Citations

Background and Purpose — The aim of the study was to evaluate the relationship between daily aspirin use and urinary excretion of a stable thromboxane metabolite, 11-dehydrothromboxane B 2 (11-DTB2), in African American stroke patients. Methods — Subjects were a subgroup of those screened for the African American Antiplatelet Stroke Prevention Study. Subjects were within 4 months of noncardioembolic ischemic stroke and were not being treated with anticoagulants. Antithrombotic therapy at the time of urine collection varied according to the practice patterns of various attending physicians who treated the patients during their acute strokes. 11-DTB2 was measured by enzyme immunoassay in random urine samples 1 to 4 months after the stroke. Results — Eighty-seven of 92 patients enrolled were able to give a urine sample at the time of enrollment. There were 51 men and 36 women aged 36 to 87 (mean 62) years. On the basis of antithrombotic treatment before the sample collection, we divided patients into 4 groups: (1) 16 patients treated with no aspirin (no antithrombotic drugs [n=4] or ticlopidine [n=12]), (2) 21 patients treated with 81 to 325 mg aspirin per day (81 mg/d [n=2], 325 mg/d [n=19]), (3) 20 patients treated with 650 mg aspirin per day, and (4) 30 patients treated with 975 to 1300 mg aspirin per day (975 mg/d [n=2] and 1300 mg/d [n=28]). In patients taking daily aspirin at any dose, the median urinary 11-DTB2 was 783 pg/mg creatinine compared with 1386 pg/mg creatinine in patients not taking daily aspirin ( P =0.01 by Wilcoxon rank sum test). In multivariate regression analysis, aspirin use remained significantly associated with lower urinary 11-DTB2 ( P =0.008). There was no dose-response effect between the 3 aspirin dose groups and urinary 11-DTB2 ( P =0.70). Conclusions — In African American stroke patients, aspirin use is associated with significantly lower urinary 11-DTB2 independent of other vascular factors, and there does not appear to be a dose-response effect for aspirin doses of 325 to 1300 mg daily. The clinical significance of these finding remains to be determined.

Background — Despite the common occurrence of aortic stenosis, the cellular causes of the disorder are unknown, in part because of the absence of experimental models. We hypothesized that atherosclerosis and early bone matrix expression in the aortic valve occurs secondary to experimental hypercholesterolemia and that treatment with atorvastatin modifies this transformation. Methods and Results — To test this hypothesis, we developed an experimental hypercholesterolemic rabbit model. New Zealand White rabbits (n=48) were studied: group 1 (n=16), normal diet; group 2 (n=16), 1% (wt/wt) cholesterol diet; and group 3 (n=16), 1% (wt/wt) cholesterol diet plus atorvastatin (3 mg/kg per day). The aortic valves were examined with hematoxylin and eosin stain, Masson trichrome, macrophage (RAM 11), proliferation cell nuclear antigen (PCNA), and osteopontin immunostains. Cholesterol and highly sensitive C-reactive protein (hsCRP) serum levels were obtained by standard assays. Computerized morphometry and digital image analysis were performed for quantifying PCNA (% area). Electron microscopy and immunogold labeling were performed for osteopontin. Semiquantitative RT-PCR was performed for the osteoblast bone markers [alkaline phosphatase, osteopontin, and osteoblast lineage-specific transcription factor ( Cbfa-1 )]. There was an increase in cholesterol, hsCRP, PCNA, RAM 11, and osteopontin and osteoblast gene markers (alkaline phosphatase, osteopontin, and Cbfa-1 ) in the cholesterol-fed rabbits compared with control rabbits. All markers except hsCRP were reduced by atorvastatin. Conclusions — These findings of increased macrophages, PCNA levels, and bone matrix proteins in the aortic valve during experimental hypercholesterolemia provide evidence of a proliferative atherosclerosis–like process in the aortic valve associated with the transformation to an osteoblast-like phenotype that is inhibited by atorvastatin.

ABSTRACTMurine Lyme borreliosis, caused by infection with the spirocheteBorrelia burgdorferi, results in acute arthritis and carditis that regress as a result ofB. burgdorferi-specific immune responses.B. burgdorferi-specific antibodies can attenuate arthritis in mice deficient in both B cells and T cells but have no effect on carditis. Because macrophages comprise the principal immune cell in carditis, T-cell responses that augment cell-mediated immunity may be important for carditis regression. To investigate this hypothesis, we examined the course of Lyme carditis in mice selectively deficient in B cells or αβ T cells. Our results show that carditis regresses in B-cell-deficient B10.Akmice but not in αβ T-cell-deficient mice, independently of the mouse strain background. Despite prominent macrophage infiltrates, hearts fromB. burgdorferi-infected αβ T-cell-deficient mice had less mRNA for tumor necrosis factor alpha as measured by reverse transcription-PCR compared to infected control mice. Anti-inflammatory cytokine mRNA levels were equivalent. Adoptive transfer of gamma interferon-secreting CD4+T cells into infected αβ T-cell-deficient mice promoted carditis resolution. These results show that αβ T cells can promote resolution of murine Lyme carditis and are the first demonstration of a beneficial role for CD4+T helper 1 cells in this disease.

Plasma Aβ42 (amyloid β42 peptide) is invariably elevated in early-onset familial Alzheimer's disease (AD), and it is also increased in the first-degree relatives of patients with typical late-onset AD (LOAD). To detect LOAD loci that increase Aβ42, we used plasma Aβ42 as a surrogate trait and performed linkage analysis on extended AD pedigrees identified through a LOAD patient with extremely high plasma Aβ. Here, we report linkage to chromosome 10 with a maximal lod score of 3.93 at 81 centimorgans close to D10S1225. Remarkably, linkage to the same region was obtained independently in a genome-wide screen of LOAD sibling pairs. These results provide strong evidence for a novel LOAD locus on chromosome 10 that acts to increase Aβ.

ABSTRACT The abnormal accumulation of the amyloid β protein (Aβ) has been implicated as an early and critical event in the etiology and pathogenesis of Alzheimer's disease (AD). Compounds that reduce Aβ accumulation may therefore be useful therapeutically. In cell‐based screens we detected a significant reduction in Aβ concentration after treatment with the phosphatidylinositol kinase inhibitors wortmannin and LY294002. To determine the effect of this class of compounds on in vivo Aβ accumulation, we administered wortmannin to the Tg2576 mouse model of AD. Oral administration of wortmannin over four months resulted in a significant, non‐overlapping 40%–50% reduction in the number of senile plaques, one of the pathological hallmarks of AD. Sandwich ELISA analysis of formic acid extractable Aβ in the brain of treated animals indicates that both Aβ40 and the longer, more amyloidogenic form of the peptide, Aβ42, were significantly reduced. These data provide the first direct evidence that compounds identified by their ability to reduce Aβ concentration in vitro can reduce Aβ accumulation and deposition in the brain, thus establishing a basic paradigm for the identification and evaluation of additional compounds that lower Aβ accumulation.

Peptides derived from proteolytic processing of the β-amyloid precursor protein (APP), including the amyloid-β peptide (Aβ), play a critical role in the pathogenesis of Alzheimer's dementia. We report that transgenic mice overexpressing APP and Aβ have a profound attenuation in the increase in neocortical blood flow elicited by somatosensory activation. The impairment is highly correlated with brain Aβ concentration and is reproduced in normal mice by topical neocortical application of exogenous Aβ1–40 but not Aβ1–42. Overexpression of M146L mutant presenilin-1 in APP mice enhances the production of Aβ1–42 severalfold, but it does not produce a commensurate attenuation of the hyperemic response. APP and Aβ overexpression do not diminish the intensity of neural activation, as reflected by the increase in somatosensory cortex glucose usage. Thus, Aβ-induced alterations in functional hyperemia produce a potentially deleterious mismatch between substrate delivery and energy demands imposed by neural activity.