MRI Features of Aquaporin-4 Antibody-Positive Longitudinally Extensive Transverse Myelitis: Insights into the Diagnosis of Neuromyelitis Optica Spectrum Disorders

BACKGROUND AND PURPOSE

Longitudinally extensive transverse myelitis is a well-documented spinal manifestation of neuromyelitis optica spectrum disorders, however, other forms of nontumorous myelopathy can also manifest as longitudinally extensive transverse myelitis. Our aim was to evaluate the MR imaging features of aquaporin-4 antibody-positive longitudinally extensive transverse myelitis, which is strongly associated with neuromyelitis optica spectrum disorders.

MATERIALS AND METHODS

We evaluated cervicomedullary junction involvement, cord expansion ratios, bright spotty lesions, the number of involved segments, skipped lesions, enhancement patterns, and axial distribution patterns using spinal MR imaging of 41 patients with longitudinally extensive transverse myelitis who underwent aquaporin-4 antibody testing. Univariate logistic regression analysis was performed to identify factors associated with aquaporin-4 antibody seropositivity, which were then used to develop a scoring system for diagnosing aquaporin-4 antibody-positive longitudinally extensive transverse myelitis. Interrater reliability for cord expansion ratio measurement and bright spotty lesions was determined using intraclass correlation coefficients and κ values, respectively.

RESULTS

Fifteen patients with longitudinally extensive transverse myelitis were aquaporin-4 antibody-positive. Sex (female), cervicomedullary junction involvement, a cord expansion ratio of >1.4, and bright spotty lesions were significantly associated with aquaporin-4 antibody seropositivity. The sensitivity and specificity of the scoring system were 73.3% and 96.2%, respectively. The interclass correlation value for the cord expansion ratio was 0.78, and the κ value for bright spotty lesions was 0.61.

CONCLUSIONS

Our scoring system, based on cervicomedullary junction involvement, higher cord expansion ratio, bright spotty lesions, and female sex, can facilitate the timely diagnosis of neuromyelitis optica spectrum disorders.

Outcome of alternative approach to displaced acetabular fractures

INTRODUCTION

Anatomical reduction of displaced acetabular fracture is not without its' limitations and complications. This study is conducted to assess clinical and radiological outcomes as well as complications of treating displaced acetabular fractures with emphasis on anatomical reduction in weight-bearing area, mainly the posterior column, and imperfect reduction of the anterior column is acceptable. However, stability of both columns is mandatory.

METHODS

It was a retrospective study carried out in a Level 1 arthroplasty and trauma centre. 23 patients (17 males, 6 females) with average age of 50.1 years (range, 36-68 years) with displaced acetabular fracture treated with combined incisions and plate-cable systems were included. There were 3 elementary and 18 associated fractures according to Letournel classification. Average follow-up was 23.5 months (range, 12-38.7 months). Mean operation time was 160min (range: 75-320min). Functional scores were evaluated using Harris Hip Score (HHS) whilst reduction was assessed by Matta criteria. Any displacement of reduction, osteoarthritis, heterotopic ossification, and other complications was recorded.

RESULT

65.2% (15/23) of the patients obtained excellent HHS and 21.7% (5/23) had good HHS. There were 12 anatomical, 6 imperfect, and 5 poor reductions. No displacement was recorded in final follow-up. Complications documented: three lateral femoral cutaneous nerve injuries, two conversions to total hip arthroplasty, three Brooker stage 1 heterotrophic ossification, one pulmonary embolism and one screw irritation. No incidence of wound breakdown, infection and radiological osteoarthritis was reported.

CONCLUSIONS

Imperfect reduction of the anterior column provided clinical outcomes that are as good as total anatomical reduction. This approach minimizes soft tissue damage and reduces perioperative morbidities.

Relaxation oscillator-realized artificial electronic neurons, their responses, and noise

A proof-of-concept relaxation oscillator-based leaky integrate-and-fire (ROLIF) neuron circuit is realized by using an amorphous chalcogenide-based threshold switch and non-ideal operational amplifier (op-amp). The proposed ROLIF neuron offers biologically plausible features such as analog-type encoding, signal amplification, unidirectional synaptic transmission, and Poisson noise. The synaptic transmission between pre- and postsynaptic neurons is achieved through a passive synapse (simple resistor). The synaptic resistor coupled to the non-ideal op-amp realizes excitatory postsynaptic potential (EPSP) evolution that evokes postsynaptic neuron spiking. In an attempt to generalize our proposed model, we theoretically examine ROLIF neuron circuits adopting different non-ideal op-amps having different gains and slew rates. The simulation results indicate the importance of gain in postsynaptic neuron spiking, irrespective of the slew rate (as long as the rate exceeds a particular value), providing the basis for the ROLIF neuron circuit design. Eventually, the behavior of a postsynaptic neuron in connection to multiple presynaptic neurons via synapses is highlighted in terms of EPSP evolution amid simultaneously incident asynchronous presynaptic spikes, which in fact reveals an important role of the random noise in spatial integration.

The effect of doping Sb on the electronic structure and the device characteristics of Ovonic Threshold Switches based on Ge-Se

The Ovonic Threshold Switch (OTS) based on an amorphous chalcogenide material has attracted much interest as a promising candidate for a high-performance thin-film switching device enabling 3D-stacking of memory devices. In this work, we studied on the electronic structure of amorphous Sb-doped Ge_0.6Se_0.4 (in atomic mole fraction) film and its characteristics as to OTS devices. From the optical absorption spectroscopy measurement, the band gap (E_g) was found to decrease with increasing Sb content. In addition, as Sb content increased, the activation energy (E_a) for electrical conduction was found to decrease down to about one third of E_g from a half. As to the device characteristics, we found that the threshold switching voltage (V_th) drastically decreased with the Sb content. These results, being accountable in terms of the changes in the bonding configuration of constituent atoms as well as in the electronic structure such as the energy gap and trap states, advance an effective method of compositional adjustment to modulate V_th of an OTS device for various applications.

Modeling of particle removal in the first coarse media of direct horizontal-flow roughing filtration

Horizontal-Flow Roughing Filtration (HRF) is an alternative pretreatment method e.g. prior to Slow Sand Filtration (SSF). However, some of its limitations are that the effluent quality drops drastically at higher turbidity (>200NTU) and at higher filtration rate (>1 m h(-1)). To overcome these drawbacks, we suggested Direct Horizontal-Flow Roughing Filtration (DHRF), which is a modified system of Horizontal-Flow Roughing Filtration (HRF) by addition of a low dose of coagulant prior to filtration. To optimize the DHRF configuration, a conceptual and mathematical model for the coarse compartment has been developed in analogy with multi-plate settler. Data from simple column settling test can be used in the model to predict the filter performance. Furthermore, the model developed herein has been validated by successive experiments. The conventional column settling test has been found to be handy and useful to predict the performance of DHRF for different raw water characteristics (e.g. coagulated or uncoagulated water, different amounts of organic matter, etc.) and different initial process conditions (e.g. coagulant dose, mixing time and intensity, etc.). An optimum filter design for the coarse compartment (grain size 20 mm) has been found to be of 3m h(-1) filtration rate with filter length of 4-4.5 m.

Examining the effect of length/width ratio on the hydro-dynamic behaviour in a DAF system using CFD and ADV techniques

Dissolved air flotation (DAF) is a solid-liquid separation system that uses fine bubbles rising from the bottom to remove particles in water. In this study, we investigated the effect of L/W(L; length, W; width) on the hydrodynamic behavior in a DAF system using CFD (computational fluid dynamics) and ADV (acoustic Doppler velocimetry) technique. The factual full-scale DAF system, L/W ratio of 1:1, was selected and various UW ratio conditions (2:1, 3:1,4:1 and 5:1) were simulated with CFD. For modelling, 2-phase (gas-liquid) flow equations for the conservation of mass, momentum and turbulence quantities were solved using a Eulerian-Eulerian approach based on the assumption that a very small particle is applied in the DAF system. Also, for verification of CFD simulation results, we measured the actual velocity at some points in the full-scale DAF system with the ADV technique. Both the simulation and the measurement results were in good accordance with each other. We concluded that the L/W ratio and outlet geometry play an important role for flow pattern and fine bubble distribution in the flotation zone. In the ratio of 1:1, the dead zone is less than those in other cases. On the other hand, in the ratio of 5:1, the fine bubbles were more evenly distributed.

A case study of dissolved air flotation for seasonal high turbidity water in Korea

A DAF (Dissolved-Air-Flotation) process has been designed considering raw water quality characteristics in Korea. Although direct filtration is usually operated, DAF is operated when freshwater algae blooms occur or raw water turbidity becomes high. Pre-sedimentation is operated in case when the raw water turbidity is very high due to rainstorms. A main feature of this plant is that the operation mode can be changed (controlled) based on the characteristics of the raw water to optimize the effluent quality and the operation costs. Treatment capacity (surface loading rate) and efficiency of DAF was found to be better than the conventional sedimentation process. Moreover, low-density particles (algae and alum flocs) are easily separated while the removal of them by sedimentation is more difficult. One of the main concerns for DAF operation is a high raw water turbidity. DAF is not adequate for raw water, which is more turbid than 100 NTU. In order to avoid this problem, pre-sedimentation basins are installed in the DAF plant to decrease the turbidity of the DAF inflow. For simulation of the actual operation, bench and full-scale tests were performed for highly turbid water conditions. Consequently, it is suggested that pre-sedimentation with optimum coagulation prior to DAF is the appropriate treatment scheme.

Pharmacokinetics of theophylline and caffeine after intravenous administration of aminophylline to premature neonates in Korea

Theophylline has been widely used to treat apnea of premature neonates. The purpose of this study was to compare the pharmacokinetic parameters of theophylline and caffeine after intravenous administration of aminophylline to seven Korean low-birthweight neonates with apnea to those in other countries. The serum concentrations of theophylline and caffeine were measured simultaneously by high-performance liquid-chromatography (HPLC). The mean (+/- S.E.M.) birth weight and gestational period were 1190 +/- 253 g and 31.5 +/- 1.99 weeks, respectively. The mean (+/- S.E.M.) theophylline maintenance dosage was 1.28 +/- 0.15 mg/kg (given as equivalent aminophylline solution) every six hours. The mean (+/- S.E.M.) volume of distribution, 0.937 +/- 0.232 l/kg, elimination rate constant, 0.0249 +/- 0.0095/h, elimination half-life, 32.1 +/- 12.1 h, and total body clearance, 21.7 +/- 6.18 ml/h/kg, of theophylline in Korean premature neonates were comparable to the values of neonates in other countries. For caffeine, the mean (+/- S.E.M.) elimination half-life was 95.1 +/- 25.4 h and the elimination rate constant was 0.0079 +/- 0.0024/h. The mean (+/- S.E.M.) serum concentrations of theophylline and caffeine on the sixth day after aminophylline infusion were 10.4 +/- 2.28 microg/ml (range, 6.38-13.4 microg/ml) and 2.94 +/- 0.98 microg/ml (range, 1.80-4.44 microg/ml), respectively. The mean (+/- S.E.M.) caffeine to theophylline concentration ratio on the day after discontinuation of aminophylline infusion was 0.71 +/- 0.23 (range, 0.39-1.03).

Interactive effects of fluoride and aluminum uptake and accumulation in bones of rabbits administered both agents in their drinking water

Fluoride (F) and aluminum (Al), which are known to form a strong complex, are both present in finished drinking water. The effect of F and AI on one another's tissue accumulation was determined using adult male New Zealand white rabbits. Thirty-six rabbits (three per group) were given Purina Rabbit Chow and drinking water containing no F or AI, F alone (1, 4, or 50 ppm F as NaF), Al alone, (100 or 500 ppm Al as AlCl3), or a combination of F and Al, ad libitum for 10 wk. None of these treatments altered food intake or weight gain in these rabbits. However, rabbits treated with 1 ppm F and 500 ppm Al consumed significantly less water than control rabbits. The F accumulation in plasma, urine, incisors, and tibia was increased as the F addition to the drinking water increased within groups receiving a single concentration of Al. In contrast, F accumulation in plasma, urine, incisors, and tibia decreased as the Al concentration increased within groups receiving a single F concentration, indicative of decreased intestinal absorption. Importantly, Al levels in tibia were significantly increased by the addition of F to the drinking water, even in animals receiving no Al in their drinking water. The effect of F on Al accumulation in bone was confirmed by our evaluating Al levels in sterna harvested from rats treated with 0 or 79 ppm F (as NaF in the drinking water) in a study conducted by the National Toxicology Program (Bucher et al., 1991). Therefore, some of the osteotoxicity seemingly associated with high F levels in bone may be due to the accumulation of Al or an Al-F complex.

Effect of aluminum on fluoride uptake by Salmonella typhimurium TA98; implications for the Ames mutagenicity assay

The bacterium Salmonella typhimurium TA98 (TA98) is commonly used in the Ames test to detect frameshift mutations. Published Ames test results for fluoride mutagenicity are inconsistent. We considered that this might be due to an unnoticed variable in experimental conditions. Al and F, both present in finished drinking water, form a stable complex. The effect of Al and F uptake by TA98 cells was evaluated and any effect of Al on Ames test results for F was also determined. A known number of TA98 cells in 0.1 M potassium phosphate buffer (PPB, pH 7.4) was incubated with buffer only, and various concentrations of Al as AlCl3, F as NaF, or aluminum and fluoride (Al: F, 1: 62.5 w/w) for 1 h at 37 degrees C in a shaking incubator. Neither F (19 and 190 ppm), Al (0.3 and 3 ppm), nor Al:F (7.6 ppb-3 ppm: 0.45-190 ppm) was found to be mutagenic as assessed by a modification of the Ames standard plate incorporation assay. Intracellular Al accumulated in a concentration-dependent manner from 0.5 to 4.5 ppm, then decreased as Al was increased to 9.5 ppm. Intracellular F was below the limit of detection (0.2 ppm) even when the medium contained 589 ppm F. However, F was taken up from media containing greater than 200 ppm F, providing that aluminum was also present. Experiments carried out using N-2-hydroxyethyl-piperazine-N'-2-ethanesulfonic acid (HEPES) buffer (100 mM, pH 7.4) gave similar results for F uptake, suggesting the Al requirement for F uptake is not an artifact caused by buffer chelation. However, Al uptake was not biphasic from HEPES buffer, but increased with dose over the range studied (1.5-9.0 ppm). While F did not appear to cause mutations in the presence or absence of Al, it was concluded that the mutagenicity test, using TA98, is not suitable for the evaluation of F mutagenicity.