Approaches to characterizing oscillatory burst detection algorithms for electrophysiological recordings

BACKGROUND

Cognitive processes are associated with fast oscillations of the local field potential and electroencephalogram. There is a growing interest in targeting them because these are disrupted by aging and disease. This has proven challenging because they often occur as short-lasting bursts. Moreover, they are obscured by broad-band aperiodic activity reflecting other neural processes. These attributes have made it exceedingly difficult to develop analytical tools for estimating the reliability of detection methods.

NEW METHOD

To address this challenge, we developed an open-source toolkit with four processing steps, that can be tailored to specific brain states and individuals. First, the power spectrum is decomposed into periodic and aperiodic components, each of whose properties are estimated. Second, the properties of the transient oscillatory bursts that contribute to the periodic component are derived and optimized to account for contamination from the aperiodic component. Third, using the burst properties and aperiodic power spectrum, surrogate neural signals are synthesized that match the observed signal's spectrotemporal properties. Lastly, oscillatory burst detection algorithms run on the surrogate signals are subjected to a receiver operating characteristic analysis, providing insight into their performance.

RESULTS

The characterization algorithm extracted features of oscillatory bursts across multiple frequency bands and brain regions, allowing for recording-specific evaluation of detection performance. For our dataset, the optimal detection threshold for gamma bursts was found to be lower than the one commonly used.

COMPARISON WITH EXISTING METHODS

Existing methods characterize the power spectrum, while ours evaluates the detection of oscillatory bursts.

CONCLUSIONS

This pipeline facilitates the evaluation of thresholds for detection algorithms from individual recordings.

Robust Ellipse Fitting Based on Maximum Correntropy Criterion With Variable Center

The presence of radically irregular data points (RIDPs), which are referred to as the subset of measurements that represents no or little information, can significantly degrade the performance of ellipse fitting methods. We develop an ellipse fitting method that is robust to RIDPs based on the maximum correntropy criterion with variable center (MCC-VC), where an adaptable Laplacian kernel is used. For single ellipse fitting, we formulate a non-convex optimization problem and divide it into two subproblems, one to estimate the kernel bandwidth and the other the kernel center. We design sufficiently accurate convex approximation to each subproblem that will lead to computationally efficient closed-form solutions. The two subproblems are solved in an alternate manner until convergence is reached. We also investigate coupled ellipses fitting. While there exist multiple ellipses fitting methods in the literature, we develop a coupled ellipses fitting method by exploiting the underlying special structure, where the associations between the data points and ellipses are absent in the problem. The proposed method first introduces an association vector for each data point and then formulates a non-convex mixed-integer optimization problem to establish the data associations, which is approximately solved by relaxing it into a second-order cone program. Using the estimated data associations, we then extend the proposed single ellipse fitting method to accomplish the final coupled ellipses fitting. The proposed method is shown to perform significantly better than the existing methods using both simulated data and real images.

Abstract WMP97: Symptomatic Steno-occlusion Of Major Cerebral Arteries And Stroke Recurrence In Acute Ischemic Stroke Patients With Atrial Fibrillation

Introduction: There is lack of knowledge on whether symptomatic steno-occlusion (SYSO), common in acute ischemic stroke (AIS) patients with atrial fibrillation (AF), could increase the long-term risk of stroke recurrence in these patients.

Methods: From a prospective cohort of patients with AIS and AF enrolled in 14 centers between Oct 2017 and Dec 2018, we identified patients who underwent MR angiography during hospitalization and completed 3-year follow-up including death during follow-up. SYSO was defined as (1) ≥ 50% stenosis or occlusion of cerebral arteries relevant to acute infarction or (2) any residual stenosis after endovascular treatment. Using cause-specific hazard models with non-stroke death as a competing risk, the risk of any recurrent stroke and recurrent ischemic stroke was estimated according to SYSO, respectively.

Results: A total of 889 patients (mean age, 74.4 years; men, 54.6 %; median NIHSS, 6) were analyzed for this study. During the median 1096 days of follow-up, 152 any recurrent strokes, 142 recurrent ischemic strokes, and 208 deaths were observed. Patients with SYSO, compared to those without, were more likely to be older, be female, have hypertension, diabetes and history of stroke/TIA, and be on antiplatelets at discharge and were less likely to be on anticoagulants at discharge ( p <.05). The cumulative incidence of recurrent stroke in patients with and without SYSO was 25.2% and 8.3% at 1 month, 33.1% and 9.9% at 1 year, and 41.8% and 13.1% at 3 years, respectively ( p <.001). With adjusting age, sex, hypertension, diabetes, history of stroke/TIA, discharge antiplatelets, and discharge anticoagulants, SYSO increased the risk of any stroke recurrence (adjusted hazard ratio [95% confidence interval]; 3.02 [2.18-4.20]; p <.001) and ischemic stroke recurrence (3.20 [2.28-4.51]; p <.001).

Conclusions: SYSO in AIS patients with AF substantially increased the risk of recurrent stroke by a 3-fold or more. Accordingly, SYSO should be considered in stratifying the risk of recurrence in AIS patients with AF.

Abstract 44: Impact Of Novel Oral Anticoagulant Use On Secular Trend Of Vascular Events Or Death After Atrial Fibrillation-related Acute Ischemic Stroke

Introduction: Now novel oral anticoagulants (NOAC) are strongly recommended for secondary stroke prevention in patients with atrial fibrillation (AF). However, it remains unclear to what extent the introduction of NOACs improved clinical outcomes in real-world practice.

Methods: Using a nationwide prospective multi-center stroke registry database, we identified consecutive AIS patients with AF enrolled between Jan 2011 and Dec 2019, and analyzed one-year clinical events and NOAC prescription at discharge. The primary outcome was the composite of stroke, myocardial infarction, and all-cause death. To assess the mediation effect of NOAC on the outcomes, we performed natural effect models according to the calendar year. The exposure-mediator analysis, exposure-outcome analysis, and mediator-outcome analysis were performed using multivariate regression analysis according to the characteristics of the variables.

Results: We analyzed 12,500 patients (mean age, 74.4 years; 51.3% male; median NIHSS at presentation, 8). From 2011 to 2019, the cumulative one-year incidence of the primary composite outcome (28.3% to 22.1%), all-cause mortality (23.8% to 17.9%), and stroke recurrence (8.3% to 5.1%) significantly decreased, while the NOAC prescription rate at discharge increased (0% to 75.6%). One-year increase in the calendar year was independently associated with a delayed occurrence of primary composite outcomes (Step 1: adjusted Time Ratio (aTR), 1.10; 95% confidence interval, 1.07-1.14) and with an increased NOAC prescription rate (Step 2: adjusted odds ratio, 2.20; 2.14-2.27). Increase in the NOAC prescription rate was significantly associated with the delayed occurrence of primary composite outcome (Step 3: aTR, 3.80; 3.15-4.58). However, after controlling for the NOAC prescription rate (mediator), the calendar year was no longer associated with the primary composite outcomes. (Step 4: aTR, 0.78; 95% CI 0.60-1.03). Thus, our results indicate full mediation of NOAC prescription in the association between the calendar year and primary composite outcomes.

Conclusion: The reduced risk of major vascular events or death over time in AIS patients with AF was fully mediated by the increase in NOAC use.

Non-Invasive Heart Rate Estimation From Ballistocardiograms Using Bidirectional LSTM Regression

Non-invasive heart rate estimation is of great importance in daily monitoring of cardiovascular diseases. In this paper, a bidirectional long short term memory (bi-LSTM) regression network is developed for non-invasive heart rate estimation from the ballistocardiograms (BCG) signals. The proposed deep regression model provides an effective solution to the existing challenges in BCG heart rate estimation, such as the mismatch between the BCG signals and ground-truth reference, multi-sensor fusion and effective time series feature learning. Allowing label uncertainty in the estimation can reduce the manual cost of data annotation while further improving the heart rate estimation performance. Compared with the state-of-the-art BCG heart rate estimation methods, the strong fitting and generalization ability of the proposed deep regression model maintains better robustness to noise (e.g., sensor noise) and perturbations (e.g., body movements) in the BCG signals and provides a more reliable solution for long term heart rate monitoring.

Robust Ellipse Fitting With Laplacian Kernel Based Maximum Correntropy Criterion

The performance of ellipse fitting may significantly degrade in the presence of outliers, which can be caused by occlusion of the object, mirror reflection or other objects in the process of edge detection. In this paper, we propose an ellipse fitting method that is robust against the outliers, and thus maintaining stable performance when outliers can be present. We formulate an optimization problem for ellipse fitting based on the maximum entropy criterion (MCC), having the Laplacian as the kernel function from the well-known fact that the l₁ -norm error measure is robust to outliers. The optimization problem is highly nonlinear and non-convex, and thus is very difficult to solve. To handle this difficulty, we divide it into two subproblems and solve the two subproblems in an alternate manner through iterations. The first subproblem has a closed-form solution and the second one is cast as a convex second-order cone program (SOCP) that can reach the global solution. By so doing, the alternate iterations always converge to an optimal solution, although it can be local instead of global. Furthermore, we propose a procedure to identify failed fitting of the algorithm caused by local convergence to a wrong solution, and thus, it reduces the probability of fitting failure by restarting the algorithm at a different initialization. The proposed robust ellipse fitting method is next extended to the coupled ellipses fitting problem. Both simulated and real data verify the superior performance of the proposed ellipse fitting method over the existing methods.

Life cycle assessment (LCA) of electrically-enhanced POME filtration: Environmental impacts of conductive-membrane formulation and process operating parameters

This study assessed the environmental impacts of the formulation of graphene oxide (GO)/multi-walled carbon nanotubes (MWCNTs) conductive membranes and of the process operating parameters of electrically-enhanced palm oil mill effluent (POME) filtration. Two different analyses approaches were employed, cradle-to-gate approach for conductive membrane production and gate-to-gate approach for the POME filtration process. The parameters in conductive-membrane formulation (e.g. the weight ratio of carbon nanomaterials, and concentration of GO/MWCNT nanohybrids) and process operating parameters (e.g. electric field strength and electricity operating mode) were investigated. The findings herein are twofold. Firstly, for the fabrication of GO/MWCNT conductive membranes, the best weight ratio of GO:MWCNTs was found to be 1:9, given its superior membrane electrical conductivity with lower environmental impacts by 8.51% compared to pristine MWCNTs. The most suitable concentration of carbon nanomaterials was found to be 5 wt%, given its lowest impacts on resource depletion, human health, and ecosystems. Secondly, for the electrically-enhanced POME filtration, the optimum process operating parameters were found to be the application of an electric field of 300 V/cm in the continuous mode, given its lower environmental impacts (22.99%-89.30%) secondary to its requirement of the least electricity to produce permeate. The present study has established not only the optimized conditions in membrane formulation but also the operating parameters of electrically-enhanced filtration; such findings enable the use of cleaner production and sustainable approach to minimize fouling for industrial applications, whilst maintaining excellent efficiency.

Monitoring the Relative Blood Pressure Using a Hydraulic Bed Sensor System

We propose a nonwearable hydraulic bed sensor system that is placed underneath the mattress to estimate the relative systolic blood pressure of a subject, which only differs from the actual blood pressure by a scaling and an offset factor. Two types of features are proposed to obtain the relative blood pressure, one based on the strength and the other on the morphology of the bed sensor ballistocardiogram pulses. The relative blood pressure is related to the actual by a scale and an offset factor that can be obtained through calibration. The proposed system is able to extract the relative blood pressure more accurately with a less sophisticated sensor system compared to those from the literature. We tested the system using a dataset collected from 48 subjects right after active exercises. Comparison with the ground truth obtained from the blood pressure cuff validates the promising performance of the proposed system, where the mean correlation between the estimate and the ground truth is near to 90% for the strength feature and 83% for the morphology feature.

Multiple Instance Dictionary Learning for Beat-to-Beat Heart Rate Monitoring From Ballistocardiograms

A multiple instance dictionary learning approach, dictionary learning using functions of multiple instances (DL-FUMI), is used to perform beat-to-beat heart rate estimation and to characterize heartbeat signatures from ballistocardiogram (BCG) signals collected with a hydraulic bed sensor. DL-FUMI estimates a "heartbeat concept" that represents an individual's personal ballistocardiogram heartbeat pattern. DL-FUMI formulates heartbeat detection and heartbeat characterization as a multiple instance learning problem to address the uncertainty inherent in aligning BCG signals with ground truth during training. Experimental results show that the estimated heartbeat concept obtained by DL-FUMI is an effective heartbeat prototype and achieves superior performance over comparison algorithms.

Testing non-wearable fall detection methods in the homes of older adults

In this paper, we describe two longitudinal studies in which fall detection sensor technology was tested in the homes of older adults. The first study tested Doppler radar, a two-webcam system, and a depth camera system in ten apartments for two years. This continuous data collection allowed us to investigate the real-world setting of target users and compare the advantages and limitations of each sensor modality. Based on this study, the depth camera was chosen for a current ongoing study in which depth camera systems have been installed in 94 additional older adult apartments. We include a discussion of the different sensor systems, the pros and cons of each, and results of the fall detection and false alarms in the older adult homes.

Enhancement of Chlorella vulgaris harvesting via the electro-coagulation-flotation (ECF) method

This article explores the potential of using an electro-coagulation-flotation (ECF) harvester to allow flotation of microalgae cells for surface harvesting. A response surface methodology (RSM) model was used to optimize ECF harvesting by adjusting electrode plate material, electrode plate number, charge of the electrodes, electrolyte concentration, and pH value of the culture solution. The result revealed that three aluminum electrode plates (one anode and two cathodes), brine solution (8 g/L), and acidity (pH = 4) of culture solution (optimized ECF harvester) The highest flocculant concentration was measured at 2966 mg/L after 60 min and showed a 79.8 % increase of flocculation concentration. Such results can provide a basis for designing a large-scale microalgae harvester for commercial use in the future.

Maximization of cell growth and lipid production of freshwater microalga Chlorella vulgaris by enrichment technique for biodiesel production

Chlorella vulgaris was cultivated under limitation and starvation and under controlled conditions using different concentrations of nitrate (NaNO₃) and phosphate (K₂HPO₄ and KH₂PO₄) chemicals in modified Bold basal medium (BBM). The biomass and lipid production responses to different media were examined in terms of optical density, cell density, dry biomass, and lipid productivity. In the 12-day batch culture period, the highest biomass productivity obtained was 72.083 mg L^-1 day^-1 under BBM - N_controlP_limited condition. The highest lipid content, lipid concentration, and lipid productivity obtained were 53.202 %, 287.291 mg/L, and 23.449 mg L^-1 day^-1 under BBM - N_ControlP_Deprivation condition, respectively. Nitrogen had a major effect in the biomass concentration of C. vulgaris, while no significant effect was found for phosphorus. Nitrogen and phosphorus starvation was found to be the strategy affecting the lipid accumulation and affected the lipid composition of C. vulgaris cultures.

Robust heartbeat detection from in-home ballistocardiogram signals of older adults using a bed sensor

We propose a simple and robust method to detect heartbeats using the ballistocardiogram (BCG) signal that is produced by a hydraulic bed sensor placed under the mattress. The proposed method is found beneficial especially when the BCG signal does not display consistent J-peaks, which can often be the case for overnight, in-home monitoring, especially with frail seniors. Heartbeat detection is based on the short-time energy of the BCG signal. Compared with previous methods that rely on the J-peaks observed from the BCG amplitude, we are able to achieve considerable improvement even when significant distortions are present. Test results are included for different BCG waveform patterns from older adults.

Cultivation of Chlorella vulgaris in Column Photobioreactor for Biomass Production and Lipid Accumulation

Microalgae have been used as energy resources in recent decades to mitigate the global energy crisis. As the demand for pure microalgae strains for commercial use increases, designing an effective photobioreactor (PBR) for mass cultivation is important. Chlorella vulgaris, a local freshwater microalga, was used to study the algal biomass cultivation and lipid production using various PBR configurations (bubbling, air-lift, porous air-lift). The results show that a bubbling column design is a better choice for the cultivation of Chlorella vulgaris than an air-lift one. The highest biomass concentration in the bubbling PBR was 0.78 g/L while the air-lift PBR had a value of 0.09 g/L. Key operating parameters, including draft-tube length and bubbling flowrate, were then optimized based on biomass production and lipid yield. The highest lipid content was in the porous air-lift PBR and the air-lift PBR with shorter draft tube (35 cm) was also better than a longer one (50 cm) for algal cultivation, but the microalgae attachment on the inner tube of PBR always occurred. The highest biomass concentration could be produced under the highest gas flowrate of 2.7 L/min, whereas the lowest dry cell mass was under the lowest gas flowrate of 0.2 L/min.

Scenedesmus quadricauda for Nutrient Removal and Lipid Production in Wastewater

Scenedesmus quadricauda, a local freshwater microalga, was used to treat primary settled and filtrate wastewater and to produce algal lipid. For the primary settled wastewater, the maximum biomass concentrations of acclimated and unacclimated microalgae were 0.995 g/L and 0.940 g/L, respectively. Over 90% orthophosphate and 95% ammonia nitrogen in the acclimated and unacclimated cultures, respectively, were removed after five days. The lipid contents of the microalgae were higher than 13% in all cultures. The highest growth rate occurred in the 25% filtrate culture. Over 80% phosphate was removed under the 25% and 50% filtrate cultures within six days, while over 90% ammonia nitrogen was removed within five days under both conditions. The lipid content was the highest (18.1%) under the 50% filtrate condition. C16:0, C18:2n6, and C18:3n3 were dominant fatty acids. In conclusion, S. quadricauda is a viable candidate for wastewater treatment and lipid production.

A theoretical study on the placement of microphone arrays for improving the localization accuracy of a fall

Falling is a common health problem for elderly. To address the problem, we are currently developing an acoustic fall detection system, FADE, which automatically detects a fall and reports to the caregiver. Of great importance of the fall detection system is a low false alarm rate that can be achieved by knowing where the acoustic signal comes from. The previous work showed the sound source localization can be determined by using an 8-microphone circular array, but the accuracy varies when placing the array at different positions. To further improve the localization accuracy, a second array can be added. In this paper we investigate the variations of localization accuracy of a fall signal when one or two arrays are placed at different positions in a room. The accuracy is evaluated by the Cramér-Rao Lower Bound (CRLB). The CRLB aids the determination of the best theoretical placement of one or two arrays in a room for locating the sound source.

Doppler radar fall activity detection using the wavelet transform

We propose in this paper the use of Wavelet transform (WT) to detect human falls using a ceiling mounted Doppler range control radar. The radar senses any motions from falls as well as nonfalls due to the Doppler effect. The WT is very effective in distinguishing the falls from other activities, making it a promising technique for radar fall detection in nonobtrusive inhome elder care applications. The proposed radar fall detector consists of two stages. The prescreen stage uses the coefficients of wavelet decomposition at a given scale to identify the time locations in which fall activities may have occurred. The classification stage extracts the time-frequency content from the wavelet coefficients at many scales to form a feature vector for fall versus nonfall classification. The selection of different wavelet functions is examined to achieve better performance. Experimental results using the data from the laboratory and real inhome environments validate the promising and robust performance of the proposed detector.

Assessment of heavy metals/metalloid (As, Pb, Cd, Ni, Zn, Cr, Cu, Mn) concentrations in edible fish species tissue in the Pearl River Delta (PRD), China

The major aim of this study was to investigate heavy metal content of edible fish in the PRD. Eleven species of fish (consisting of 711 individuals) [catfish (Clarias fuscus), tilapia (Oreochromis mossambicus), grass carp (Ctenopharyngodon idellus), bighead carp (Aristichthys nobilis), mandarin fish (Siniperca kneri), snakehead (Channa asiatiea), black bass (Micropterus salmoides), mangrove snapper (Lutjanus griseus), star snapper (Lutjanu stellatus), snubnose pompano (Trachinotus blochii) and orange-spotted grouper (Epinephelus coioides)] were collected for the analyses of heavy metals. Overall concentrations (mg/kg, ww) in the fish muscles were: As (0.03-1.53), Pb (0.03-8.62), Cd (0.02-0.06), Ni (0.44-9.75), Zn (15.7-29.5), Cr (0.22-0.65), Cu (0.79-2.26), Mn (0.82-6.91). Significant level of Pb were found in tilapia at all locations. It is recommended that heavy metal concentrations in different fish species must be determined on a regular basis in the future so as to reduce human health risks from acute and chronic food intoxication.

Efficient source separation algorithms for acoustic fall detection using a microsoft kinect

Falls have become a common health problem among older adults. In previous study, we proposed an acoustic fall detection system (acoustic FADE) that employed a microphone array and beamforming to provide automatic fall detection. However, the previous acoustic FADE had difficulties in detecting the fall signal in environments where interference comes from the fall direction, the number of interferences exceeds FADE's ability to handle or a fall is occluded. To address these issues, in this paper, we propose two blind source separation (BSS) methods for extracting the fall signal out of the interferences to improve the fall classification task. We first propose the single-channel BSS by using nonnegative matrix factorization (NMF) to automatically decompose the mixture into a linear combination of several basis components. Based on the distinct patterns of the bases of falls, we identify them efficiently and then construct the interference free fall signal. Next, we extend the single-channel BSS to the multichannel case through a joint NMF over all channels followed by a delay-and-sum beamformer for additional ambient noise reduction. In our experiments, we used the Microsoft Kinect to collect the acoustic data in real-home environments. The results show that in environments with high interference and background noise levels, the fall detection performance is significantly improved using the proposed BSS approaches.

Pulse rate estimation using hydraulic bed sensor

We propose in this paper an effective method to obtain the pulse rate from a hydraulic sensor that is placed under the mattress. The sensor captures the superposition of the ballistocardiogram (BCG) and the respiration signals. The BCG is modeled as the j-peak with a frequency modulation component. The proposed method utilizes the Hilbert transform to effectively capture the j-peak, which allows the pulse rate information to come out distinctively in the frequency domain. Among the five subjects tested, the error in pulse rate estimation is less than 1%.

Doppler radar sensor positioning in a fall detection system

Falling is a common health problem for more than a third of the United States population over 65. We are currently developing a Doppler radar based fall detection system that already has showed promising results. In this paper, we study the sensor positioning in the environment with respect to the subject. We investigate three sensor positions, floor, wall and ceiling of the room, in two experimental configurations. Within each system configuration, subjects performed falls towards or across the radar sensors. We collected 90 falls and 341 non falls for the first configuration and 126 falls and 817 non falls for the second one. Radar signature classification was performed using a SVM classifier. Fall detection performance was evaluated using the area under the ROC curves (AUCs) for each sensor deployment. We found that a fall is more likely to be detected if the subject is falling toward or away from the sensor and a ceiling Doppler radar is more reliable for fall detection than a wall mounted one.

Improving automatic sound-based fall detection using iVAT clustering and GA-based feature selection

Falls represent an important health problem for older adults. This issue continues to generate interest in the research and development of fall detection systems. In previous work we proposed an acoustic fall detection system (acoustic-FADE) that employs an 8-microphone circular array to automatically detect falls. Acoustic-FADE has achieved encouraging results: 100% detection at 3% false alarm rate in laboratory tests. In this paper, we use a dataset from previous work to investigate how to further improve AFADE performance. To analyze the relationship between fall and non-fall signatures we used the improved visual assessment of tendency (iVAT) clustering algorithm in conjunction with a nearest neighbor based distance to find the most challenging false alarms. Then, we employed a genetic algorithm (GA) framework to perform feature selection and find the mel-frequency cepstral coefficients (MFCC) that improve the classification performance. We found that using only three MFCC coefficients (1, 28, 29) instead of our previous choice (1,2,3,4,5,6) improves the classification performance.

A microphone array system for automatic fall detection

More than a third of elderly fall each year in the United States. It has been shown that the longer the lie on the floor, the poorer is the outcome of the medical intervention. To reduce delay of the medical intervention, we have developed an acoustic fall detection system (acoustic-FADE) that automatically detects a fall and reports it promptly to the caregiver. Acoustic-FADE consists of a circular microphone array that captures the sounds in a room. When a sound is detected, acoustic-FADE locates the source, enhances the signal, and classifies it as "fall" or "nonfall." The sound source is located using the steered response power with phase transform technique, which has been shown to be robust under noisy environments and resilient to reverberation effects. Signal enhancement is performed by the beamforming technique based on the estimated sound source location. Height information is used to increase the specificity. The mel-frequency cepstral coefficient features computed from the enhanced signal are utilized in the classification process. We have evaluated the performance of acoustic-FADE using simulated fall and nonfall sounds performed by three stunt actors trained to behave like elderly under different environmental conditions. Using a dataset consisting of 120 falls and 120 nonfalls, the acoustic-FADE achieves 100% sensitivity at a specificity of 97%.

Improving acoustic fall recognition by adaptive signal windowing

Each year more than a third of elderly fall in the United States. To address this problem we are developing an acoustic fall detection system based on a microphone array. The main task of the acoustic system is to detect all the falls that occur in an indoor environment while producing as few as possible false alarms. One of the challenges of this task is to accurately locate where the fall signal comes from so that beamforming can be applied to improve the recognition of fall signals. In this paper we describe a simple fall signal location procedure that proved effective in preliminary testing.

Acoustic fall detection using a circular microphone array

Falling is a common health problem for elderly. It is reported that more than one third of adults 65 and older fall each year in the United States. To address the problem, we are currently developing an acoustic fall detection system, FADE, which automatically detects a fall and reports it to the caregiver. In a previous version, FADE used a 3-microphone linear array to eliminate the false alarms produced by sounds produced well above the floor level. To improve the fall detection in noisy and reverberant environments, we replaced the linear array by an 8-microphone circular array that can provide a better 3-D estimation of the sound location. Preliminary experiments show that the sound location estimation performed by the circular array is reliable and robust to interference. We obtained encouraging classification results on a pilot dataset with 55 falls and 120 non-fall sounds.

Potential clinical role of 18F FDG-PET/CT in detecting hip prosthesis infection: a study in patients undergoing two-stage revision arthroplasty with an interim spacer

AIM

We evaluated the potential role of [18F]fluorodeoxyglucose-positron emission tomography/computed tomography ([18F]FDG-PET/CT) to identify latent infections at the site of an interim hip spacer after resection arthroplasty for hip prosthesis infection.

METHODS

Twelve patients with an interim hip spacer following resection arthroplasty (Group A) were investigated. Twelve patients with painful primary hip prostheses served as controls (Group B). All underwent PET/CT before surgery. Both non-attenuation-corrected (NAC) and attenuation-corrected (AC) images were analyzed. Serum C-reactive protein (CRP) levels were measured in 22 patients. Elevated CRP level was defined as >/=10 mg/L. The diagnosis of infection was based on the results of intraoperative tissue cultures, intraoperative pathology, and clinical follow-up.

RESULTS

FDG-PET/CT had 100% sensitivity and 100% negative predictive value for detection of latent infection in both groups. However, there were 4 and 3 false positive cases in Group A and Group B, respectively. Specificity improved from 50% to 62.5% in Group A, and from 62.5% to 87.5% in Group B when using NAC instead of AC. Seventeen patients had CRP values >/=10 mg/L, but only 8 were true positive for infection. FDG-PET/CT ruled out infection in 77.8% (7/9) of false-positive cases identified by CRP levels.

CONCLUSION

FDG-PET/CT is highly sensitive to detect latent infections in prosthetic hips and in interim hip spacers. The high negative predictive value of PET/CT scans is useful to rule out infections in patients with persistently elevated CRP levels. PET/CT might serve as an auxiliary tool to exclude latent infections in patients posing a clinical diagnostic dilemma.

A formal selection and pruning algorithm for feedforward artificial neural network optimization

A formal selection and pruning technique based on the concept of local relative sensitivity index is proposed for feedforward artificial neural networks. The mechanism of backpropagation training algorithm is revisited and the theoretical foundation of the improved selection and pruning technique is presented. This technique is based on parallel pruning of weights which are relatively redundant in a subgroup of a feedforward neural network. Comparative studies with a similar technique proposed in the literature show that the improved technique provides better pruning results in terms of reduction of model residues, improvement of generalization capability and reduction of network complexity. The effectiveness of the improved technique is demonstrated in developing neural network (NN) models of a number of nonlinear systems including three bit parity problem, Van der Pol equation, a chemical processes and two nonlinear discrete-time systems using the backpropagation training algorithm with adaptive learning rate.

Prognostic factors and adjuvant therapy in uterine carcinosarcoma

PURPOSE OF INVESTIGATION

The objective of this retrospective study was to investigate prognostic variables and impact of adjuvant therapy in uterine carcinosarcoma.

METHODS

The clinical information and pathological confirmation were reviewed for cases with uterine carcinosarcoma from 1984 to 2005. A total of 45 patients were eligible for analysis.

RESULTS

The median follow-up for survivors was 84 months. Five-year overall survival and progression-free survival (PFS) rates were 36.5% and 33.8%, respectively for Stage I-IV. Distant site metastasis with/without pelvic failure occurred in 83.3% of those with recurrence/progression. By multivariate analysis, older age (p = 0.001) and more than half of myometrial invasion (p = 0.002) were significant predictors of death, while only myometrial invasion (p = 0.022) was significantly associated with PFS. Stratified analyses demonstrated a monotonic trend of chemotherapy or chemoradiation to decrease death.

CONCLUSIONS

Our results suggested that age and depth of myometrial invasion were significant prognostic factors, and chemotherapy or chemoradiation seemed to be beneficial for uterine carcinosarcoma.

Spatial correlation coefficient images for ultrasonic detection

In ultrasonics, image formation and detection are generally based on signal amplitude. In this paper, we introduce correlation coefficient images as a signal-amplitude independent approach for image formation. The correlation coefficients are calculated between A-scans digitized at adjacent measurement positions. In these images, defects are revealed as regions of high or low correlation relative to the background correlations associated with noise. Correlation coefficient and C-scan images are shown to demonstrate flat-bottom-hole detection in a stainless steel annular ring and crack detection in an aluminum aircraft structure.

Supraclavicular lymph node metastases in cervical cancer

PURPOSE OF INVESTIGATION

To evaluate the outcome and prognostic factors of patients with supraclavicular lymph node (SCLN) involvement at primary diagnosis.

METHODS

We reviewed the medical records of cervical cancer patients primarily treated at Chang Gung Memorial Hospital between 1987 and 2005. Thirty-three patients with histologically confirmed SCLN metastasis at primary diagnosis were eligible for analysis. Clinical and pathological features were analyzed for association with outcome.

RESULTS

The 3- and 5-year survival rates of patients with SCLN metastasis were 16.5% and 16.5%, respectively. Multivariate analysis showed the serum level of squamous cell carcinoma antigen (SCC-Ag) < 15 ng/ml at initial diagnosis (p = 0.021) and staging/restaging including [18F] fluoro-2-deoxy-D-glucose positron emission tomography (FDG-PET) (p = 0.006) to be associated with a better prognosis.

CONCLUSION

Primary SCLN metastasis in cervical cancer is not incurable. The benefit from PET findings might help in selecting appropriate patients for curative primary and/or salvage treatment.

Peritoneal metastasis in primary cervical cancer: a case report

PURPOSE OF INVESTIGATION

Peritoneal metastasis presenting at initial diagnosis of squamous carcinoma of the uterine cervix is extremely rare. However, one such case was treated successfully with curative treatment.

CASE

A 43-year-old woman presented with FIGO Stage IVA cervical carcinoma and underwent concurrent chemoradiation (CCRT) with weekly cisplatin. During CCRT, she suffered from acute lower abdominal pain, high fever, and leukocytosis. Computed tomography (CT) favored a tubo-ovarian abscess, while [18F] fluorodeoxyglucose positron emission tomography (FDG-PET) showed a lesion midway between the umbilicus and symphysis pubis. An exploration by laparoscopy, an omental metastasis adhering to the bladder dome was excised. This patient finished CCRT encompassing the disease extent including the trochar sites and no evidence of disease was noted 50 months after initial diagnosis.

CONCLUSION

Though peritoneal metastasis above the pelvis seems ominous, curative treatment may still be viable in selected patients, even in surgical Stage IVB.

Chemical and microbiological qualities of The East River (Dongjiang) water, with particular reference to drinking water supply in Hong Kong

Currently, about 80% of drinking water in Hong Kong is abstracted from The East River (Dongjiang) that is located in the mainland side of China. Literature records and monitoring results of 2000-2001 confirmed that the lower section of the Dongjiang had been contaminated by organic and inorganic pollutants. Statistical analyses showed that the increases of total cadmium, copper and zinc in the surface layer of sediment of Hong Kong reservoirs from 1994 to 2001 were positively correlated (significant at p<0.05) with those in the surface layer of sediments of the lower Dongjiang. Recent microbiological survey revealed that pathogens such as Salmonella spp., Vibro spp., Giardia lamblia and Cryptosporidium parvum appeared occasionally in water samples of the Dongjiang and Hong Kong reservoirs. While analytical results found that currently most of the heavy metals, trace organics and microbes were removed by the drinking water treatment plants in Hong Kong, the long-term health risk of drinking water contamination should not be overlooked. The Water Supplies Department of Hong Kong is recommended to intensify its water quality monitoring program to cover pathogenic bacteria and parasites in watercourses and reservoirs.

Sarcoidosis of the gingiva--a case report

Involvement of oral tissues by sarcoidosis is uncommon. We present a case of sarcoidosis involving the gingivae of a 60-year-old woman. The patient presents with an 18-month history of localized areas of gingival redness and swelling. She also has a previous history of sarcoidosis.

'Sites' of resistance: alternative websites and state-society relations

Much attention has been focused on Singapore's attempt to use information technology to build a knowledge-based economy. This paper examines the implications of the unintended consequences of the Internet in the restructuring of state and society relations in Singapore. We use the data on Singapore-based and Singapore-related websites to show (a) the diversity of positions expressed by civil society organizations, fringe groups and even mainstream segments of society; (b) the negotiation process between the state and civil society over various rights and how developments in cyber-space have implications for 'reality'; (c) how censorship and content regulation itself is a more complex multi-dimensional process such that while local politics is regulated, the multi-ethnic character of the resident population has led to greater religious tolerance such that religious groups banned in some countries have found a safe haven in Singapore and have used the city-state as a strategic Internet node.

Chemical contamination of the East River (Dongjiang) and its implication on sustainable development in the Pearl River Delta

A recent survey reveals that water quality and river sediments of Dongjiang (the East River) have been mildly contaminated by heavy metals and organic chemicals, such as copper, lead, PCBs, PAHs and HCHs. According to photogrammertic surveys, the sources of contamination are closely related to human activities, such as domestic and industrial discharges, agricultural chemical applications and soil erosion due to deforestation. The level of water and sediment contamination is most serious at the mid-river section near the urban of Weizhou. Due to natural dilution and diffusion, the levels of contamination are slightly decreased at the medium low section of the River near Qiaotou and Matan. Nevertheless, the levels of contamination increase again in the lower river section near Shenzhen, which is a highly developed economic zone. Since Dongjiang is the major source of potable water supply for Hong Kong (nearly 80% of potable water of Hong Kong is abstracted from Dongjiang) and the other parts of the Pearl River Delta (PRD), such organic and inorganic pollution merit concern. Ironically, most of the industrial and commercial activities in the watershed of Dongjiang are business investments of Hong Kong citizens. Cross-border environmental efforts should be enhanced with collaboration of different jurisdictions to achieve targets of regional sustainability.

Organization of ribosomal RNA genes from a Loofah witches' broom phytoplasma

Using the technique of integrative mapping with three vectors carrying chromosomal rDNA sequences, one of two rRNA operons of loofah witches' broom (LfWB) phytoplasma was constructed. This is the first complete rRNA operon of a phytoplasma to be reported. The operon has a context of 5'-16S-23S-5S-3' with a tRNA(Ile) gene in the ITS and tRNA(Val) and tRNA(Asn) genes downstream from the 5S rRNA gene. Although the other operon has not been cloned, the DNA sequence of a PCR-amplified product shows that it has no tRNA(Ile) gene in the ITS region. The complete nucleotide sequences of 16S, 23S, and 5S rDNA are 1538, 2864, and 113 bp, respectively. Five -10-like sequences, but no -35 sequences, were found within a 494-bp leader region. There was a TG dinucleotide two nucleotides upstream from each -10-like sequence. The existence of a TG dinucleotide at this position has been reported to enhance the efficiency of a promoter without a -35 region. The regions immediately flanking the 5' and 3' ends of 16S and 23S rDNA can form long basepaired stems that contain sites for processing by RNase III. No obvious sequence for a rho-dependent or rho-independent termination site was found downstream from the tRNA(Asn) gene. The transcription may stop within a pyrimidine-rich region, as has been reported for several polypeptide-encoding genes and rRNA operons of archaeobacteria. The presence of the tRNA genes downstream from the 5S rRNA gene in the rRNA operon of LfWB phytoplasma further supports the hypothesis that phytoplasmas are phylogenetically closer to acholeplasmas than to mycoplasmas. The phylogenetic relatedness of LfWB phytoplasma to other phytoplasmas is discussed on the basis of the nucleotide sequence of rRNA genes and ITS.

The fliU and fliV genes are expressed as a single ORF in Salmonella choleraesuis

A DNA fragment carrying flagellar genes was cloned from Salmonella choleraesuis. Compared to the corresponding DNA fragment of Salmonella muenchen, this fragment contained three ORFs instead of four shown in S. muenchen. The DNA sequence data showed that there was an insertion of nucleotide C in the ORF of the S. choleraesuis fliU gene, which resulted in the disappearance of a termination codon downstream. The recombinant plasmid pFU11 containing the coding region of the fliU gene made by PCR on S. choleraesuis genomic DNA was constructed and expressed in Escherichia coli in the presence of IPTG. As expected, a 45 kDa protein band was observed on a SDS-PAGE gel, in contrast to two with each having about a half of the molecular weight. These results demonstrated that the DNA sequence encoding one protein (FliU) in S. choleraesuis corresponded to the DNA sequence encoding two proteins (FliU and FliV) in S. muenchen. The protein encoded by this single ORF might carry out the functions of two separated proteins by folding in such a way that its conformation could function like two interdependent protein subunits.

Meningococcal disease in South African goldmines--epidemiology and strategies for control

OBJECTIVES

To describe the epidemiology of meningococcal disease in South African goldmines and to suggest strategies for the prevention and control of further outbreaks.

DESIGN

We prospectively investigated a meningococcal outbreak that occurred in 1996 and describe the control measures that were implemented. In addition, we conducted a retrospective analysis of routinely collected data on meningococcal disease in these mines from 1972 to 1996.

SETTING

Four goldmines in Gauteng, employing 30,000 workers who live in hostels.

SUBJECTS

All cases of meningococcal disease at the mine hospital.

RESULTS

Between 1972 and 1976, 588 cases were diagnosed, with peaks in 1972 (203 cases, 727/100,000) and 1975 (147 cases, 564/100,000). Since 1978 less than 5 cases have been reported in most years, but smaller outbreaks occurred in 1990 (30 cases, 89/100,000) and 1996 (14 cases, 50/100,000). The 1996 outbreak (group A, clone I-1) was part of a larger outbreak in Gauteng that originated in Mozambique and began in one mine in July 1996, after which a mass vaccination campaign was implemented. This was followed by a smaller outbreak among non-vaccinated workers at an adjacent mine. Five patients were new recruits.

CONCLUSIONS

Despite a dramatic reduction in meningococcal disease over the last 25 years due mainly to changes in the work force, there are still outbreaks in this community. Those most at risk are young men who are new to the industry. Suggestions for prevention include effective surveillance, routine vaccination of new recruits and a rapid response to outbreaks, with mass vaccination and provision of chemoprophylaxis to close contacts.

Liquid phase parallel synthesis of guanidines

Combinatorial synthesis of N,N'-di(Boc)-Protected guanidines containing piperazine and pyrrolidine scaffolds has been developed. We initiate a preliminary study on the reactivity of several guanylating reagents with soluble polymer-bound diamines in liquid phase. Guanidines are liberated from the polymer support under mild conditions in high yields and high purity by simple precipitation and washings. This combinatorial liquid-phase methodology proves to be a useful tool for constructing guanidine libraries containing diamine scaffolds.

Meningitis in a community with a high prevalence of tuberculosis and HIV infection

OBJECTIVES

To evaluate the spectrum of aetiologies, and distinguishing clinical and laboratory features, of meningeal infection in a community with a high prevalence of tuberculosis (TB) and HIV infection.

SETTING

A hospital serving mineworkers, originating from rural areas of Southern Africa.

DESIGN

Prospective cohort of 60 consecutive lumbar punctures (LPs), performed for suspected meningitis.

MEASUREMENTS

Clinical history and examination; concurrent cerebrospinal fluid (CSF) and blood samples; mortality status six months after entry to study.

RESULTS

38 of 57 patients (66.7%) were HIV-1 positive, 59.5% of whom had a CD4 count <200 cells/mm3. Nine patients had tuberculous meningitis (TBM) and two had tuberculomas; four developed disease while on TB therapy. There was one case of multidrug, and two of isoniazid-resistant TBM. There were nine episodes of cryptococcal meningitis (seven patients), nine of aseptic meningitis, two of neurosyphilis and 20 normal LPs, including four with AIDS dementia complex (ADC). Ten patients with meningococcal infection, part of a larger outbreak, were significantly younger (p=0.004). All patients with tuberculous, cryptococcal (most immune-suppressed p<0.001) and aseptic meningitis were HIV-1 positive. Within six months, 19 patients had died. Death was associated with HIV positivity (p=0.004), low CD4 count (p<0.001) and a diagnosis of cryptococcal meningitis, CNS TB or ADC.

CONCLUSION

HIV has a major impact on the burden of disease and mortality, with a predominance of opportunistic chronic meningitides, despite a meningococcal outbreak, in this community. Of concern is the development of TBM despite therapy, and the emergence of drug-resistant strains.

Favorable scanning electron microscopic findings of stapled saphenous vein-carotid artery anastomoses

BACKGROUND

In the progress toward "off-pump" endoscopic coronary artery surgical procedures, new techniques for coronary artery anastomoses are being developed. One such approach is the use of nonpenetrating titanium clips. We evaluated the quality of anastomoses achieved using this technique in a porcine model of saphenous vein-carotid artery grafting using scanning electron microscopy.

METHODS

Bilateral saphenous vein-carotid artery interposition grafts were implanted in 10 "white race" pigs, using the nonpenetrating clips in one side of the neck and conventional hand suturing on the opposite side. One week after operation, the grafts were harvested.

RESULTS

All grafts were patent 7 days after operation, and 40 anastomoses underwent scanning electron microscopic study. In all samples, the luminal surfaces of both the carotid artery and vein graft were covered by a continuous layer of endothelial cells up to the anastomosis. Anastomotic sites in all clipped samples and most of the sutured anastomoses were completely endothelialized, and anastomotic clefts were indistinguishable. However, in 25% of sutured specimens, the suture material remained clearly visible inside the lumen of the vessel, and the subendothelial matrix remained exposed, with extensive fibrin, red blood cells, and platelet deposition on its surface.

CONCLUSIONS

Because the endothelial coverage consistently appeared to be complete and the subendothelial matrix was not exposed, it is likely that the risk of early anastomotic thrombosis is reduced by using the nonpenetrating titanium clips.

Single-voxel proton MR spectroscopy of nonneoplastic brain lesions suggestive of a neoplasm

BACKGROUND AND PURPOSE

MR spectroscopy is used to characterize biochemical components of normal and abnormal brain tissue. We sought to evaluate common histologic findings in a diverse group of nonneoplastic diseases in patients with in vivo MR spectroscopic profiles suggestive of a CNS neoplasm.

METHODS

During a 2-year period, 241 patients with suspected neoplastic CNS lesions detected on MR images were studied with MR spectroscopy. Of these, five patients with a nonneoplastic diagnosis were identified retrospectively; a sixth patient without tissue diagnosis was added. MR spectroscopic findings consistent with a neoplasm included elevated choline and decreased N-acetylaspartate and creatine, with or without detectable mobile lipid and lactate peaks.

RESULTS

The histologic specimens in all five patients for whom tissue diagnoses were available showed significant WBC infiltrates, with both interstitial and perivascular accumulations of lymphocytes, macrophages, histiocytes, and (in one case) plasma cells. Reactive astrogliosis was also prominent in most tissue samples. This cellular immune response was an integral component of the underlying disorder in these patients, including fulminant demyelination in two patients, human herpesvirus 6 encephalitis in one patient, organizing hematoma from a small arteriovenous malformation in one patient, and inflammatory pseudotumor in one patient. Although no histologic data were available in the sixth patient, neoplasm was considered unlikely on the basis of ongoing clinical and neuroradiologic improvement without specific therapy.

CONCLUSION

Nonneoplastic disease processes in the CNS may elicit a reactive proliferation of cellular elements of the immune system and of glial tissue that is associated with MR spectroscopic profiles indistinguishable from CNS neoplasms with current in vivo MR spectroscopic techniques. Such false-positive findings substantiate the need for histologic examination of tissue as the standard of reference for the diagnosis of intracranial mass lesions.

Fulminant progression of demyelinating disease after valproate-induced encephalopathy

We report the clinical, radiologic, and pathologic features of a patient who had fulminant demyelinating disease and who experienced acute progression of his disease after an episode of valproate-induced hyperammonemic encephalopathy. The role hyperammonemia played in the progression of the demyelination is uncertain. This case raises concern of a possible risk with the use of valproic acid in the subset of patients with fulminant demyelinating disease.

Contrast media of high and low molecular weights in the detection of recurrent herniated disks

PURPOSE

Our goal was to compare contrast enhancement of recurrent herniated disk fragments and scar after intravenous injection of a new high-molecular-weight contrast medium, Gadomer 17 (gadomer), with that after injection of a low-molecular-weight contrast medium, (gadopentetate dimeglumine).

METHODS

Recurrent herniated disks were modeled in dogs by placing a fragment of intervertebral disk cartilage in the epidural space at laminectomy. MR imaging was performed with one of the contrast media at 20 and 50 days and with the other medium at 22 and 52 days. The changes in signal intensity from baseline in the disk fragment and in the adjacent scar tissue was measured at 2, 22, and 45 minutes. Differences were tested for significance with a student t-test.

RESULTS

At 50 days after surgery, signal intensity in the intervertebral disk fragment increased by an average of 0.52 at 2 minutes after injection of gadomer and by an average of 0.90 after injection of gadopentetate. For scar, the increases in signal intensity were 1.41 (gadomer) and 1.62 (gadopentetate). At 22 and 45 minutes after injection, the signal intensity change in the disk fragment continued to be significantly greater after gadopentetate than after gadomer injection. In comparison with the changes at 50 days, both scar and disk fragment tended to show greater signal intensity changes at 20 days. Signal intensity changes in the disk fragments were significantly less after gadomer than after gadopentetate. Signal intensity changes in scar were slightly less with gadomer than with gadopentetate.

CONCLUSION

Greater contrast is achieved between scar and recurrent herniated disk with a higher-molecular-weight contrast medium than with one of lower molecular weight. The difference between the high- and low-molecular-weight contrast media increases with maturation of the scar tissue.

CuTira brachytherapy: a new combination of radioactive copper isotopes and the hypoxic cytotoxin, tirapazamine, for targeted tumor therapy

We previously showed a significant enhancement of tirapazamine-induced cytotoxicity and DNA damage after binding with copper. This result suggests that conjugates of tirapazamine with radioactive copper, i.e., 64Cu and 67Cu, may offer potential for targeted therapy of a wide range of advanced stage tumors including a possible treatment for patients with solitary hepatocellular carcinoma by intrahepatic arterial infusion. Major supporting considerations include: (a) tirapazamine having a high selective toxicity against hypoxic cells; (b) the nature of radioactive decay of these copper isotopes and obtainable high specific activity; and (c) simple procedure for the production of copper-tirapazamine complex.

Bilateral choroidal metastases as the initial presentation of a small breast carcinoma: a case report

Most ocular tumors metastasize from systemic origins in breast carcinoma in females, and bronchial carcinoma in males. Here, we report a case of choroidal carcinoma metastasis from the breast with visual problems being the only initial manifestations. In this case, both eyes were involved at almost the same time, with initial manifestation of blurred vision which progressed to complete visual loss. At first, the patient was diagnosed with malignant melanoma, and enucleation of the right eye was performed in another hospital. However, the tumor had already metastasized rapidly to numerous organs, including the lungs, brain and bone, although it had not affected the liver. Clinical presentations were, therefore, not compatible with those of malignant melanoma, which has usually been reported to metastasize to the liver. Persistent hypercalcemia and raised carcinoembryonic antigen (CEA) concentrations prompted investigations into the possibility of systemic malignancy. A very small breast nodule was finally located by thorough physical examination, and a lumpectomy was performed. A detailed review of the histopathology showed the tumors from the breast and the right eye to have the same origin. Simultaneous bilateral choroidal metastases from other malignancies is not uncommon; however, it is quite rare for breast carcinoma to present with visual problems as a first manifestation. Detailed history taking and physical examination are therefore essential when searching for a primary tumor, so that appropriate therapy can be given earlier.

Epstein-Barr virus LMP1 modulates the malignant potential of gastric carcinoma cells involving apoptosis

About 10% of gastric carcinomas including lymphoepithelioma-like carcinoma and adenocarcinoma are associated with Epstein-Barr virus (EBV) infection. In EBV-associated gastric carcinomas, the tumor cells express Epstein-Barr nuclear antigen 1 (EBNA-1) but not EBNA-2, -3A, -3B, or -3C, leader protein, or latent membrane proteins (LMPs) because of gene methylation. Only a few exceptional cases have LMP1 expression in tumor cells as demonstrated by immunohistochemical studies. To elucidate the biological effects of LMP1 and the significance of its restricted expression in EBV-associated gastric carcinomas, the LMP1 gene was transferred into EBV-negative gastric carcinoma cell lines (SCM1 and TMC1) and into EBV-negative nasopharyngeal carcinoma (NPC) cells (HONE-1) as a control. The biological effects of LMP1 in gastric carcinoma cells were monitored in vitro and in vivo. These results showed that the consequence of LMP1 expression is a growth enhancement in NPC cells, but it is a growth suppression in gastric carcinoma cells. The LMP1-expressing gastric carcinoma cells had a reduced growth rate, colony-forming efficiency, mean colony size, and tumorigenicity and a lower malignant cytological grade. The reduced growth rate, colony-forming efficiency, and mean colony size were partially reversible in vitro with treatment with LMP1 antisense oligonucleotide. In addition, enhanced apoptosis was found in the LMP1-expressing gastric carcinoma cells. This suggests that LMP1 may negatively modulate the malignant potential of gastric carcinoma cells via an enhancement of apoptosis. We concluded that the restriction of LMP1 expression in EBV-associated gastric carcinomas may lead to a growth advantage for tumor cells by avoiding LMP1 apoptotic effects and immunologically mediated elimination.

Cytochrome oxidase in Alzheimer's disease: biochemical, histochemical, and immunohistochemical analyses of the visual and other systems

Defects in oxidative metabolism have been implicated in Alzheimer's disease (AD). The present study evaluated the level of cytochrome oxidase (C.O.), an indicator of neuronal oxidative capacity, in various brain regions of post-mortem AD and control patients. We found a statistically significant reduction in C.O. levels in all cortical areas examined, including the primary and secondary visual cortices. In addition, all layers of the dorsal lateral geniculate nucleus and sublaminae of the primary visual cortex in AD cases examined suffered a reduction in their relative C.O. activity and protein amount. Our results suggest a generalized suppression of oxidative metabolism throughout the cortex, as well as in a major subcortical visual center in AD. Such hypometabolism may form the basis for not only deficits in higher cortical functions, but also a variety of visual dysfunctions known to occur in AD.

Malignant lymphomas of sinonasal region, including cases of polymorphic reticulosis: a retrospective clinicopathologic analysis of 34 cases

BACKGROUND

Lymphomas occurring in nasal cavities and paranasal sinuses are uncommon neoplasms in Western, but are reported to be higher in Oriental, countries. A retrospective study was performed to analyze the clinical and pathological characteristics of sinonasal lymphomas/polymorphic reticulosis at Taichung Veterans General Hospital during a 14-year period.

METHODS

At Taichung Veterans General Hospital, 37 patients with sinonasal lymphomas (including three patients with polymorphic reticulosis) were seen from November 1982 through September 1996. Excluding three patients without sufficient data, a total of 34 patients with their clinical records were reviewed. Clinical information regarding characteristics of the tumors, histological studies, treatment modalities and follow-up was collected for analysis.

RESULTS

The 34 patients who underwent review showed a male-to-female ratio of 2.1:1. Median age was 60 years (range 13-83 years). The most common symptoms were nasal obstruction, nasal discharge/rhinorrhea and epistaxis. Median duration of symptoms at the time of diagnosis was two months. The most frequently involved sites were nasal cavities (right more than left side). There were 31 non-Hodgkin's lymphomas and three polymorphic reticuloses. The pathological classifications revealed 13 diffuse large cell lymphomas, 14 diffuse mixed small and large cell lymphomas and four pleomorphic T-cell lymphomas. Of the 21 adequately staged patients, 13 patients were in stage I; four, stage II; two, stage III and two, stage IV. The immunophenotypic study was performed in 20 patients. Eighteen (90%) of them were T-cell lymphomas and only two cases (10%) derived from B-cell. Though approach to therapy and follow-up periods varied during the time period covered by this study, the differences in survival according to treatment modalities were not statistically significant. The follow-up period ranged from 9 days to 130 months. The mean survival was 84.2 months. The overall five-year survival rate was 63%.

CONCLUSIONS

The majority of the cases here were T-cell lymphomas. Most histologic grading by Working formulation belonged to the intermediate grade. Optimal treatment for such a group of patients still has no consensus, but adequate local control is important. If diagnosed and treated early, primary sinonasal lymphomas can be associated with a favorable outcome even with local treatment alone.