLUSION

This ancillary study offers the tremendous opportunity to determine whether imaging findings can risk stratify ICH patients for acute therapies aimed at limiting hematoma growth.

Clinical outcomes of total wrist arthroplasty

PURPOSE

Current indications for total wrist arthroplasty include patients with symptomatic end stage posttraumatic wrist arthritis, rheumatoid arthritis, and Kienböck disease, as an alternative to wrist arthrodesis. Arthroplasty may have advantage over arthrodesis because of the ability to retain motion. The purpose of this study was to evaluate the short-term clinical outcomes and complications of the Maestro Total Wrist System.

METHODS

We report the results of a retrospective review of 23 total wrist prostheses implanted in 22 patients. We administered the visual analog pain scale and Mayo wrist and Disabilities of the Arm, Shoulder, and Hand questionnaires. We reviewed wrist motion, grip strength, radiographs, and complications.

RESULTS

At a mean follow-up of 28 months (range, 4-55 mo), the Disabilities of the Arm, Shoulder, and Hand score and Mayo wrist score were 31 and 54, respectively. Mean pain scores improved from 8.0 to 2.2. The mean wrist flexion-extension arc was 90°. Radiographs revealed no evidence of prosthetic loosening. Grip strength averaged 60% of the strength of the opposite hand. Complications occurred in 7 of 23 patients. One failure occurred as a result of deep infection in a patient with prior intercarpal fusion, and was successfully converted to a wrist fusion.

CONCLUSIONS

Total wrist arthroplasty performed for pancarpal arthritis as an alternative to wrist arthrodesis can yield successful outcomes with low short-term failure rates.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic IV.

Genetic variation at CR1 increases risk of cerebral amyloid angiopathy

OBJECTIVE

Accumulated evidence suggests that a variant within the CR1 gene (single nucleotide polymorphism rs6656401), known to increase risk for Alzheimer disease (AD), influences β-amyloid (Aβ) deposition in brain tissue. Given the biologic overlap between AD and cerebral amyloid angiopathy (CAA), a leading cause of intracerebral hemorrhage (ICH) in elderly individuals, we investigated whether rs6656401 increases the risk of CAA-related ICH and influences vascular Aβ deposition.

METHODS

We performed a case-control genetic association study of 89 individuals with CAA-related ICH and 280 individuals with ICH unrelated to CAA and compared them with 324 ICH-free control subjects. We also investigated the effect of rs6656401 on risk of recurrent CAA-ICH in a prospective longitudinal cohort of ICH survivors. Finally, association with severity of histopathologic CAA was investigated in 544 autopsy specimens from 2 longitudinal studies of aging.

RESULTS

rs6656401 was associated with CAA-ICH (odds ratio [OR] = 1.61, 95% confidence interval [CI] 1.19-2.17, p = 8.0 × 10(-4)) as well as with risk of recurrent CAA-ICH (hazard ratio = 1.35, 95% CI 1.04-1.76, p = 0.024). Genotype at rs6656401 was also associated with severity of CAA pathology at autopsy (OR = 1.34, 95% CI 1.05-1.71, p = 0.009). Adjustment for parenchymal amyloid burden did not cancel this effect, suggesting that, despite the correlation between parenchymal and vascular amyloid pathology, CR1 acts independently on both processes, thus increasing risk of both AD and CAA.

CONCLUSION

The CR1 variant rs6656401 influences risk and recurrence of CAA-ICH, as well as the severity of vascular amyloid deposition.

Warfarin-related intraventricular hemorrhage: imaging and outcome

OBJECTIVE

Oral anticoagulation therapy (OAT) with warfarin increases mortality and disability after intracerebral hemorrhage (ICH), the result of increased ICH volume and risk of hematoma expansion. We investigated whether OAT also influences risk of development of intraventricular hemorrhage (IVH), the volume of IVH and IVH expansion, and whether IVH is a substantive mediator of the overall effect of OAT on ICH outcome.

METHODS

We performed a retrospective analysis of a prospectively collected single-center cohort of 1,879 consecutive ICH cases (796 lobar, 865 deep, 153 cerebellar, 15 multiple location, 50 primary IVH) from 1999 to 2009. ICH and IVH volumes at presentation, as well as hematoma expansion (>33% or >6 mL increase) and IVH expansion (>2 mL increase), were determined using established semiautomated methods. Outcome was assessed at 90 days using either the modified Rankin Scale or Glasgow Outcome Scale.

RESULTS

Warfarin use was associated with IVH risk, IVH volume at presentation, and IVH expansion in both lobar and deep ICH (all p < 0.05) in a dose-response relationship with international normalized ratio. Warfarin was associated with poor outcome in both lobar and deep ICH (p < 0.01), and >95% of this effect was accounted for by baseline ICH and IVH volumes, as well as ICH and IVH expansion.

CONCLUSION

Warfarin increases IVH volume and risk of IVH expansion in lobar and deep ICH. These findings (along with effects on ICH volume and expansion) likely represent the mechanisms by which anticoagulation worsens ICH functional outcome.

Cerebral microbleeds and cognitive functioning in the PROSPER study

OBJECTIVES

Cerebral microbleeds (MBs) are an important indicator of cerebral small-vessel disease, and their prevalence increases with increasing age. Little is known about the functional consequences of MBs in the aging population. In this study we investigated whether the presence and location of MBs are associated with cognition in the PROSPER study.

METHODS

For 439 subjects the number and location (cortico-subcortical, deep white matter, basal ganglia, and infratentorial) of the MBs was recorded. Difference in cognitive performance between subjects with and without MBs was calculated by entering the variables sex, age, white matter hyperintensity volume, infarction, and MBs in a linear mixed model. Differences in cognition between subjects with and without one or more MBs at different anatomic locations were assessed using the same model.

RESULTS

We found that after correction for sex, age, white matter hyperintensity volume, and infarction, subjects with infratentorial MBs had a significantly lower score on the Immediate Picture-Word Learning test, Delayed Picture-Word Learning, and Instrumental Activities of Daily Living.

CONCLUSIONS

Our data demonstrate that in elderly individuals at increased vascular risk, infratentorial MBs are associated with loss in cognitive functioning.

Correlations between MRI white matter lesion location and executive function and episodic memory

OBJECTIVES

MRI white matter hyperintensity (WMH) volume is associated with cognitive impairment. We hypothesized that specific loci of WMH would correlate with cognition even after accounting for total WMH volume.

METHODS

Subjects were identified from a prospective community-based study: 40 had normal cognition, 94 had mild impairment (defined here as a Clinical Dementia Rating [CDR] score of 0.5 without dementia), and 11 had mild Alzheimer's dementia. Factor analysis of a 22-item neuropsychological battery yielded 4 factors (episodic memory, executive function, spatial skills, and general knowledge). MRI WMH segmentation and analysis was performed using FreeSurfer software.

RESULTS

Higher WMH volume was independently associated with lower executive function and episodic memory factor scores. Voxel-based general linear models showed loci where WMH was strongly inversely associated with specific cognitive factor scores (p < 0.001), controlling for age, education, sex, APOE genotype, and total WMH volume. For episodic memory, clusters were observed in bilateral temporal-occipital and right parietal periventricular white matter, and the left anterior limb of the internal capsule. For executive function, clusters were observed in bilateral inferior frontal white matter, bilateral temporal-occipital and right parietal periventricular white matter, and the anterior limb of the internal capsule bilaterally.

CONCLUSIONS

Specific WMH loci are closely associated with executive function and episodic memory, independent of total WMH volume. The anatomic locations suggest that WMH may cause cognitive impairment by affecting connections between cortex and subcortical structures, including the thalamus and striatum, or connections between the occipital lobe and frontal or parietal lobes.

Statin use and outcome after intracerebral hemorrhage: case-control study and meta-analysis

OBJECTIVES

Intracerebral hemorrhage (ICH) is a highly lethal disease of the elderly. Use of statins is increasingly widespread among the elderly, and therefore common in patients who develop ICH. Accumulating data suggests that statins have neuroprotective effects, but their association with ICH outcome has been inconsistent. We therefore performed a meta-analysis of all available evidence, including unpublished data from our own institution, to determine whether statin exposure is protective for patients who develop ICH.

METHODS

In our prospectively ascertained cohort, we compared 90-day functional outcome in 238 pre-ICH statin cases and 461 statin-free ICH cases. We then meta-analyzed results from our cohort along with previously published studies using a random effects model, for a total of 698 ICH statin cases and 1,823 non-statin-exposed subjects.

RESULTS

Data from our center demonstrated an association between statin use before ICH and increased probability of favorable outcome (odds ratio [OR] = 2.08, 95% confidence interval [CI] 1.37-3.17) and reduced mortality (OR = 0.47, 95% CI 0.32-0.70) at 90 days. No compound-specific statin effect was identified. Meta-analysis of all published evidence confirmed the effect of statin use on good outcome (OR = 1.91, 95% CI 1.38-2.65) and mortality (OR = 0.55, 95% CI 0.42-0.72) after ICH.

CONCLUSION

Antecedent use of statins prior to ICH is associated with favorable outcome and reduced mortality after ICH. This phenomenon appears to be a class effect of statins. Further studies are required to clarify the biological mechanisms underlying these observations.

White matter hyperintensity volume is increased in small vessel stroke subtypes

OBJECTIVE

White matter hyperintensity (WMH) may be a marker of an underlying cerebral microangiopathy. Therefore, we hypothesized that WMH would be most severe in patients with lacunar stroke and intracerebral hemorrhage (ICH), 2 types of stroke in which cerebral small vessel (SV) changes are pathophysiologically relevant.

METHODS

We determined WMH volume (WMHV) in cohorts of prospectively ascertained patients with acute ischemic stroke (AIS) (Massachusetts General Hospital [MGH], n = 628, and the Ischemic Stroke Genetics Study [ISGS], n = 263) and ICH (MGH, n = 122).

RESULTS

Median WMHV was 7.5 cm³ (interquartile range 3.4-14.7 cm³) in the MGH AIS cohort (mean age 65 ± 15 years). MGH patients with larger WMHV were more likely to have lacunar stroke compared with cardioembolic (odds ratio [OR] = 1.87 per SD normally transformed WMHV), large artery (OR = 2.25), undetermined (OR = 1.87), or other (OR = 1.85) stroke subtypes (p < 0.03). These associations were replicated in the ISGS cohort (p = 0.03). In a separate analysis, greater WMHV was seen in ICH compared with lacunar stroke (OR = 1.2, p < 0.02) and in ICH compared with all ischemic stroke subtypes combined (OR = 1.34, p < 0.007).

CONCLUSIONS

Greater WMH burden was associated with SV stroke compared with other ischemic stroke subtypes and, even more strongly, with ICH. These data, from 2 independent samples, support the model that increasing WMHV is a marker of more severe cerebral SV disease and provide further evidence for links between the biology of WMH and SV stroke.

Prior antiplatelet therapy and outcome following intracerebral hemorrhage: a systematic review

OBJECTIVES

Antiplatelet therapy (APT) promotes bleeding; therefore, APT might worsen outcome in patients with intracerebral hemorrhage (ICH). We performed a systematic review and meta-analysis to address the hypothesis that pre-ICH APT use is associated with mortality and poor functional outcome following ICH.

METHODS

The Medline and Embase databases were searched in February 2008 using relevant key words, limited to human studies in the English language. Cohort studies of consecutive patients with ICH reporting mortality or functional outcome according to pre-ICH APT use were identified. Of 2,873 studies screened, 10 were judged to meet inclusion criteria by consensus of 2 authors. Additionally, we solicited unpublished data from all authors of cohort studies with >100 patients published within the last 10 years, and received data from 15 more studies. Univariate and multivariable-adjusted odds ratios (ORs) for mortality and poor functional outcome were abstracted as available and pooled using a random effects model.

RESULTS

We obtained mortality data from 25 cohorts (15 unpublished) and functional outcome data from 21 cohorts (14 unpublished). Pre-ICH APT users had increased mortality in both univariate (OR 1.41, 95% confidence interval [CI] 1.21 to 1.64) and multivariable-adjusted (OR 1.27, 95% CI 1.10 to 1.47) pooled analyses. By contrast, the pooled OR for poor functional outcome was no longer significant when using multivariable-adjusted estimates (univariate OR 1.29, 95% CI 1.09 to 1.53; multivariable-adjusted OR 1.10, 95% CI 0.93 to 1.29).

CONCLUSIONS

In cohort studies, APT use at the time of ICH compared to no APT use was independently associated with increased mortality but not with poor functional outcome.

Prevalence of superficial siderosis in patients with cerebral amyloid angiopathy

BACKGROUND

Cerebral amyloid angiopathy (CAA) typically presents with lobar intracerebral macrohemorrhages (ICH) or microbleeds (MBs). Several case reports also found superficial siderosis (SS) in patients with CAA. We aimed to assess the value of SS for the in vivo diagnosis of CAA, and tested whether the inclusion of SS as a criterion alters the sensitivity and specificity of the Boston criteria for CAA-related hemorrhage.

METHODS

We retrospectively analyzed the T2*-weighted MRIs of 38 patients with histopathologically proven CAA and of 22 control patients with histopathologically proven non-CAA ICHs regarding the presence of ICHs, MBs, and SS. We compared the sensitivity and specificity of the classic Boston criteria to that of modified criteria, which included SS as a criterion.

RESULTS

ICHs were present in 71% of the patients with CAA, and in all control patients. MBs were found in 47.4% of patients with CAA and in 22.7% of controls. SS was detected in 60.5% of patients with CAA, but in none of the controls. The classic criteria had a sensitivity of 89.5% for CAA-related hemorrhage, while inclusion of SS increased their sensitivity to 94.7% (not significant). On the contrary, the specificity of the Boston criteria was 81.2% both for the classic and for the modified criteria.

CONCLUSIONS

Superficial siderosis (SS) occurs with high prevalence in cerebral amyloid angiopathy (CAA) and is rare in non-CAA forms of intracerebral hemorrhages. Thus, we propose that inclusion of SS in the Boston criteria might enhance their sensitivity for CAA-related hemorrhage without loss of specificity.

Feeding, oviposition and survival of Liriomyza trifolii (Diptera: Agromyzidae) on Bt and non-Bt cottons

The effects of Bt transgenic cottons (Bt-I expressing cry1Ac and Bt-II expressing cry1Ab and cry2Ab or cry1Ab and cry1Fa) and non-Bt cottons on feeding, oviposition and longevity of adults, and development and survival of Liriomyza trifolii larvae were studied under laboratory conditions; and infestation on four Bt and two non-Bt cotton traits were investigated under field conditions. Laboratory choice and no-choice tests showed that L. trifolii adults were capable of distinguishing between Bt cottons and non-Bt cottons. In a choice test on younger plants (4-5 leaves), the adults were found more often and made more feeding punctures (FP) on non-Bt cottons than on Bt cottons. On older plants (8-9 leaves), adults made the most FP on non-Bt cotton followed by those on Bt-II cottons and the least on Bt-I cotton. The females oviposited more eggs (6.7 eggs per leaf) on non-Bt cotton than on Bt-I (1.7 eggs per leaf) and Bt-II (0.8 eggs per leaf) cottons on younger plants and oviposited similar numbers of eggs (0.7-1.3 eggs per leaf) on non-Bt and Bt cottons on older plants. In a no-choice test, the females also fed more FP on non-Bt cottons than on Bt cottons on both younger and older plants. The females oviposited more eggs (15.6 eggs per leaf) on non-Bt cotton than on Bt-I (8.2 eggs per leaf) and Bt-II (6.5 eggs per leaf) cottons on younger plants and similar numbers of eggs (2.5-3.3 eggs per leaf) on non-Bt and Bt cottons on older plants. Larval and puparial survivals were not different among Bt and non-Bt cottons. The occurrence and damage of leafminers on cottons in the field showed that L. trifolii infested more plants and leaves and had more mines on non-Bt cotton than on Bt cottons.

Silent ischemic infarcts are associated with hemorrhage burden in cerebral amyloid angiopathy

BACKGROUND

Neuropathologic studies suggest an association between cerebral amyloid angiopathy (CAA) and small ischemic infarctions as well as hemorrhages. We examined the prevalence and associated risk factors for infarcts detected by diffusion-weighted imaging (DWI).

METHODS

We performed retrospective analysis of MR images from 78 subjects with a diagnosis of probable CAA and a similar aged group of 55 subjects with Alzheimer disease or mild cognitive impairment (AD/MCI) for comparison. DWI and apparent diffusion coefficient (ADC) maps were inspected for acute or subacute infarcts. We also examined the association between DWI lesions and demographic variables, conventional vascular risk factors, and radiographic markers of CAA severity such as number of hemorrhages on gradient-echo MRI and volume of T2-hyperintense white matter lesions.

RESULTS

Twelve of 78 subjects with CAA (15%) had a total of 17 DWI-hyperintense lesions consistent with subacute cerebral infarctions vs 0 of 55 subjects with AD/MCI (p = 0.001). The DWI lesions were located primarily in cortex and subcortical white matter. CAA subjects with DWI lesions had a higher median number of total hemorrhages (22 vs 4, p = 0.025) and no difference in white matter hyperintensity volume or conventional vascular risk factors compared to subjects with CAA without lesions.

CONCLUSIONS

MRI evidence of small subacute infarcts is present in a substantial proportion of living patients with advanced cerebral amyloid angiopathy (CAA). The presence of these lesions is associated with a higher burden of hemorrhages, but not with conventional vascular risk factors. This suggests that advanced CAA predisposes to ischemic infarction as well as intracerebral hemorrhage.

Plasma Abeta, homocysteine, and cognition: the Vitamin Intervention for Stroke Prevention (VISP) trial

BACKGROUND

Amyloid-beta protein (Abeta) plays a key role in Alzheimer disease (AD) and is also implicated in cerebral small vessel disease. Serum total homocysteine (tHcy) is a risk factor for small vessel disease and cognitive impairment and correlates with plasma Abeta levels. To determine whether this association results from a common pathophysiologic mechanism, we investigated whether vitamin supplementation-induced reduction of tHcy influences plasma Abeta levels in the Vitamin Intervention in Stroke Prevention (VISP) study.

METHODS

Two groups of 150 patients treated with either the high-dose or low-dose formulation of pyridoxine, cobalamin, and folic acid in a randomized, double-blind fashion were selected among the participants in the VISP study without recurrent stroke during follow-up and in the highest 10% of the distribution for baseline tHcy levels. Concentrations of plasma Abeta with 40 (Abeta40) and 42 (Abeta42) amino acids were measured at baseline and at the 2-year visit.

RESULTS

tHcy levels significantly decreased with vitamin supplementation in both groups. tHcy were strongly correlated with Abeta40 but not Abeta42 concentrations. There was no difference in the change in Abeta40, Abeta42 (p = 0.40, p = 0.35), or the Abeta42/Abeta40 ratio over time (p = 0.86) between treatment groups. Abeta measures were not associated with cognitive change.

CONCLUSIONS

This double-blind randomized controlled trial of vitamin therapy demonstrates a strong correlation between serum tHcy and plasma Abeta40 concentrations in subjects with ischemic stroke. Treatment with high dose vitamins does not, however, influence plasma levels of Abeta, despite their effect on lowering tHcy. Our results suggest that although tHcy is associated with plasma Abeta40, they may be regulated by independent mechanisms.

Impaired visual evoked flow velocity response in cerebral amyloid angiopathy

OBJECTIVE

Animal models of cerebral amyloid angiopathy (CAA) exhibit abnormal vascular reactivity. We determined whether vascular reactivity, measured by transcranial Doppler ultrasound (TCD), is reduced in humans with CAA.

METHODS

Cases were recruited from an established prospective study of CAA. Healthy controls were recruited from a study of normal aging. Evoked mean flow velocity increase in the posterior cerebral artery (PCA) was measured while subjects viewed a flashing alternating checkerboard stimulus. In a separate but partially overlapping cohort we measured the mean flow velocity increase in the middle cerebral artery (MCA) while subjects inhaled carbon dioxide.

RESULTS

The visual evoked mean flow velocity increase was 8.0 +/- 6.1% in CAA (n = 11) compared to 17.4 +/- 5.7% in controls (n = 9, p = 0.002). The PCA pulsatility index, a marker of distal vascular resistance, was higher in CAA (CAA 1.35 +/- 0.35, control 1.04 +/- 0.14, p = 0.03). Among CAA subjects, lower visual evoked mean flow velocity increase was associated with a higher number of hemorrhages seen on MRI (r = -0.87, p = 0.0005) and higher MRI white matter hyperintensity volume (r = -0.67, p = 0.02). The MCA response to carbon dioxide did not differ between CAA and control in 20 subjects (9 CAA, 11 control, p = 0.54).

CONCLUSIONS

Cerebral amyloid angiopathy (CAA) was associated with decreased vascular reactivity in response to visual stimulation, possibly reflecting the occipital predilection of the disease. The association of posterior cerebral artery (PCA) evoked flow velocity response with elevated PCA pulsatility index and MRI markers of small vessel disease suggests that abnormal PCA evoked flow velocity in CAA is caused by pathology of the distal resistance vessels.

Effects of photoperiod on boll weevil (Coleoptera: Curculionidae) development, survival, and reproduction

Effects of photoperiod on development, survival, feeding, and oviposition of boll weevils, Anthonomus grandis grandis Boheman, were assessed under five different photophases (24, 14, 12, 10, and 0 h) at a constant 27 degrees C temperature and 65% RH in the laboratory. Analyses of our results detected positive relationships between photoperiod and puncturing (mean numbers of oviposition and feeding punctures per day), and oviposition (oviposition punctures/oviposition+feeding punctures) activities, and the proportion of squares attacked by boll weevil females. When boll weevil females developed in light:darkness cycles, they produced a significantly higher percentage of eggs developing to adulthood than those developed in 24-h light or dark conditions. In long photoperiod (24:0 and 14:10 h), the number of female progeny was significantly higher and their development time was significantly shorter than those developed in short photoperiod (0:24 and 10:14 h). Lifetime oviposition was significantly highest at 12- and 14-h photophase, lowest at 0- and 10-h photophase, and intermediate at 24 h of light. Life table calculations indicated that boll weevil populations developed in a photoperiod of 14:10 and 12:12 (L:D) h will increase an average of two-fold each generation (Ro) compared with boll weevils developed in 24:0- and 10:14-h photoperiods and 15-fold compared with those at 0:24 h. Knowledge of the photoperiod-dependent population growth potential is critical for understanding population dynamics to better develop sampling protocols and timing insecticide applications.

MR imaging detection of cerebral microbleeds: effect of susceptibility-weighted imaging, section thickness, and field strength

BACKGROUND AND PURPOSE

The emergence of cerebral microbleeds (CMB) as common MR imaging findings raises the question of how MR imaging parameters influence CMB detection. To evaluate the effects of modified gradient recalled-echo (GRE) MR imaging methods, we performed an analysis of sequence, section thickness, and field strength on CMB imaging properties and detection in subjects with cerebral amyloid angiopathy (CAA), a condition associated with microhemorrhage.

MATERIALS AND METHODS

Multiple MR images were obtained from subjects with probable CAA, with varying sequences (GRE versus susceptibility-weighted imaging [SWI]), section thicknesses (1.2-1.5 versus 5 mm), and magnetic field strengths (1.5T versus 3T). Individual CMB were manually identified and analyzed for contrast index (lesion intensity normalized to normal-appearing white matter signal intensity) and diameter. CMB counts were compared between 1.5T thick-section GRE and thin-section SWI for 3 subjects who underwent both protocols in the same scanning session.

RESULTS

With other parameters constant, use of SWI, thinner sections, and a higher field strength yielded medium-to-large gains in CMB contrast index (CI; Cohen d 0.71-1.87). SWI was also associated with small increases in CMB diameter (Cohen d <0.3). Conventional thick-section GRE identified only 33% of CMB (103 of 310) seen on thin-section SWI. Lesions prospectively identified on GRE had significantly greater CI and diameter measured on the GRE image than those not prospectively identified.

CONCLUSIONS

The examined alternatives to conventional GRE MR imaging yield substantially improved CMB contrast and sensitivity for detection. Future studies based on these techniques will most likely yield even higher prevalence estimates for CMB.

Course of cerebral amyloid angiopathy-related inflammation

BACKGROUND

A subset of patients with cerebral amyloid angiopathy (CAA) present with cognitive symptoms, seizures, headaches, T2-hyperintense MRI lesions, and neuropathologic evidence of CAA-associated vascular inflammation.

OBJECTIVE

To analyze the risk factors, diagnostic characteristics, and long-term course of this disorder.

METHODS

We assessed 14 consecutive patients with pathologically diagnosed CAA-related inflammation, 12 with available neuroimaging and follow-up data. Patients were evaluated for MRI appearance, APOE genotype, and clinical course over a 46.8 +/- 29.1-month follow-up.

RESULTS

Baseline MRI scans were characterized by asymmetric T2-hyperintense lesions extending to the subcortical white matter and occasionally the overlying gray matter, with signal properties suggesting vasogenic edema. Subjects could be divided into three groups based on response to immunosuppressive treatment: monophasic improvement (7/12), initial improvement followed by symptomatic relapse (3/12), and no evident response to treatment (2/12). The volume of MRI hyperintensities correlated with the severity of clinical symptoms. One patient experienced symptomatic intracerebral hemorrhage within a region of recurrent MRI hyperintensity. The APOE epsilon4/epsilon4 genotype was strongly associated with CAA-related inflammation, present in 76.9% (10/13) of subjects vs 5.1% (2/39) with symptomatic but noninflammatory CAA (p < 0.0001).

CONCLUSION

Cerebral amyloid angiopathy-related inflammation represents a clinically, pathologically, radiographically, and genetically distinct disease subtype with implications for clinical practice and ongoing immunotherapeutic approaches to Alzheimer disease.

Contrast extravasation on CT angiography predicts hematoma expansion in intracerebral hemorrhage

BACKGROUND

Patients with acute intracerebral hemorrhage (ICH) presenting within 3 hours of symptom onset are known to be at increased risk of expansion. However, only a minority arrive within this time frame. Therefore, alternative markers for expansion risk are needed.

OBJECTIVE

To examine whether contrast extravasation on CT angiography (CTA) at presentation predicts subsequent hematoma expansion.

METHODS

Consecutive patients with primary ICH presenting to an urban tertiary care hospital were prospectively captured in a database. We retrospectively reviewed images for all patients receiving a CTA and at least one further CT scan within 48 hours.

RESULTS

Complete data were available for 104 patients. Contrast extravasation at the time of CTA was present in 56% of patients, and associated with an increased risk of hematoma expansion (22% vs 2%, p = 0.003). Patients who received a baseline CTA within 3 hours were more likely to have subsequent expansion (27%, vs 13% for those presenting later, p = 0.1). However, after multivariable analysis, contrast extravasation was the only significant predictor of hematoma expansion (OR 18, 95% CI 2.1 to 162). This effect was independent of time to presentation.

CONCLUSIONS

Contrast extravasation is independently associated with hematoma expansion. Patients presenting within the first few hours after symptom onset have traditionally been considered those at highest risk of expansion. However, for those presenting later, the presence of contrast may be a useful marker to guide therapies aimed at decreasing this risk.

Reproductive potential of overwintering, F1, and F2 female boll weevils (Coleoptera: Curculionidae) in the Lower Rio Grande Valley of Texas

The feeding and oviposition activity of overwintering boll weevils, Anthonomus grandis grandis (Boheman), and seasonal fluctuations in development, survival, and reproduction of progeny of overwintering and first- and second-generation boll weevil females were determined in the laboratory at 27 degrees C, 65% RH, and a photoperiod of 12:12 (L:D) h. During the cotton-free period in the Lower Rio Grande Valley, female boll weevils without access to cotton resorb their unlaid eggs and enter reproductive diapause. However, when they were provided daily with greenhouse-grown cotton squares, commencement of oviposition began after 7, 15, or 20 d, depending on when they were captured. Females captured later in the winter fed longer before laying eggs than those captured in the early fall, suggesting that it may take females longer to terminate diapause the longer they have been dormant. The rate of feeding by females was significantly less during the winter months, and this may have affected the rate of diet-mediated termination of dormancy. Females of the first and second generations after the overwintering generation produced a significantly higher percentage of progeny surviving to adulthood and a higher proportion of these progeny were females. Offspring development time from overwintering female parents was significantly longer than that from first and second generations under the same laboratory conditions. The total number of lifetime eggs produced by females of the second generation during the cotton-growing season were approximately 9.9-fold higher than for overwintering females and 1.5-fold higher than for first-generation females. Life table calculations indicated that the population of second-generation boll weevils increased an average of 1.5-fold higher each generation than for females of the first generation and 22.6-fold higher than for overwintering females. Our data showed variation in boll weevil survival, development, and reproductive potential among the overwintering and first- and second-generation females, suggesting inherent seasonal fluctuations in these parameters.

Prevalence and effects of lobar microhemorrhages in early-stage dementia

BACKGROUND

80-100% of patients with Alzheimer's disease have vascular pathology related to cerebral amyloid angiopathy (CAA), and 5-7% have CAA-related lobar microhemorrhages (LMH) at autopsy. The prevalence and effects of LMH detectable by gradient echo MRI (GE-MRI) in early-stage dementia are unknown.

OBJECTIVE

To obtain, using GE-MRI, a prevalence estimate for LMH in patients with early-stage dementia and to assess the effects of LMH on dementia severity.

METHODS

Eighty-four subjects aged >or=55 years (range 58-89; mean 76) underwent cognitive and GE-MRI evaluation. The 84 subjects consisted of 61 consecutive subjects evaluated as part of an initial clinical evaluation for dementia and 23 consecutively evaluated healthy older subjects (controls). Data were analyzed for presence and number of LMH on GE-MRI and the effect of number of LMH on dementia severity.

RESULTS

Nine (15%) of the 61 dementia patients versus 1 (4%) of the 23 control subjects demonstrated LMH on GE-MRI. Multiple (>or=2) LMH were found in 7 of the 9 (88%) dementia subjects with LMH (range of LMH counts 1-330) and no (0%) control subjects. Multivariable causal modeling indicated that number of LMH (p < 0.02), age (p < 0.01) and duration of symptoms (p < 0.001) significantly increased dementia severity while higher educational level (p < 0.001) was protective.

CONCLUSIONS

LMH were detected by GE-MRI in 15% of patients with early-stage dementia and may contribute to dementia severity.

Progression of white matter lesions and hemorrhages in cerebral amyloid angiopathy

OBJECTIVE

To determine the rate of progression of white matter lesions and hemorrhages in a cohort with cerebral amyloid angiopathy (CAA).

METHODS

The authors analyzed data from 26 patients with possible (3) or probable (23) CAA, diagnosed by the Boston Criteria. Brain maps of white matter hyperintensities, normalized to head size (nWMH), were created by blinded computer-assisted segmentation of MRI images obtained at baseline and after a median follow-up interval of 1.1 year.

RESULTS

There was a substantial nWMH volume increase over the interscan interval (median 0.5 mL/year, interquartile range 0.1 to 2.8, p < 0.001). The median yearly increase, expressed as a percentage of the baseline WMH volume, was 18%. The characteristic most strongly associated with nWMH volume increase was the baseline nWMH volume (r = 0.57, p = 0.002). The volume of nWMH progression was also associated with history of cognitive impairment (median 5.0 mL/year in cognitively impaired subjects vs 0.3 mL/year in cognitively unimpaired, p = 0.02) but not age or hypertension. This association remained present in an analysis stratified by baseline WMH volume. New hemorrhages, including asymptomatic microbleeds, were seen in 46% of subjects. The number of new MRI hemorrhages correlated strongly with baseline nWMH (r = 0.53, p = 0.005) but not with nWMH progression (r = 0.22, p = 0.28).

CONCLUSIONS

There is a progressive increase in white matter lesions in subjects with cerebral amyloid angiopathy. The association of white matter lesions with incident lobar hemorrhages suggests that white matter damage may reflect a progressive microangiopathy due to cerebral amyloid angiopathy.

Plasma beta-amyloid and white matter lesions in AD, MCI, and cerebral amyloid angiopathy

BACKGROUND

Microvascular brain injury, typically measured by extent of white matter hyperintensity (WMH) on MRI, is an important contributor to cognitive impairment in the elderly. Recent studies suggest a role for circulating beta-amyloid peptide in microvascular dysfunction and white matter disease.

METHODS

The authors performed a cross-sectional study of clinical, biochemical, and genetic factors associated with WMH in 54 subjects with Alzheimer disease (AD) or mild cognitive impairment (AD/MCI) and an independent group of 42 subjects with cerebral amyloid angiopathy (CAA). Extent of WMH was determined by computer-assisted volumetric measurement normalized to intracranial size (nWMH). Biochemical measurements included plasma concentrations of the 40- and 42-amino acid species of beta-amyloid (Abeta40 and Abeta42) detected by specific enzyme-linked immunosorbent assays.

RESULTS

Plasma Abeta40 concentrations were associated with nWMH in both groups (correlation coefficient = 0.48 in AD/MCI, 0.42 in CAA, p < or = 0.005). Plasma Abeta40 remained independently associated with nWMH after adjustment for potential confounders among age, hypertension, diabetes, homocysteine, creatinine, folate, vitamin B12, and APOE genotype. The presence of lacunar infarctions was also associated with increased Abeta40 in both groups. nWMH was greater in CAA (19.8 cm3) than AD (11.1 cm3) or MCI (10.0 cm3; p < 0.05 for both comparisons).

CONCLUSIONS

Plasma beta-amyloid 40 concentration is independently associated with extent of white matter hyperintensity in subjects with Alzheimer disease, mild cognitive impairment, or cerebral amyloid angiopathy. If confirmed in longitudinal studies, these data would suggest circulating beta-amyloid peptide as a novel biomarker or risk factor for microvascular damage in these common diseases of the elderly.

Antiplatelet use after intracerebral hemorrhage

BACKGROUND

Survivors of intracerebral hemorrhage are at risk for recurrent intracerebral hemorrhage and ischemic cardiovascular and cerebrovascular disease.

OBJECTIVE

To determine whether antiplatelet therapy increases the risk of recurrent intracerebral hemorrhage.

METHODS

The authors reviewed data from consecutive survivors of primary intracerebral hemorrhage enrolled in a single-center prospective cohort study. Survivors were followed by telephone interview; recurrent intracerebral hemorrhage and post-index antiplatelet agent use and duration were recorded. Cox proportional hazards models was used with antiplatelet agent exposure as a time-dependent variable to assess the effect of antiplatelet agent use on recurrent intracerebral hemorrhage, stratified by lobar and deep hemispheric location.

RESULTS

Recurrent intracerebral hemorrhage was more common in survivors of lobar hemorrhage compared with survivors of deep hemorrhage (cumulative 2-year rate 22% vs 4%; p = 0.007). Antiplatelet agents were prescribed in 22% of intracerebral hemorrhage survivors (27/127 lobar, 19/80 deep hemispheric), most commonly for prevention of ischemic heart disease. Antiplatelet agent use was not associated with intracerebral hemorrhage recurrence in survivors of either lobar hemorrhage (hazard ratio [HR] 0.8, 95% CI 0.3 to 2.3, p = 0.73) or of deep hemorrhage (HR 1.2, 95% CI 0.1 to 14.3, p = 0.88).

CONCLUSION

Antiplatelet agent use is relatively common following intracerebral hemorrhage but did not appear to be associated with a large increased risk of intracerebral hemorrhage recurrence in this observational study.

Current Pharmacotherapy for Alzheimer's Disease

Alzheimer's disease (AD) is an age-related neurodegenerative disease that affects approximately 4.5 million people in the United States. The mainstays of current pharmacotherapy for AD are compounds aimed at increasing the levels of acetylcholine in the brain, thereby facilitating cholinergic neurotransmission through inhibition of the cholinesterases. These drugs, known as acetylcholinesterase inhibitors (AChEIs), were first approved by the U.S. Food and Drug Administration (FDA) in 1995 based on clinical trials showing modest symptomatic benefit on cognitive, behavioral, and global measures. In 2004 the FDA approved memantine, an NMDA antagonist, for treating dementia symptoms in moderate to severe AD cases. In clinical practice, memantine may be co-administered with an AChEI, although neither drug individually or in combination affects the underlying pathophysiology of dementia. Dementia in AD results from progressive synaptic loss and neuronal death. As knowledge of the mechanisms responsible for neurodegeneration in AD increases, it is anticipated that neuroprotective drugs to slow or prevent neuronal dysfunction and death will be developed to complement current symptomatic treatments.

Association of homocysteine with plasma amyloid β protein in aging and neurodegenerative disease

BACKGROUND

Elevated plasma total homocysteine (tHcy) is a risk factor for cardiovascular disease and is reported to be an independent risk factor for Alzheimer disease (AD) and cognitive decline. tHcy may potentiate neurotoxic and vasculopathic processes, including amyloid beta protein (Abeta) metabolism, implicated in neurodegenerative diseases.

OBJECTIVE

To examine the relationship of plasma total tHcy levels with clinical, demographic, biochemical, and genetic factors in aging, mild cognitive impairment (MCI), AD, cerebral amyloid angiopathy (CAA), and Parkinson disease (PD).

METHODS

Plasma tHcy, folate, vitamin B(12), creatinine, and Abeta levels were assessed in individuals evaluated in the Memory, Stroke, and Movement Disorders Units of Massachusetts General Hospital with diagnoses of AD (n = 145), MCI (n = 47), PD (n = 93), CAA (67), hypertensive intracerebral hemorrhage (hICH) (n = 25), and no dementia (n = 88).

RESULTS

The tHcy levels did not differ across AD, MCI, CAA, hICH, and nondemented control subjects but were increased in the PD group (p < 0.01). The elevated levels within the PD group were due to high tHcy in individuals taking levodopa (p < 0.0001). Increasing tHcy was associated with worse cognition in the PD cases, but not the other diagnostic groups. tHcy levels positively correlated with plasma Abeta levels even after adjustments for age and creatinine (p < 0.0001).

CONCLUSIONS

Mean tHcy levels increased with age but did not discriminate diagnostic groups aside from significant elevation in patients with PD taking levodopa. The positive association between tHcy and plasma Abeta levels raises the possibility that these circulating factors could interact to affect AD risk and cognition in PD.

White matter lesions, cognition, and recurrent hemorrhage in lobar intracerebral hemorrhage

BACKGROUND

Accumulating evidence suggests that white matter lesions are associated with vascular cognitive impairment. The authors investigated the relationships between white matter lesions, cognitive impairment, and risk of recurrent hemorrhage in a prospectively identified cohort of patients with lobar intracerebral hemorrhage (ICH).

METHODS

The authors collected clinical and genetic information on 182 consecutive patients age > or = 55 who had CT scan at admission for lobar ICH. White matter disease was graded on CT in all subjects and on MRI in a subset of 82 patients. All scans were interpreted blinded to clinical information. Survivors were followed for recurrent ICH by telephone interview.

RESULTS

White matter damage was common (present on CT in 77%) and severe (advanced CT grade in 32%). White matter damage was correlated with the total number of hemorrhages on gradient-echo MRI and with risk of recurrent ICH. Subjects with cognitive impairment prior to their index ICH were more likely to have severe white matter damage on CT (OR 3.6, 95% CI 1.6 to 8.1, p = 0.003) and more likely to have advanced periventricular hyperintensities on MRI. The relationships between white matter damage and cognitive impairment were similar in the subset of 88 subjects meeting criteria for probable or definite cerebral amyloid angiopathy and remained independent after adjustment for age, cortical atrophy, and APOE genotype.

CONCLUSIONS

White matter damage in lobar ICH is common and is associated with cognitive impairment. These data support the possibility that an underlying vasculopathy in lobar ICH patients, possibly cerebral amyloid angiopathy, can cause clinically important vascular dysfunction.

Size-dependent feeding and reproduction by boll weevil (Coleoptera: Curculionidae)

The considerable variation in adult size of the boll weevil, Anthonomus grandis grandis Boheman, has been well documented, but the influences of adult size on reproductive rate are not known. We examined the relationship between the size of boll weevils and their feeding and oviposition. Weevils weighed to the nearest milligram were grouped into five categories based on pupal weight: < or =5, 6-10, 11-15, 16-20, and >20 mg. Numbers of lifetime punctures produced in flower buds (squares) of cotton, Gossypium hirsutum L., by both sexes of adults tended to increase with pupal weight. Boll weevil females with pupal weights >10 mg produced progeny with significantly higher survival to adulthood and also produced a higher percentage of female progeny than those with pupal weights < or =10 mg. The population growth indices for females having pupal weights >10 mg averaged 1.8-fold higher than those of females weighing < or =10 mg. Survivorship of adults of both sexes also tended to increase with pupal weight. The percentage of females laying eggs on any given day averaged 2.1 times higher when their pupal weights were >10 mg than when their pupal weights were < or =10 mg. Although small size negatively affected female reproductive potential, even extremely small females produced some viable offspring. However, the penalties of small adult size, in terms of longevity and reproductive potential, suggest that cultural practices that result in the production of small adults may be used to impact weevil populations.

Effects of planting dates on boll weevils (Coleoptera: Curculionidae) and cotton fruit in the subtropics

The effects of planting dates 2-3-wk apart on boll weevil, Anthonomus grandis grandis Boheman (Coleoptera: Curculionidae), field-level populations, and feeding and oviposition damage to cotton, Gossypium hirsutum L., squares and bolls, were studied during 2002 and 2003 in the Lower Rio Grande Valley of Texas. Squares were 44-56% more abundant in some later planted treatments than in the earlier planted treatments, but mean cumulative numbers of oviposition- and feeding-damaged squares were 2.7 - 4.8-fold greater in some later planted treatments than in earlier treatments. Increased square production in later planted cotton was offset by boll weevil infestations that occurred when squares are most vulnerable and contribute most toward the pest's reproduction. Early planting avoided boll weevil population buildups in the field when large squares were abundant. Lint yields in 2002 did not differ significantly between the planting date treatments, but in 2003, mean yield in the middle treatment was 23% greater than in the early and late-planted treatments. Insecticide sprays in the earliest planted treatment of each year, based on the 10% damaged squares threshold, were >33% and >43% fewer than in the corresponding middle and latest planting treatments, respectively. Delayed planting, relative to the onset of favorable cotton-growing weather, at the field level, even when not applied uniformly on an areawide scale, is more cost-effective than planting too early or too late.

Warfarin, hematoma expansion, and outcome of intracerebral hemorrhage

BACKGROUND

Warfarin increases mortality of intracerebral hemorrhage (ICH). The authors investigated whether this effect reflects increased baseline ICH volume at presentation or increased ICH expansion.

METHODS

Subjects were drawn from an ongoing prospective cohort study of ICH outcome. The effect of warfarin on baseline ICH volume was studied in 183 consecutive cases of supratentorial ICH age > or = 18 years admitted to the emergency department over a 5-year period. Baseline ICH volume was determined using computerized volumetric analysis. The effect of warfarin on ICH expansion (increase in volume > or = 33% of baseline) was analyzed in 70 consecutive cases in whom ICH volumes were measured on all subsequent CT scans up to 7 days after admission. Multivariable analysis was used to determine warfarin's influence on baseline ICH, ICH expansion, and whether warfarin's effect on ICH mortality was dependent on baseline volume or subsequent expansion.

RESULTS

There was no effect of warfarin on initial volume. Predictors of larger baseline volume were hyperglycemia (p < 0.0001) and lobar hemorrhage (p < 0.0001). Warfarin patients were at increased risk of death, even when controlling for ICH volume at presentation. Warfarin was the sole predictor of expansion (OR 6.2, 95% CI 1.7 to 22.9) and expansion in warfarin patients was detected later in the hospital course compared with non-warfarin patients (p < 0.001). ICH expansion showed a trend toward increased mortality (OR 3.5, 95% CI 0.7 to 8.9, p = 0.14) and reduced the marginal effect of warfarin on ICH mortality.

CONCLUSIONS

Warfarin did not increase ICH volume at presentation but did raise the risk of in-hospital hematoma expansion. This expansion appears to mediate part of warfarin's effect on ICH mortality.

Effects of burial and soil condition on postharvest mortality of boll Weevils (Coleoptera: Curculionidae) in fallen cotton fruit

Effects of soil condition and burial on boll weevil, Anthonomus grandis grandis Boheman, mortality in fallen cotton, Gossypium hirsutum L., fruit were assessed in this study. During hot weather immediately after summer harvest operations in the Lower Rio Grande Valley of Texas, burial of infested fruit in conventionally tilled field plots permitted significantly greater survival of weevils than in no-tillage plots. Burial of infested squares protected developing weevils from heat and desiccation that cause high mortality on the soil surface during and after harvest in midsummer and late summer. A laboratory assay showed that burial of infested squares resulted in significantly greater weevil mortality in wet than in dry sandy or clay soils. Significantly fewer weevils rose to the soil surface after burial of infested bolls during winter compared with bolls set on the soil surface, a likely result of wetting by winter rainfall. A combination of leaving infested fruit exposed to heat before the onset of cooler winter temperatures and burial by tillage when temperatures begin to cool might be an important tactic for reducing populations of boll weevils that overwinter in cotton fields.

Deterrent effects of four neem-based formulations on gravid female boll weevil (Coleoptera: Curculionidae) feeding and oviposition on cotton squares

Three commercial neem-based insecticides, Agroneem, Ecozin, and Neemix, and a neem seed extract formulation, bitters, containing 1,036, 16,506, 471, and 223 microg/ml azadirachtin, respectively, were assessed for feeding and oviposition deterrence against gravid female boll weevils, Anthonomus grandis grandis Boheman, in the laboratory. In choice assays, excised cotton squares dipped in the separate formulations were first physically contacted by the weevils' tarsi or antennae fewer times than nontreated control squares. In choice and no-choice assays, each formulation repelled the weevils for > or = 90 min. After 24 h in the choice assays, feeding punctures on the squares treated with Agroneem, Ecozin, or bitters were significantly fewer compared with controls. Egg punctures on the Ecozin- and the bitters-treated squares were significantly fewer than on control squares after 24 h. In the no-choice assay, no significant difference was detected. Aging the formulations under outdoor conditions for 24 h before weevils were exposed resulted in 46-60% and 62-82% reductions in feeding and oviposition punctures, respectively, compared with controls. Agroneem- and bitters-treated squares had > 37% fewer feeding punctures after being aged for 48 h. No significant difference was detected after 72 h of aging. Because the deterrence of the gravid female boll weevils was not correlated with amounts of azadirachtin, azadirachtin does not seem to be the only, or the most influential, component of neem that induced the observed deterrence.

Hemorrhagic stroke associated with the Iowa amyloid precursor protein mutation

The authors searched for mutations in the beta-amyloid precursor protein in a Spanish family with a hereditary syndrome of hemorrhagic stroke, dementia, leukoencephalopathy, and occipital calcifications. DNA from two affected members demonstrated the Iowa amyloid precursor protein mutation previously identified as a cause of severe amyloid angiopathy without hemorrhagic stroke. These data point to other genetic or environmental factors that may determine the occurrence of symptomatic hemorrhage in amyloid angiopathy.

Leukoaraiosis is associated with warfarin-related hemorrhage following ischemic stroke

BACKGROUND AND OBJECTIVES

Prior ischemic stroke is a risk factor for intracerebral hemorrhage (ICH) in patients taking warfarin, but the mechanism is not known. This study investigates radiographic and clinical characteristics of patients with warfarin-related ICH following ischemic stroke.

METHODS

In this case-control study, the authors selected all patients with warfarin-related ICH and previous symptomatic ischemic stroke from a prospective cohort of consecutive patients with ICH. Control subjects were similarly aged patients with history of symptomatic stroke randomly chosen from an anticoagulant therapy unit. The 26 eligible ICH cases and 56 controls were compared for vascular risk factors, stroke characteristics, and extent of leukoaraiosis (graded in anterior and posterior brain regions on a validated scale of 0 to 4).

RESULTS

The presence and severity of leukoaraiosis on CT scan correlated strongly with the occurrence of ICH. Leukoaraiosis was seen in 24 of 26 cases (92%) compared with 27 of 56 controls (48%), yielding an odds ratio of 12.9 (95% CI 2.8 to 59.8). Other clinical factors associated with ICH included an international normalized ratio >3.0, history of multiple previous strokes, and the presence of carotid artery stenosis. The relationship between leukoaraiosis and ICH persisted in multivariable analyses controlling for these risk factors as well as hypertension and diabetes mellitus.

CONCLUSIONS

Leukoaraiosis is an independent risk factor for warfarin-related ICH in survivors of ischemic stroke, including those in the commonly employed range of anticoagulation.

Pathogenic effects of D23N Iowa mutant amyloid beta -protein

Cerebral amyloid beta-protein angiopathy (CAA) is a key pathological feature of patients with Alzheimer's disease and certain related disorders. In these conditions the CAA is characterized by the deposition of Abeta within the cerebral vessel wall and, in severe cases, hemorrhagic stroke. Several mutations have been identified within the Abeta region of the Abeta protein precursor (AbetaPP) gene that appear to enhance the severity of CAA. We recently described a new mutation within the Abeta region (D23N) of AbetaPP that is associated with severe CAA in an Iowa kindred (Grabowski, T. J., Cho, H. S., Vonsattel, J. P. G., Rebeck, G. W., and Greenberg, S. M. (2001) Ann. Neurol. 49, 697-705). In the present study, we investigated the effect of this new D23N mutation on the processing of AbetaPP and the pathogenic properties of Abeta. Neither the D23N Iowa mutation nor the E22Q Dutch mutation affected the amyloidogenic processing of AbetaPP expressed in H4 cells. The A21G Flemish mutation, in contrast, resulted in a 2.3-fold increase in secreted Abeta peptide. We also tested synthetic wild-type and mutant Abeta40 peptides for fibrillogenesis and toxicity toward cultured human cerebrovascular smooth muscle (HCSM) cells. The E22Q Dutch, D23N Iowa, and E22Q,D23N Dutch/Iowa double mutant Abeta40 peptides rapidly assembled in solution to form fibrils, whereas wild-type and A21G Flemish Abeta40 peptides exhibited little fibril formation. Similarly, the E22Q Dutch and D23N Iowa Abeta40 peptides were found to induce robust pathologic responses in cultured HCSM cells, including elevated levels of cell-associated AbetaPP, proteolytic breakdown of smooth muscle cell alpha-actin, and cell death. Double mutant E22Q,D23N Dutch/Iowa Abeta40 was more potent than either single mutant form of Abeta in causing pathologic responses in HCSM cells. These data suggest that the different CAA mutations in AbetaPP may exert their pathogenic effects through different mechanisms. Whereas the A21G Flemish mutation appears to enhance Abeta production, the E22Q Dutch and D23N Iowa mutations enhance fibrillogenesis and the pathogenicity of Abeta toward HCSM cells.

The effects of AbetaPP mutations and APOE polymorphisms on cerebral amyloid angiopathy

Analysis of causative mutations and genetic risk factors aid in the understanding of important processes of cerebral amyloid angiopathy (CAA) in humans. We identified a mutation at a novel site of the beta-amyloid precursor protein (AbetaPP) gene associated with familial CAA; this mutation causes an aspartate to asparagine substitution at position 23 of the Abeta peptide. Neuropathological analysis of a 68-year-old man with this mutation showed dramatic Abeta deposition in blood vessels, diffiuse parenchymal Abeta deposits, dystrophic neurites and neurofibrillary tangles. The Abeta deposition showed complete co-localization of Abeta40 and Abeta42, compared to the predominant Abeta42 deposition seen in AD. We hypothesize that the loss of an acidic residue at position 23 of Abeta might be important in the process of Abeta aggregation on smooth muscle cells on the cerebrovasculature. We also analyzed how the apolipoprotein E (APOE) gene might influence aggregation of Abeta by examining the physical association of apoE domains with Abeta via immunohistochemistry. We found that the lipid-binding domain of apoE was more strongly associated with Abeta than the receptor-binding domain, and that 40% of all Abeta deposits had no apoE bound to them. We suggest that the initial deposition of Abeta occurs in the absence of apoE, and that the process of Abeta deposit growth or stabilization is apoE-dependent.

Outcome markers for clinical trials in cerebral amyloid angiopathy

Determining the effectiveness of candidate treatments for preventing hemorrhagic strokes caused by cerebral amyloid angiopathy will require clinical drug trials. This article explores tvo potential outcome markers for such trials: (1) clinical recurrence of hemorrhagic stroke, and (2) the appearance of small, clinically silent hemorrhagic lesions on gradient-echo MRI. Using pilot data from our cohort of survivors of lobar hemorrhage, we estimated the sample sizes required to demonstrate efficacy with each of these outcome markers as the study endpoint. A study with recurrent hemorrhagic stroke as the endpoint was estimated to require 145 patients per treatment arm to demonstrate a 50% reduction in the recurrence rate over a 24-month follow-up period, while a study using new hemorrhagic lesions on MRI was estimated to require 70 patients per arm for a 17-month follow-up interval. The required sample sizes could be further reduced (to 105 and 52 patients, respectively) by limiting the analysis to those at highest risk of recurrence, defined according to apolipoprotein E genotype or the presence of more than one hemorrhagic lesion at study entry. This analysis suggests that radiographic detection of small hemorrhages may be an efficient surrogate endpoint for pilot trials of promising therapeutic approaches to cerebral amyloid angiopathy.

Novel amyloid precursor protein mutation in an Iowa family with dementia and severe cerebral amyloid angiopathy

Several mutations in the amyloid precursor protein (APP) gene have been found to associate with pathologic deposition of the beta-amyloid peptide (Abeta) in neuritic plaques or in the walls of cerebral vessels. We report a mutation at a novel site in APP in a three-generation Iowa family with autosomal dominant dementia beginning in the sixth or seventh decade of life. The proband and an affected brother had progressive aphasic dementia, leukoencephalopathy, and occipital calcifications. Neuropathological examination of the proband revealed severe cerebral amyloid angiopathy, widespread neurofibrillary tangles, and unusually extensive distribution of Abeta40 in plaques. The affected brothers shared a missense mutation in APP, resulting in substitution of asparagine for aspartic acid at position 694. This site corresponds to residue 23 of Abeta, thus differing from familial Alzheimer's disease mutations, which occur outside the Abeta sequence. Restriction enzyme analysis of DNA from 94 unrelated patients with sporadic cerebral amyloid angiopathy-related hemorrhage found no other instances of this mutation. These results suggest a novel site within Abeta that may promote its deposition and toxicity.

Quantitation of apoE domains in Alzheimer disease brain suggests a role for apoE in Abeta aggregation

Apolipoprotein E (apoE) and apoE-derived proteolytic fragments are present in amyloid deposits in Alzheimer disease (AD) and cerebral amyloid angiopathy (CAA). In this study, we examined which apoE fragments are most strongly associated with amyloid deposits and whether apoE receptor binding domains were present. We found that both apoE2- and apoE4-specific residues were present on plaques and blood vessels in AD and CAA. We quantified Abeta plaque burden and apoE plaque burdens in 5 AD brains. ApoE N-terminal-specific and C-terminal-specific antibodies covered 50% and 74% of Abeta plaque burden, respectively (p < 0.003). Double-labeling demonstrated that the plaque cores contained the entire apoE protein, but that outer regions contained only a C-terminal fragment, suggesting a cleavage in the random coil region of apoE. Presence of N- and C-terminal apoE cleavage fragments in brain extracts was confirmed by immunoblotting. The numbers of plaques identified by the apoE N-terminal-specific antibodies and the apoE C-terminal-specific antibody were equal, but were only approximately 60% of the total Abeta plaque number (p < 0.0001). Analysis of the size distribution of Abeta and apoE deposits demonstrated that most of the Abeta-positive, apoE-negative deposits were the smallest deposits (less than 150 microm2). These data suggest that C-terminal residues of apoE bind to Abeta and that apoE may help aid in the progression of small Abeta deposits to larger deposits. Furthermore, the presence of the apoE receptor binding domain in the center of amyloid deposits could affect surrounding cells via chronic interactions with cell surface apoE receptors.

Clinical diagnosis of cerebral amyloid angiopathy: validation of the Boston criteria

The authors performed clinical-pathologic correlation to assess the validity of the Boston diagnostic criteria for cerebral amyloid angiopathy (CAA). Thirteen subjects were diagnosed clinically with probable CAA from among 39 patients with available pathologic tissue in a prospective cohort of subjects aged > or = 55 years with primary lobar hemorrhage. All 13 individuals were confirmed neuropathologically as having CAA. This small pathologic series indicates that the diagnosis of probable CAA can be made during life with high accuracy.

Warfarin-associated hemorrhage and cerebral amyloid angiopathy: a genetic and pathologic study

BACKGROUND

Intracerebral hemorrhage (ICH) is the most feared complication of warfarin therapy. The pathogenesis of this often-fatal complication remains obscure. Cerebral amyloid angiopathy (CAA) is a major cause of spontaneous lobar hemorrhage in the elderly and is associated with specific alleles of the APOE gene.

OBJECTIVE

To assess the role of CAA in warfarin-associated ICH.

METHODS

Clinical characteristics and APOE genotype were compared between 41 patients with warfarin-related ICH (from a cohort of 59 consecutive patients aged > or = 65 years with supratentorial ICH on warfarin) and 66 randomly selected individuals aged > or = 65 years without ICH taking warfarin. In addition, all neuropathologic specimens from ICH patients were reviewed for the presence and severity of CAA.

RESULTS

Hemorrhages tended to be in the lobar regions of the brain, and most (76%) occurred with an international normalized ratio of < or = 3.0. The APOE epsilon2 allele was overrepresented among patients with warfarin-associated lobar hemorrhage (allele frequency 0.13 versus 0.04 in control subjects; p = 0.031). After controlling for other variables associated with ICH, carriers of the epsilon2 allele had an OR of 3.8 (95% CI, 1.0 to 14.6) for lobar ICH. CAA was pathologically diagnosed as the cause of lobar hemorrhage in 7 of 11 patients with available tissue samples.

CONCLUSIONS

CAA is an important cause of warfarin-associated lobar ICH in the elderly. Although diagnosis of CAA before hemorrhage is not yet possible, these data offer hope that future patients at high risk for hemorrhage may be identified before initiation of warfarin therapy.

Plasma beta-amyloid peptide, transforming growth factor-beta 1, and risk for cerebral amyloid angiopathy

Despite the documented association between apolipoprotein E genotype and cerebral amyloid angiopathy (CAA), a substantial proportion of CAA-related hemorrhages occur in patients without known risks for this disorder. Two other factors implicated in the pathogenesis of CAA are the amyloid-beta peptide (preferentially deposited in vessels as a 40-amino acid species) and the multifunctional cytokine transforming growth factor-beta 1 (a specific promoter of vascular amyloid deposition in transgenic models). We measured plasma concentrations of these factors in a series of 25 patients diagnosed with probable or definite CAA-related hemorrhage and compared them with 21 patients with hemorrhage due to probable hypertensive vasculopathy and 42 elderly control subjects without hemorrhage. We found no differences among the groups in concentrations of the 40- or 42-amino acid species of beta-amyloid or either the active or latent form of transforming growth factor-beta 1. While the data do not exclude important roles for these molecules as risks for CAA, they indicate that plasma measurements are not useful in its diagnosis.

Apolipoprotein E genotype and the risk of recurrent lobar intracerebral hemorrhage

BACKGROUND

Recurrent lobar intracerebral hemorrhage is the hallmark of cerebral amyloid angiopathy. The factors that predispose patients to early recurrence of lobar hemorrhage are unknown. One candidate is the apolipoprotein E gene, since both the epsilon2 and the epsilon4 alleles of apolipoprotein E appear to be associated with the severity of amyloid angiopathy.

METHODS

We performed a prospective, longitudinal study of consecutive elderly patients who survived a lobar intracerebral hemorrhage. The patients were followed for recurrent hemorrhagic stroke by interviews at six-month intervals and reviews of medical records and computed tomographic scans.

RESULTS

Nineteen of 71 enrolled patients had recurrent hemorrhages during a mean follow-up period of 23.9+/-14.8 months, yielding a 2-year cumulative rate of recurrence of 21 percent. The apolipoprotein E genotype was significantly associated with the risk of recurrence. Carriers of the epsilon2 or epsilon4 allele had a two-year rate of recurrence of 28 percent, as compared with only 10 percent for patients with the common apolipoprotein E epsilon3/epsilon3 genotype (risk ratio, 3.8; 95 percent confidence interval, 1.2 to 11.6; P=0.01). Early recurrence occurred in eight patients, four of whom had the uncommon epsilon2/epsilon4 genotype. Also at increased risk for recurrence were patients with a history of hemorrhagic stroke before entry into the study (two-year recurrence, 61 percent; risk ratio, 6.4; 95 percent confidence interval, 2.2 to 18.5; P<0.001).

CONCLUSIONS

The apolipoprotein E genotype can identify patients with lobar intracerebral hemorrhage who are at highest risk for early recurrence. This finding makes possible both the provision of prognostic information to patients with lobar hemorrhage and a method of targeting and assessing potential strategies for prevention.

Donepezil therapy in clinical practice: a randomized crossover study

OBJECTIVE

To determine the efficacy of donepezil hydrochloride for the treatment of Alzheimer disease in patients drawn from clinical practice.

DESIGN

Two-center, randomized, placebo-controlled, double-masked crossover study.

SETTING

Memory disorders units at Massachusetts General and Brigham and Women's hospitals, Boston.

PATIENTS

Sixty individuals (30 men and 30 women; mean +/- SD age, 75.0+/-9.5 years) with probable Alzheimer disease and scores of 20 or less on the information-memory-concentration subscale of the Blessed Dementia Scale.

INTERVENTIONS

Placebo wash-in, followed in randomized sequence by (1) donepezil hydrochloride therapy, 5 mg/d, for 6 weeks, followed by placebo washout for 6 weeks and (2) placebo treatment for 6 weeks.

PRIMARY OUTCOME MEASURE

Change in Alzheimer's Disease Assessment Scale cognitive subscale scores from the beginning to the end of the two 6-week treatment periods.

RESULTS

Among patients completing treatment and testing for both periods (n = 48), subscale scores improved (mean +/- SEM) 2.17+/-0.98 points (95% confidence interval, 0.20-4.10 points) during donepezil therapy relative to placebo therapy (P = .04). Scores returned toward baseline within 3 weeks of drug washout. There was no associated change in caregiver-rated global impression (donepezil vs placebo: proportion improved, 0.24 vs 0.22; proportion worsened, 0.27 vs 0.35; P = .34) or on specific tests of explicit memory or verbal fluency. Contrary to studies with tacrine, the presence of the apolipoprotein E epsilon4 allele did not predict donepezil treatment failure. Most common adverse events related to donepezil therapy were nausea (5 patients), diarrhea (3 patients), and agitation (3 patients). Serious events possibly related to drug use were seizure, pancreatitis, and syncope (1 patient each).

CONCLUSION

This independent confirmation of data from phase 3 trials suggests that donepezil therapy modestly improves cognition in patients with Alzheimer disease who are encountered in clinical practice.

MRI detection of new hemorrhages: potential marker of progression in cerebral amyloid angiopathy

The authors used serial gradient-echo MRIs to detect new small hemorrhages in patients with previous lobar hemorrhage. Of 24 lobar hemorrhage patients (17 diagnosed with probable and 7 with possible amyloid angiopathy) who prospectively underwent repeat MRI 1.5 years after initial study, 9 (38%) demonstrated additional hemorrhages at follow-up. Interrater agreement was high. New hemorrhages were more frequent in patients with probable amyloid angiopathy (8 of 17, 47%) with more hemorrhages at baseline (p < 0.01). These results suggest a role for gradient-echo MRI in assessing disease progression in amyloid angiopathy.