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PubMed2003

MRI study of white matter diffusion anisotropy in schizophrenia.

Diffusion tensor imaging (DTI) can provide information about brain white matter integrity. The results of DTI studies in schizophrenia are somewhat variable and could benefit from standardized image processing methods. Fourteen patients with schizophrenia or schizoaffective disorder and 14 healthy volunteers underwent DTI. Scans were analyzed using a rigorous voxelwise approach. The key dependent variable, fractional anisotropy, was lower for patients in the corpus callosum, left superior temporal gyrus, parahippocampal gyri, middle temporal gyri, inferior parietal gyri, medial occipital lobe, and the deep frontal perigenual region. Regions showing reduced white matter fractional anisotropy are known to be abnormal in schizophrenia. The voxelwise method used in the current study can provide the basis for hypothesis-driven research.

Adult↗
PubMed2004

Sputter-depth profiling for thin-film analysis.

Following a brief historical background, the concepts and the present state of sputter-depth profiling for thin-film analysis are outlined. There are two main branches: either the removed matter (as in mass- or optical-spectroscopy-based secondary-ion mass spectrometry or glow-discharge optical emission spectroscopy), or the remaining surface (as in Auger electron spectroscopy and X-ray photoelectron spectroscopy) is characterized. These complementary methods show the same result if there is no preferential sputtering of a component. The common root of both is the fundamental ion-solid interaction. Understanding of how the latter influences the depth resolution has led to important improvements in experimental profiling conditions such as sample rotation and the use of low-energy ions at glancing incidence. Modern surface-analysis instruments can provide high-resolution depth profiles on the nanometre scale. Mathematical models of different sophistication were developed to allow deconvolution of the measured profile or quantification by reconstruction of the in-depth distribution of composition. For the latter purpose, the usefulness of the so-called mixing-roughness-information (MRI) depth model is outlined on several thin-film structures (e.g. AlAs/GaAs and Si/Ge), including its extension to quantification of sputter-depth profiles in layer structures with preferential sputtering of one component (Ta/Si). Using the MRI model, diffusion coefficients at interfaces as low as 10(-22) m(2) s(-1) can be determined. Fundamental limitations of sputter-depth profiling are mainly traced back to the stochastic nature of primary-particle energy transfer to the sputtered particle, promoting atomic mixing and the development of surface roughness. Owing to more sophisticated experimental methods, such as low-energy cluster ion bombardment, glancing ion incidence or 'backside' sputtering, these ultimate limitations can be reduced to the atomic monolayer scale.

Journal Article↗
PubMed2025

The cellular associates of late life changes in white matter microstructure.

The microstructural architecture of white matter supporting information flow across local circuits and large-scale networks changes throughout the lifespan. However, the genetic and cellular factors underlying age-related variations in white matter microstructure have yet to be established. Here, we examined the genetic associates of individual differences in diffusion-based measures of white matter in a population-based cohort (N=29,862) from the UK Biobank. Estimates of heritability from Genome-Wide Association Study (GWAS) data revealed that genetic factors are linked to population variability in 96.1% of 432 tract microstructural measures. The presence of shared genetic influences was observed to be greater within, relative to between, broad tract classes (commissural, association, projection, and complex cerebellar). Age associations with microstructural changes were estimated across diffusivity measures, with association class tracts showing the greatest vulnerability to age-related decline in older adults. Analyses of imputed cellular associates of age-related changes in white matter revealed a preferential relationship with cell gene markers of oligodendrocytes and other glial cell types, with sparse relationships observed for inhibitory and excitatory cells. These data indicate that white matter tract microstructure is shaped by genetic factors and suggest a role for glial cell-related transcripts in late-life changes in the structural wiring properties of the human brain.

Aging↗
PubMed2006

Severe cortical involvement in MV2 Creutzfeldt-Jakob disease: an autopsy case report.

MV2 type sporadic Creutzfeldt-Jakob disease (sCJD) is reported to have a long duration and marked involvement of the cerebral deep gray matter. We describe an autopsied long-surviving sCJD case of MV2. In the early stages, the patient exhibited memory impairment, attention deficit and semantic memory disorder. Diffusion-weighted MRI showed abnormal hyperintensity signals along the cerebral cortex, sparing the thalami and basal ganglia. Pathological observations included: severe spongiosis throughout the cerebral cortex, several kuru plaques and plaque-like PrP deposits in the cerebellum, with only minimal degeneration in the thalami and basal ganglia. Our case suggests that MV2 has a wide clinicopathological spectrum, which ranges from "VV2" to "MM2" type.

Aged↗
PubMed1992

Giant axonal neuropathy with predominant central nervous system manifestations.

The authors describe a 25-year-old woman with giant axonal neuropathy (GAN) and severe CNS involvement. She had been admitted to hospital with generalized seizures, and had gait disturbances followed by progressive mental deterioration since childhood. Neurological examination revealed mental retardation, scanning speech, cerebellar dysfunction, pyramidal signs, mainly in the lower extremities, and peripheral sensory neuropathy. Sensory nerve conduction velocity was decreased; brain CT and MRI showed diffuse demyelination. Sural nerve biopsy revealed characteristic signs of GAN. The patient's older sister had died at the age of 23, after having had similar neurological disturbances since childhood. This case illustrates an unfamiliar presentation of GAN, characterized by mild sensory neuropathy and serve CNS involvement, including seizures.

Adult↗
PubMed1995

Familial mitochondrial encephalomyopathy with deaf-mutism, ophthalmoplegia and leukodystrophy.

We report two sisters (32 and 36 years old) with familial deaf-mutism, progressive external ophthalmoplegia, leukodystrophy and mitochondrial myopathy. T2-weighted brain MRI demonstrated diffuse symmetrical high intensity areas in the white matter. Their muscle biopsies showed ragged-red fibers and cytochrome c oxidase (CCO)-negative fibers. CCO activity in biopsied muscle decreased to about 20% of normal control. They had no deletions of the mitochondrial DNA and no point mutations in mitochondrial tRNA. Their brother was diagnosed as having Kugelberg-Welander disease, grand mal seizures and urinary dysfunction. Their parents and grandparents had consanguinity. Three relatives were found to have deaf-mutism without accompanying ophthalmoplegia. This rare combination of mitochondrial encephalomyopathy and familial deaf-mutism might be caused by a nuclear DNA mutation in these sisters.

Adult↗
PubMedDate not supplied

Region specific modeling of cardiac muscle: comparison of simulated and experimental potentials.

This article investigates the quantitative predictive capabilities of region-specific models by comparing experimental electrograms obtained from in vivo mapping of the ventricular free wall with those obtained through simulation of a region specific three-dimensional bidomain model that incorporates measured fiber orientations. Epicardial electrograms were recorded from canine left ventricles during and after unipolar pacing using a 528-channel electrode plaque. Fiber directions throughout the tissue were estimated from diffusion-weighted MRI and from pace mapping. Electrograms were computed in the bidomain model with experimentally derived properties during paced activations at the same spatiotemporal resolution as those recorded experimentally. Epicardial potentials from model and experiment were directly compared, and sensitivities of these comparisons to reference electrode location and to the choice of material properties were analyzed. The comparisons performed here demonstrate, that (1) the stimulus artifact can be used to estimate the in vivo myocardial fiber architecture, (2) the correlation between simulated and experimental electrograms decreases with increasing pacing depth, and (3) the quantitative comparisons between bidomain model and experimental data are sensitive to both the description of the fiber architecture, and the location of the unipolar reference electrode, but relatively insensitive to moderate changes in the bidomain conductivities.

Animals↗
PubMed2005

Giant axonal neuropathy: clinical and genetic study in six cases.

BACKGROUND: Giant axonal neuropathy (GAN) is a severe recessive disorder characterised by variable combination of progressive sensory motor neuropathy, central nervous system (CNS) involvement, and "frizzly" hair. The disease is caused by GAN gene mutations on chromosome 16q24.1. AIMS: To search for GAN gene mutations in Turkish patients with GAN and characterise the phenotype associated with them. METHODS: Linkage and mutation analyses were performed in six affected patients from three consanguineous families. These patients were also investigated by cranial magnetic resonance imaging (MRI) and electroencephalography (EEG). Electromyography (EMG) was performed in heterozygous carriers from family 1 and family 3. RESULTS: Linkage to 16q24.1 was confirmed by haplotype analysis. GAN mutations were identified in all families. Family 1 had the R293X mutation, previously reported in another Turkish family. Families 2 and 3, originating from close geographical areas, shared a novel mutation, 1502+1G>T, at the donor splice site of exon 9. All patients displayed a common phenotype, including peripheral neuropathy, cerebellar ataxia, and frizzly hair. Cranial MRI showed diffuse white matter abnormalities in two patients from family 1 and the patient from family 3, and minimal white matter involvement in the patient from family 2. EMG of a heterozygous R293X mutation carrier showed signs of mild axonal neuropathy, whereas a 1502+1G>T mutation carrier had normal EMG. EEG abnormalities were found in three patients. CONCLUSION: These findings highlight the association of CNS involvement, in particular white matter abnormalities, with peripheral neuropathy in GAN. The phenotypical consequences of both mutations (when homozygous) were similar.

Adolescent↗
PubMed1998

A unique familial leukodystrophy with adult onset dementia and abnormal glycolipid storage: a new lysosomal disease?

Two adult siblings with early onset dementia are described. At presentation, in their early 30s, they showed poor judgment and disinhibition. A progressive dementia ensued over several years. Brain MRI disclosed diffusely increased T2 signal in the cerebral white matter, suggestive of a leukodystrophy. Numerous lysosomal enzyme assays including leucocyte arylsulphatase A and galactocerebrosidase activities, plasma and fibroblast very long chain fatty acid concentrations, and urinary sulphatide concentrations were normal, as were CSF analyses. A brain biopsy disclosed periodic acid Schiff (PAS) and Sudan black positive material in perivascular macrophages which, by electron microscopy, consisted of stacks of straight or curvilinear paired membranes within angulate lysosomes, indicative of abnormal glycolipid accumulation. The combination of clinical, radiological, biochemical, and pathological features of this degenerative disease is not consistent with that of any of the known leukodystrophies or lysosomal storage disorders. These findings suggest a previously undescribed familial glycolipid storage disorder causing an adult onset leukodystrophy and presenting with behavioural symptoms that mimic a psychiatric disorder.

Adult↗
PubMed2007

Case reports of three patients showing optic nerve head melanocytoma and systemic hypertension.

PURPOSE: To report the association of optic disk melanocytoma with systemic hypertension. CASES: Ocular examination of 3 asymptomatic hypertensive patients revealed a pigmented lesion over the optic disk. After clinical examination and radiological evaluation a diagnosis of optic disk melanocytoma was made. One patient had a mild decrease in visual acuity associated with an increase in size of the lesion during the follow-up. Systemic evaluation revealed increased urinary vanillylmandelic acid in all the patients. MRI showed diffuse adrenal hyperplasia while a (131)I-MIBG scan showed increased uptake in 1 case. CONCLUSIONS: Optic disk melanocytoma is a benign tumor though the lesion may increase in size with the resultant decrease in visual acuity over few years. It may be associated with systemic hypertension secondary to increased levels of catecholamines in the body, which is related to the common neural crest origin of melanocytes, adrenal medullary cells and chromaffin cells.

Adult↗
PubMed2005

Acute and reversible cardiomyopathy provoked by stress in women from the United States.

BACKGROUND: A clinical entity characterized by acute but rapidly reversible left ventricular (LV) systolic dysfunction and triggered by psychological stress is emerging, with reports largely confined to Japan. METHODS AND RESULTS: Over a 32-month period, 22 consecutive patients with this novel cardiomyopathy were prospectively identified within a community-based practice in the Minneapolis-St. Paul, Minn, area. All patients were women aged 32 to 89 years old (mean 65+/-13 years); 21 (96%) were > or =50 years of age. The syndrome is characterized by (1) acute substernal chest pain with ST-segment elevation and/or T-wave inversion; (2) absence of significant coronary arterial narrowing by angiography; (3) systolic dysfunction (ejection fraction 29+/-9%), with abnormal wall motion of the mid and distal LV, ie, "apical ballooning"; and (4) profound psychological stress (eg, death of relatives, domestic abuse, arguments, catastrophic medical diagnoses, devastating financial or gambling losses) immediately preceding and triggering the cardiac events. A significant proportion of patients (37%) had hemodynamic compromise and required vasopressor agents and intra-aortic balloon counterpulsation. Each patient survived with normalized ejection fraction (63+/-6%; P<0.001) and rapid restoration to previous functional cardiovascular status within 6+/-3 days. In 95%, MRI identified diffusely distributed segmental wall-motion abnormalities that encompassed LV myocardium in multiple coronary arterial vascular territories. CONCLUSIONS: A reversible cardiomyopathy triggered by psychologically stressful events occurs in older women and may mimic evolving acute myocardial infarction or coronary syndrome. This condition is characterized by a distinctive form of systolic dysfunction that predominantly affects the distal LV chamber and a favorable outcome with appropriate medical therapy.

Acute Disease↗
PubMed2002

Acute stroke care in Illinois: a statewide assessment of diagnostic and treatment capabilities.

BACKGROUND AND PURPOSE: To define areas for quality improvement in acute stroke care, a statewide assessment of preparedness for acute stroke diagnosis and treatment was carried out among 202 acute receiving hospitals in Illinois. METHODS: Medical directors or their designees completed a 1-page survey form that addressed availability of personnel, diagnostic technology, and organized programs for the treatment of acute stroke patients at their facility. In the analysis, acute care receiving hospitals in the Greater Chicago Metropolitan Area (GCMA) (Cook, Dupage, Lake, Will, and Kane counties) were compared with those in the remainder of the state. RESULTS: Of the acute care receiving hospitals, 91% responded to the survey. Overall, 99% had an emergency room receiving facility, 98.3% had a CT scanner, and slightly >70% had a recombinant tissue plasminogen activator (r-TPA) protocol. We found that 93.2% of residents in Illinois lived in a county with at least 1 acute care facility with an r-TPA treatment protocol. However, many of the non-GCMA receiving hospitals did not have a neurologist or a neurosurgeon available. Furthermore, specialized stroke diagnostic technology (eg, transcranial Doppler, diffusion-weighted MRI, MR angiography) was generally lacking in both the GCMA and non-GCMA, as were stroke community awareness programs and acute care stroke teams. CONCLUSIONS: Stroke is a preventable and treatable disease. However, there are barriers to stroke care that are based on the availability of personnel, diagnostic technology, and programs. A systematic approach to the organization, implementation, and maintenance of services could improve outcome for stroke patients and reduce the public health burden of this deadly disease.

Acute Disease↗
PubMed2002

Acute ischemic stroke patterns in infective and nonbacterial thrombotic endocarditis: a diffusion-weighted magnetic resonance imaging study.

BACKGROUND AND PURPOSE: Although infective endocarditis (IE) and nonbacterial thrombotic endocarditis (NBTE) are associated with cardioembolic stroke, differences in the nature of these conditions may result in differences in associated stroke patterns. We compared patterns of acute and recurrent ischemic stroke in IE and NBTE, using diffusion-weighted MRI (DWI). METHODS: Using ICD-9 diagnostic codes and medical record review, we identified 362 patients (387 episodes) with IE and 14 patients with NBTE. Thirty-five patients (with 27 episodes of IE, 9 NBTE) who underwent 36 initial and 29 follow-up DWI scans were selected for this study. DWI lesion size, number, and location were compared between groups and correlated with stroke syndromes and endocarditis features. RESULTS: DWI was abnormal in all but 2 patients. Four acute stroke patterns were identified: (1) single lesion, (2) territorial infarction, (3) disseminated punctate lesions, and (4) numerous small (<10 mm) and medium (10 to 30 mm) or large (>30 mm) lesions in multiple territories. All patients with NBTE exhibited pattern 4, whereas those with IE exhibited patterns 1, 2, 3, and 4 (6, 2, 8 and 9 episodes, respectively). Seventy-five percent of patients with pattern 3 exhibited the clinical syndrome of embolic encephalopathy. Vegetation size, valve, and organisms had no correlation with stroke patterns. CONCLUSION: DWI has utility in differentiating between IE and NBTE. Patients with NBTE uniformly have multiple, widely distributed, small and large strokes, whereas patients with IE exhibit a panoply of stroke patterns.

Acute Disease↗
PubMed2002

Cerebral infarction due to carotid occlusion caused by cervical vagal neurilemmoma: report of a case.

BACKGROUND: We report a case of a 71-year-old woman with cerebral infarction due to occlusion of the internal carotid artery (ICA) caused by a neck tumor. CASE DESCRIPTIONS: In 1998, the patient complained of mild hoarseness, and a diagnostic workup showed a cervical mass that was considered a benign neck tumor. In September 2000, she developed right-sided weakness. Diffusion-weighted MRI showed a high-intensity area in the territory of the left middle cerebral artery. Carotid angiography and ultrasonography revealed occlusion of the left ICA, which was due to compression by the neck tumor. Superficial temporal artery-middle cerebral artery anastomosis was performed to prevent critical reduction of cerebral blood flow in the left ICA territory; this was followed by tumor resection. The occluded ICA recanalized after tumor resection. Microscopic examination showed that the tumor was a vagal neurilemmoma. CONCLUSIONS: This is the first case of cerebral infarction due to left ICA occlusion by a cervical neurilemmoma. Even when the neck tumor is benign, it may occlude the ICA and thereby cause cerebral infarction.

Aged↗
PubMed2003

Abciximab reduces monocyte tissue factor in carotid angioplasty and stenting.

BACKGROUND AND PURPOSE: Abciximab, a nonselective glycoprotein IIb/IIIa inhibitor, was shown to reduce peri-interventional stroke rate in carotid stenting. We evaluated the effect of adjunct abciximab therapy on monocyte-platelet cross talk and neurological deficit in unprotected carotid stenting and compared its efficacy with distal filter protection. METHODS: Fifty patients were randomized to either standard antithrombotic therapy (n=30) consisting of aspirin, clopidogrel, and heparin or adjunct bolus (0.25 mg/kg) and 12-hour infusion (0.125 microg x kg(-1) x min(-1)) of abciximab (n=20). A third cohort of patients was stented with filter protection (n=30). Monocyte-platelet aggregate formation and monocyte tissue factor expression were determined by whole blood flow cytometry, and F1.2 generation and soluble CD40 ligand (sCD40L) were determined by immunoassay. RESULTS: The incidence of peri-interventional ischemic episodes (23% versus 10%; P=0.2) and the number of de novo ischemic lesions detected by diffusion-weighted MRI (47% versus 30%; P=0.17) were not significantly different between standard antithrombotic therapy and adjunct abciximab but were reduced with filter protection (P=0.023). However, the number of transient ischemic attacks was lower (P=0.05) and the National Institutes of Health Stroke Score rapidly decreased in patients with adjunct abciximab. This clinical improvement was paralleled by a reduction in the postinterventional percentage of activated monocyte-platelet aggregates (CD62P+/CD14+; P=0.018) and the number of tissue factor-positive monocytes (TF+/CD14+; P=0.005). Both abciximab and filter protection suppressed F1.2 generation and significantly reduced sCD40L. CONCLUSIONS: Abciximab limits thrombus propagation and thrombus stabilization after carotid stenting by reducing monocyte-platelet cross talk and sCD40L. Although abciximab seems inferior to filter devices in peri-interventional cerebral protection, it may be considered in patients who do not allow placement of protection devices.

Abciximab↗
PubMed2003

Statewide assessment of hospital-based stroke prevention and treatment services in North Carolina: changes over the last 5 years.

BACKGROUND AND PURPOSE: The first published statewide assessment of stroke prevention and treatment services in the United States was carried out in North Carolina in 1998. The purpose of the present study was to measure changes in these services that may have occurred over the last 5 years. METHODS: A 1-page questionnaire was sent to each facility in the state in February 2003. RESULTS: Complete responses were obtained from each of the state's 128 facilities. The proportions of hospitals providing CT angiography (35% versus 55%, P<or=0.01), diffusion-weighted MRI (20% versus 45%, P<or=0.01), transesophageal echocardiography (45% versus 59%, P<or=0.02), and inpatient rehabilitation services (25% versus 43%, P<or=0.01) increased over the 5 years. There was a trend toward more facilities having tissue plasminogen activator protocols (43% versus 54%, P<or=0.09) but a decrease in the proportion of hospitals with interventional radiologists (23% versus 15%, P<0.01). There was no change in the proportion of the state's population living in a county with a basic stroke prevention and treatment center, with the proportion residing in a county with an advanced center increasing by 12%. Entire regions of the state lacked either type of center, and only 14% had even the essential infrastructure recommended for a Brain Attack Coalition-type primary stroke center. There was no difference in the proportions of hospitals with organized stroke teams, those having a stroke acute care unit, those using stroke care maps, or hospitals having community awareness programs. CONCLUSIONS: Certain technologies have become more widely available, but hospital investments in stroke-related programs have not appreciably increased.

Diagnostic Imaging↗
PubMed2005

Ataxic hemiparesis from strategic frontal white matter infarction with crossed cerebellar diaschisis.

BACKGROUND: Ataxic hemiparesis is a classic lacunar syndrome that most often localizes to the pons. RESULTS: We report 3 patients who presented with left-sided ataxic hemiparesis and were found on imaging to have small right frontal subcortical white matter infarcts in similar locations by diffusion-weighted MRI. [99mTc]hexamethylpropylenamine oxime single-photon emission computed tomography (SPECT) scans in all 3 patients showed decreased metabolism in the contralateral cerebellar hemisphere, indicative of crossed cerebellar diaschisis (CCD). CONCLUSIONS: CCD is under-recognized in ataxic hemiparesis and may have implications for functional recovery after this type of ischemic stroke.

Aged↗
PubMed2006

Why does acute hyperglycemia worsen the outcome of transient focal cerebral ischemia? Role of corticosteroids, inflammation, and protein O-glycosylation.

BACKGROUND AND PURPOSE: Hyperglycemia adversely affects the outcome of stroke. Global ischemia data support that the harmful effect of hyperglycemia is mediated by glucose-induced elevated plasma glucocorticoids. Here we sought to evaluate the negative effects of hyperglycemia on transient focal ischemia in the rat, and to test whether these could be prevented by inhibition of either corticosteroid production or neutrophil infiltration. METHODS: Sprague-Dawley rats (n=217) were used. Ischemia was induced by 1 hour middle cerebral artery occlusion (n=196). Acute hyperglycemia was induced by IP injection of dextrose 30 minutes before ischemia. Neutrophil infiltration was blocked by neutropenia with vinblastine. Corticosterone synthesis was inhibited by chemical adrenalectomy with metyrapone. We measured MRI lesion and tissue infarct volumes, evaluated the neurological function, brain myeloperoxidase and matrix metalloproteinase-9 activities, and protein O-glycosylation. RESULTS: Hyperglycemia significantly enhanced MRI diffusion-weighted imaging alterations, increased cortical, but not subcortical, infarct volume, worsened neurological score, and enhanced brain myeloperoxidase and matrix metalloproteinase-9 activities. Metyrapone did not prevent hyperglycemic brain damage despite successful reduction of plasma corticosterone. Yet, metyrapone tended to reduce cortical infarction and apparent diffusion coefficient lesion volume, indicating some negative contribution of corticosterone. Blocking neutrophil infiltration was also ineffective to prevent the harmful effect of hyperglycemia. A new finding was that O-linked glycosylation of cerebral proteins was increased under hyperglycemia. CONCLUSIONS: In transient middle cerebral artery occlusion, the hyperglycemia-exacerbated brain damage cannot be fully explained by the negative effects of plasma corticosteroids or neutrophil infiltration. The contribution of other intrinsic effects of high glucose, such as brain protein O-glycosylation, deserves further investigation.

Adrenal Cortex Hormones↗