Subcycle Optical Response Caused by a Terahertz Dressed State with Phase-Locked Wave Functions.

The coherent interaction of light with matter imprints the phase information of the light field on the wave function of the photon-dressed electronic state. A driving electric field, together with a stable phase that is associated with the optical probe pulses, enables the role of the dressed state in the optical response to be investigated. We observed optical absorption strengths modulated on a subcycle time scale in a GaAs quantum well in the presence of a multicycle terahertz driving pulse using a near-infrared probe pulse. The measurements were in good agreement with the analytical formula that accounts for the optical susceptibilities caused by the dressed state of the excitons, which indicates that the output probe intensity was coherently reshaped by the excitonic sideband emissions.

Lower prevalence of silent brain infarcts in the physically active: the Northern Manhattan Study.

OBJECTIVE: To examine the independent association between physical activity and subclinical cerebrovascular disease as measured by silent brain infarcts (SBI) and white matter hyperintensity volume (WMHV). METHODS: The Northern Manhattan Study (NOMAS) is a population-based prospective cohort examining risk factors for incident vascular disease, and a subsample underwent brain MRI. Our primary outcomes were SBI and WMHV. Baseline measures of leisure-time physical activity were collected in person. Physical activity was categorized by quartiles of the metabolic equivalent (MET) score. We used logistic regression models to examine the associations between physical activity and SBI, and linear regression to examine the association with WMHV. RESULTS: There were 1,238 clinically stroke-free participants (mean age 70 ± 9 years) of whom 60% were women, 65% were Hispanic, and 43% reported no physical activity. A total of 197 (16%) participants had SBI. In fully adjusted models, compared to those who did not engage in physical activity, those in the upper quartile of MET scores were almost half as likely to have SBI (adjusted odds ratio 0.6, 95% confidence interval 0.4-0.9). Physical activity was not associated with WMHV. CONCLUSIONS: Increased levels of physical activity were associated with a lower risk of SBI but not WMHV. Engaging in moderate to heavy physical activities may be an important component of prevention strategies aimed at reducing subclinical brain infarcts.

Clinical features of non-hypertensive lobar intracerebral hemorrhage related to cerebral amyloid angiopathy.

BACKGROUND AND PURPOSE: The present study aims to clarify the clinical features of non-hypertensive cerebral amyloid angiopathy-related lobar intracerebral hemorrhage (CAA-L-ICH). METHODS: We investigated clinical, laboratory, and neuroimaging findings in 41 patients (30, women; 11, men) with pathologically supported CAA-L-ICH from 303 non-hypertensive Japanese patients aged >OR=55, identified via a nationwide survey as symptomatic CAA-L-ICH. RESULTS: The mean age of patients at onset of CAA-L-ICH was 73.2 +/- 7.4 years; the number of patients increased with age. The corrected female-to-male ratio for the population was 2.2, with significant female predominance. At onset, 7.3% of patients received anti-platelet therapy. In brain imaging studies, the actual frequency of CAA-L-ICHs was higher in the frontal and parietal lobes; however, after correcting for the estimated cortical volume, the parietal lobe was found to be the most frequently affected. CAA-L-ICH recurred in 31.7% of patients during the average 35.3-month follow-up period. The mean interval between intracerebral hemorrhages (ICHs) was 11.3 months. The case fatality rate was 12.2% at 1 month and 19.5% at 12 months after initial ICH. In 97.1% of patients, neurosurgical procedures were performed without uncontrollable intraoperative or post-operative hemorrhage. CONCLUSIONS: Our study revealed the clinical features of non-hypertensive CAA-L-ICH, including its parietal predilection, which will require further study with a larger number of patients with different ethnic backgrounds.

Iodine-123-MIBG sympathetic imaging in Lewy-body diseases and related movement disorders.

Iodine-123-labeled metaiodobenzylguanidine (MIBG) has a history of over 20 years as a marker of myocardial sympathetic activity in Japan and has been used for various cardiac diseases. Aside from conventional utilities in patients with cardiac diseases, including ischemic heart diseases, cardiomyopathy, heart failure and diabetes, neurological disorders have recently been drawing special attention. The [(123)I]MIBG study showed markedly decreased myocardial uptake in Parkinson's disease, dementia with Lewy bodies and pure autonomic failure, which is a common feature of Lewy-body diseases. The MIBG study can be used for differentiating patients with extrapyramidal signs and dementia. The unique application of MIBG in movement disorders and related neurological diseases is one of its most common uses in Japan, and further studies are expected worldwide.

Prevalence and determinants of subclinical brain infarction: the Northern Manhattan Study.

OBJECTIVE: Risk factors for subclinical brain infarcts (SBI) have not been well studied, especially in Hispanic and black populations who may be at higher risk for vascular disease. We examined the prevalence and determinants of SBI in a multiethnic community cohort. METHODS: The Northern Manhattan Study (NOMAS) includes 892 stroke-free participants who underwent brain MRI. Baseline demographic and vascular risk factor data were collected. The presence of SBI was determined from the size, location, and imaging characteristics of the lesion based on fluid attenuated inversion recovery (FLAIR) T1 and T2, and proton density MRI sequences. We calculated the prevalence of SBI and cross-sectional associations with sociodemographic and vascular risk factors, using logistic regression to adjust for relevant covariates. RESULTS: Among 892 subjects (mean age 71.3 years), 158 (17.7%) had SBI (13.5% had 1 lesion, 4.3% had >1 lesion). Of the total 216 infarcts, most were small (<1 cm, 82.4%) and subcortical (82.9%). SBI prevalence increased with age (<65: 9.7%; 65 to 75: 16.4%; >75: 26.1%), was increased among men (21.3% vs 15.2% in women), and was increased among blacks (24.0% vs 18.1% in whites and 15.8% in Hispanics). The presence of SBI was independently associated with older age (per year: OR 1.06, 95% CI 1.04 to 1.09), male sex (OR 1.79, 95% CI 1.22 to 2.61), and hypertension (OR 2.08, 95% CI 1.35 to 3.22) adjusting for age, sex, race-ethnicity, and vascular risk factors. A significant interaction (p = 0.002) between race and age was observed such that younger black subjects had greater odds of having SBI. CONCLUSIONS: SBI were detected in nearly 18% of subjects in a multiethnic community-based cohort. Age, male sex, and hypertension were independently associated with SBI. Subclinical cerebral infarcts are more prevalent than symptomatic infarcts and may increase the true public health burden of stroke.

T-shaped GaAs quantum-wire lasers and the exciton Mott transition.

T-shaped GaAs quantum-wire (T-wire) lasers fabricated by the cleaved-edge overgrowth method with molecular beam epitaxy on the interface improved by a growth-interrupt high-temperature anneal are measured to study the laser device physics and fundamental many-body physics in clean one-dimensional (1D) systems. A current-injection T-wire laser that has 20 periods of T-wires in the active region and a 0.5 mm long cavity with high-reflection coatings shows a low threshold current of 0.27 mA at 30 K. The origin of the laser gain above the lasing threshold is studied with the high-quality T-wire lasers by means of optical pumping. The lasing energy is about 5 meV below the photoluminescence (PL) peak of free excitons, and is on the electron-hole (e-h) plasma PL band at a high e-h carrier density. The observed energy shift excludes the laser gain due to free excitons, and it suggests a contribution from the e-h plasma instead. A systematic micro-PL study reveals that the PL evolves with the e-h density from a sharp exciton peak, via a biexciton peak, to an e-h-plasma PL band. The data demonstrate an important role of biexcitons in the exciton Mott transition. Comparison with microscopic theories points out some problems in the picture of the exciton Mott transition.

Extent and distribution of white matter hyperintensities in normal aging, MCI, and AD.

OBJECTIVE: To analyze the extent and spatial distribution of white matter hyperintensities (WMH) in brain regions from cognitively normal older individuals (CN) and patients with mild cognitive impairment (MCI) and Alzheimer disease (AD). METHODS: We studied 26 mild AD, 28 MCI, and 33 CN. MRI analysis included quantification of WMH volume, nonlinear mapping onto a common anatomic image, and spatial localization of each WMH voxel to create an anatomically precise frequency distribution map. Areas of greatest frequency of WMH from the WMH composite map were used to identify 10 anatomic regions involving periventricular areas and the corpus callosum (CC) for group comparisons. RESULTS: Total WMH volumes were associated with age, extent of concurrent vascular risk factors, and diagnosis. After correcting for age, total WMH volumes remained significantly associated with diagnosis and extent of vascular risk. Regional WMH analyses revealed significant differences in WMH across regions that also differed significantly according to diagnosis. In post-hoc analyses, significant differences were seen between CN and AD in posterior periventricular regions and the splenium of the CC. MCI subjects had intermediate values at all regions. Repeated measures analysis including vascular risk factors in the model found a significant relationship between periventricular WMH and vascular risk that differed by region, but regional differences according to diagnosis remained significant and there was no interaction between diagnosis and vascular risk. CONCLUSIONS: Differences in white matter hyperintensities (WMH) associated with increasing cognitive impairment appear related to both extent and spatial location. Multiple regression analysis of regional WMH, vascular risk factors, and diagnosis suggest that these spatial differences may result from the additive effects of vascular and degenerative injury. Posterior periventricular and corpus callosum extension of WMH associated with mild cognitive impairment and Alzheimer disease indicate involvement of strategic white matter bundles that may contribute to the cognitive deficits seen with these syndromes.

Value of 123I-MIBG radioactivity in the differential diagnosis of DLB from AD.

OBJECTIVE: To evaluate the diagnostic reliability of cardiac iodine-123 metaiodobenzylguanidine ((123)I-MIBG) radioactivity in discriminating dementia with Lewy bodies (DLB) from Alzheimer disease (AD) regardless of parkinsonism. BACKGROUND: The diagnosis of DLB may be confounded by the absence of parkinsonism. This highlights the need to improve the accuracy of antemortem diagnosis of DLB without parkinsonism. METHODS: Cardiac sympathetic denervation was examined using myocardial (123)I-MIBG scintigraphy in 37 patients with DLB, 42 patients with AD, and 10 normal elderly controls. The DLB patients consisted of seven patients without parkinsonism (DLB/P-) and 30 patients with parkinsonism (DLB/P+) at the time of the study. RESULTS: The heart-to-mediastinum uptake ratio (H/M ratio) of myocardial MIBG uptake was decreased in both the DLB groups vs the AD group (p < 0.0001) and control group (p < 0.0001). The washout rate (WR) was higher in the DLB group than in the control group (p < 0.0001) and AD group (p < 0.0001). No differences were found between the AD and control groups or between the DLB/P+ and DLB/P- groups in either the early or delayed H/M ratio or WR. In discriminating between DLB and AD, regardless of parkinsonism, the delayed H/M ratio had a sensitivity of 100%, a specificity of 100%, and a positive predictive value of 100% at a cutoff value of 1.68. CONCLUSIONS: Our results indicate that dementia with Lewy bodies results in cardiac sympathetic denervation and that iodine-123 metaiodobenzylguanidine myocardial scintigraphy is a sensitive tool for discriminating dementia with Lewy bodies from Alzheimer disease even in patients without parkinsonism.

A clinical role for [(123)I]MIBG myocardial scintigraphy in the distinction between dementia of the Alzheimer's-type and dementia with Lewy bodies.

OBJECTIVE: Scintigraphy with [(123)I]metaiodobenzyl guanidine ([(123)I]MIBG) enables the quantification of postganglionic sympathetic cardiac innervation. Recently, myocardial [(123)I]MIBG scintigraphy has been found to be useful in distinguishing Parkinson's disease, a Lewy body disease, from other akinetic rigid syndromes. Some patients initially diagnosed with dementia of the Alzheimer's type (DAT) are discovered to have an alternative disease such as dementia with Lewy bodies (DLB), despite the application of stringent diagnostic criteria. In the present study, examinations were performed to clarify the usefulness of myocardial [(123)I]MIBG scintigraphy in improving the differential diagnosis between patients with DLB and DAT. METHODS: Fourteen patients with DLB and 14 patients with DAT underwent scintigraphy with [(123)I]MIBG, combined with orthostatic tests and cardiac examinations. RESULTS: In all patients with DLB, the heart to mediastinum (H/M) ratio of MIBG uptake was pathologically impaired in both early and delayed images, independently of the duration of disease and autonomic failure. All patients with DAT had successful MIBG uptake in the heart regardless of duration of disease and autonomic failure. Orthostatic hypotension was seen in four patients with DAT and 13 patients with DLB. CONCLUSIONS: [(123)I]MIBG myocardial scintigraphy might detect early disturbances of the sympathetic nervous system in DLB and might provide useful diagnostic information to discriminate DLB from DAT. The distinction between DLB and DAT may be improved by greater emphasis on cardiac sympathetic disturbances.

Peripheral sympathetic dysfunction in patients with Parkinson's disease without autonomic failure is heart selective and disease specific. taki@med.kanazawa-u.ac.jp.

UNLABELLED: The study was undertaken to investigate by means of iodine-123-labelled metaiodobenzylguanidine (MIBG) scintigraphy the peripheral sympathetic function in patients with Parkinson's disease (PD) without autonomic failure and in patients with related neurodegenerative diseases with parkinsonism. Seventy patients (33 men and 37 women, mean age 63+/-9.7 years) with parkinsonism and ten control subjects underwent MIBG scintigraphy. Of these 70 patients, 41 were diagnosed as having idiopathic PD, 9 multiple system atrophy (MSA), 6 progressive supranuclear palsy (PSP) and 2 corticobasal degeneration (CBD); the remaining 12 were diagnosed as having neurodegenerative disease with parkinsonism (P-nism) that did not meet the diagnostic criteria of any specific disease. Cardiac planar and tomographic imaging studies and subsequent whole-body imaging were performed 20 min and 3 h after the injection of 111 MBq MIBG. The early MIBG heart to mediastinum (H/M) ratio in PD (1.61+/-0.29) was significantly lower than that in the control group (2.24+/-0.14, P<0.01), P-nism (2.15+/-0.31, P<0.01), MSA (2.08+/-0.31, P<0.05) and PSP (2.30+/-0.24, P<0.01). The delayed H/M ratio in PD (1.47+/-0.34) was also significantly lower than that in the control group (2.37+/-0.14, P<0.01), P-nism (2.13+/-0.38, P<0.01), PSP (2.36+/-0.36, P<0.01) and MSA (2.17+/-0.36, P<0.01). In patients with PD, early and delayed H/M ratios were significantly decreased in disease stages I, II and III (established using the Hoehn and Yahr criteria) as compared with control subjects, and there were no significant differences among the stages. Only PD showed a significantly higher washout rate (WR) than that in the control subjects (27%+/-8.0% vs. 11%+/-4.2%, P<0.01). Early and delayed uptake ratios of the lung, parotid gland, thyroid gland, liver and femoral muscles in each of the patient groups were not significantly different from those in control subjects. Only the early and delayed uptake ratios of the lower leg muscles in MSA were significantly lower than those in the control group (P<0.05). IN CONCLUSION: In patients with PD without autonomic failure, only cardiac MIBG uptake was severely reduced in the earliest phase of the disease (stage I). Parkinsonian syndromes other than PD did not demonstrate significant reduction in MIBG uptake in any organs except for the lower legs in MSA. In patients with PD without autonomic failure, reduction in MIBG uptake occurs selectively in the heart; this is considered to be a specific finding for PD and useful for the differential diagnosis of the parkinsonian syndromes.

[Iodine-123-labeled meta-iodobenzylguanidine myocardial scintigraphy evaluation of Machado-Joseph disease].

Iodine-123-labeled meta-iodobenzylguanidine ([123I]MIBG), an analogue of guanetidine, is used as a tracer for evaluation of the function of sympathetic neurons. To investigate cardiac sympathetic function in Machado-Joseph disease (MJD), [123I] MIBG myocardial scintigraphy was performed in 12 patients with MJD and 20 controls. In planar imaging studies, the heart to the mediastinum of the average count ratio (H/M) was calculated for both early and delayed images. The mean values of H/M in delayed images of MJD was lower than those of controls (p < 0.01), but this did not correlate with duration of the illness. The mean values of H/M in MJD patients with abnormal sympathetic skin response (SSR) was lower than that with normal SSR (p < 0.05). The decrease of H/M in delayed image is more sensitive than abnormal SSR. The increase of heart rate after standing in the patients with low H/M was lower than those with normal H/M. Abnormal cardiac sympathetic function revealed by [123I]MIBG myocardial scintigraphy in MJD can be seen earlier than abnormal sudomotor system detected by SSR.

Decreased myocardial accumulation of 123I-meta-iodobenzyl guanidine in Parkinson's disease.

The aim of this study was to evaluate 123I-meta-iodobenzyl guanidine (123I-MIBG) myocardial scintigraphy in patients with Parkinson's disease as a way of detecting cardiac sympathetic dysfunction, and comparing the stage of disease and intensity of drug treatment with accumulation of 123I-MIBG. 123I-MIBG myocardial scintigraphy was performed in 48 patients with Parkinson's disease and 25 control subjects. In the planar imaging studies, the data acquisition matrix was 256 x 256 and the preset time was 5 min. The heart-to-mediastinum (H/M) average count ratio was calculated for both early (15 min) and delayed (3-4 h) images after 123I-MIBG injection (111 MBq). The mean H/M ratio in patients with Parkinson's disease was significantly lower than that in the controls (P < 0.0001). Regardless of disease severity, intensity of anti-Parkinson treatment and the presence or absence of orthostatic hypotension, the mean H/M ratios were always low in the Parkinsonian patients. Parkinson's disease may result in a severe abnormality of cardiac sympathetic function which has not been detected by previous cardiovascular autonomic studies.

Differentiation of idiopathic Parkinson's disease from striatonigral degeneration and progressive supranuclear palsy using iodine-123 meta-iodobenzylguanidine myocardial scintigraphy.

Iodine-123 meta-iodobenzylguanidine ([123I]MIBG), an analogue of norepinephrine, is a tracer for functioning of sympathetic neurons. To investigate cardiac sympathetic function in PD, SND, and PSP, [123I]MIBG myocardial scintigraphy was performed in 25 patients with PD, 15 patients with SND, 14 patients with PSP, and 20 control subjects. In planar imaging studies, the heart-to-mediastinum average count ratio (H/M) was calculated for both early and delayed images. The mean value of H/M in patients with PD was significantly lower than those with SND, PSP, or no disease. Regardless of disease severity or intensity of anti-Parkinsonian pharmacotherapy, mean values for H/M were always low in patients with PD. The mean value of H/M in SND with orthostatic hypotension (OH) was lower than that in SND without OH. Although the mean value of H/M in PSP with amitriptyline treatment was significantly lower than that in PSP patients without amitriptyline treatment, there was no significant difference between the mean value of H/M in PSP patients without amitriptyline treatment and that in control. Thus, PD may have a abnormality of cardiac sympathetic function which has not been detected by previous cardiovascular autonomic studies. Moreover, particularly in early stages, [123I]MIBG myocardial scintigraphy may provide helpful diagnostic information in these akinetic-rigid syndromes.

[Iodine 123-labeled meta-iodobenzylguanidine myocardial scintigraphy in the cases of idiopathic Parkinson's disease, multiple system atrophy, and progressive supranuclear palsy].

A 20-25% rate of antemortem misdiagnosis of idiopathic Parkinson's disease (PD) suggests that it may be difficult to clinically differentiate PD from other degenerative diseases of the central nervous system, such as progressive supranuclear palsy (PSP) or multiple system atrophy (MSA). Iodine-123 meta-iodobenzylguanidine ([123I] MIBG), an analogue of norepinephrine, is a tracer for functioning of sympathetic neurons. To investigate cardiac sympathetic function in PD, MSA, and PSP, [123I] MIBG myocardial scintigraphy was performed in 25 patients with PD, 25 patients with MSA, 14 patients with PSP, and 20 control subjects. In planar imaging studies, the heart-to-mediastinum average count ratio (H/M) was calculated for both early and delayed images. The mean value of H/M in patients with PD was significantly lower than in those with MSA, PSP, or no disease (p < 0.0001). Regardless of disease severity or intensity of anti-parkinsonian pharmacotherapy, mean values for H/M were always low in patients with PD. The mean values of H/M in patients with MSA and PSP were significantly lower than in controls (p < 0.01). There was no significant difference between the mean value of H/M in MSA with orthostatic hypotension (OH) and that in MSA without OH, and also there was no significant difference between the mean value of H/M in MSA with striatonigral degeneration and that in MSA with olivopontocerebellar atrophy. Although the mean value of H/M in PSP with amitriptyline treatment was significantly lower than that in PSP patients without amitriptyline treatment (p < 0.005), there was no significant difference between the mean value of H/M in PSP patients without amitriptyline treatment and that in controls. There was no correlation between H/M and disease duration in those three akinetic-rigid disorders that we have studied here. Thus, PD may have an abnormality of cardiac sympathetic function which has not been detected by previous cardiovascular autonomic studies. Particularly in early stages, [123I] MIBG myocardial scintigraphy may help to differentiate PD from MSA and PSP.