Integrated approach to the data processing of four-dimensional datasets from phase-contrast x-ray tomography.

Phase contrast X-ray tomography (PCT) enables the study of systems consisting of elements with similar atomic numbers. Processing datasets acquired using PCT is nontrivial because of the low-pass characteristics of the commonly used single-image phase retrieval algorithm. In this study, we introduce an image processing methodology that simultaneously utilizes both phase and attenuation components of an image obtained at a single detector distance. This novel method, combined with regularized Perona-Malik filter and bias-corrected fuzzy C-means algorithm, allows for automated segmentation of data acquired through four-dimensional PCT. Using this integrated approach, the three-dimensional coarsening morphology of an Aluminum-29.9 wt% Silicon alloy can be analyzed.

Excessive daytime somnolence and increased rapid eye movement pressure in myotonic dystrophy.

STUDY OBJECTIVES: Sleep studies at Duke University Medical Center were retrospectively reviewed to investigate causes of excessive daytime sleepiness (EDS) in our myotonic dystrophy1 (DM1) patient population, identified by an abnormal CTG expansion on chromosome 19. Excessive daytime sleepiness, an accentuated desire for sleep or the occurrence of sleep episodes that interfere with normal wakefulness, is common in patients with DM1. Sleep abnormalities, such as central and obstructive sleep apnea, have been extensively reported; however, many DM1 patients suffer from EDS in the absence of any identified respiratory dysrhythmia. DESIGN: Nineteen DM1 patients, with the clinical diagnosis and genetic confirmation in the proband or a related family member, had a sleep evaluation. Polysomnogram (PSG) and mean sleep latency test (MSLT) results were retrospectively reviewed. SETTING: N/A. PARTICIPANTS: N/A. INTERVENTIONS: N/A. MEASUREMENTS AND RESULTS: Most DM1 patients demonstrated grade 3 (distal weakness) or grade 4 (mild to moderate proximal weakness) on the myotonic dystrophy impairment rating scale. All patents had a PSG, with 13 patients having an MSLT the following day. Clinically significant respiratory abnormalities on PSG, defined in this study as a respiratory disturbance index > 15 and/or upper airway resistance syndrome, could not explain the EDS observed in 14 of 19 patients. Decreased mean sleep latency was observed in 12 of 13 patients evaluated by MSLT, while sleep onset REM sleep was seen in 8 of 13 patients. Pathologic REM onset (2 or more SOREMs on MSLT) was seen in 5 of 13 patients, with 3 of those 5 patients having a PSG with RDI < or = 5. CONCLUSIONS: Most DM1 patients did not have significant respiratory abnormalities on PSG to explain the manifested EDS. Objective sleepiness is common in DM1, and pathologic REM pressure can be commonly observed. These observations imply an intrinsic hypersomnolence sometimes accompanied by abnormal REM pressure may be an integral part of EDS in DM1 patients.

Epilepsy associated with lupus anticoagulant.

INTRODUCTION: Lupus anticoagulant (LA) is commonly present in patients with systemic lupus erythematosus (SLE) who present with an ischemic cerebral stroke. Reports have noted the presence of LA in patients with epilepsy who do not have SLE. These patients are usually elderly, and it has been postulated that their epilepsy is due to subclinical ischemic infarcts. METHODS: Two cases are presented in young patients (age < 35 years) who developed epileptic seizures and were LA positive. These patients did not have SLE or have cerebral infarcts that could explain the presence of their seizures. RESULTS: A 28-year-old woman was admitted for aortic insufficiency and new onset seizures. The clinical history, physical examination and magnetic resonance imaging did not reveal an antecedent cortical ischemic event. Serological testing revealed the presence of LA. The second patient was a 33-year-old man with medically intractable epilepsy in whom serological testing revealed the presence of LA. The clinical history, physical examination, and MRI did not reveal any evidence of an antecedent ischemic event. Neither patient had SLE. CONCLUSIONS: In young patients without SLE and cerebral infarcts, LA may be associated with epileptic seizures.

Anticonvulsant actions of lamotrigine on spontaneous thalamocortical rhythms.

PURPOSE: This study examined the actions of lamotrigine (LTG) on epileptiform discharges resembling generalized absence (GA) and primary generalized tonic-clonic (GTC) seizures in rat thalamocortical (TC) brain slices and attempted to characterize further the cellular mechanisms of action of LTG on neuronal ionic conductances. METHODS: Rat TC slices generated spontaneous generalized epileptiform discharges after perfusion with a medium containing no added Mg(2+). Using multiple channel extracellular field-potential recordings in thalamus and cortex, the effects of LTG were characterized on two principal variants of activity that are similar to spike-wave discharges (SWDs) of GA epilepsy and GTC seizure discharges. These were termed simple TC burst complexes (sTBCs) and complex TC burst complexes (cTBCs), respectively. With whole-cell patch-clamp recording techniques in acutely dissociated TC neurons, the effects of LTG on GABA (gamma-aminobutyric acid)(A)-receptor-mediated currents and the low-threshold calcium current (I(T)) were examined. RESULTS: In field-potential recording studies in TC slices, both sTBCs and cTBCs were blocked by clinically relevant concentrations of LTG. In patch-clamp recording studies, LTG was found to be ineffective in the modulation of both GABA(A) receptors (GABARs) and I(T) in TC neurons. CONCLUSIONS: The efficacy of LTG on both variants of epileptiform discharges in TC slices clearly parallels its broad human clinical spectrum of action. This demonstrates that neurons within the TC system constitute one probable therapeutic target of LTG. However, LTG did not block either GABAR-mediated responses or I(T) in TC neurons. Modulation of these conductances represent likely cellular mechanisms of action of other antiepileptic drugs effective in the control of GA epilepsy. This suggests that LTG may have as yet uncharacterized effects that could combine with its previously defined sodium channel-blocking actions to explain its clinical utility in the control GA seizures.