Neutrophil (PMNL) function defects occur as a consequence of HIV infection. This study examined PMNL apoptosis in patients with the acquired immunodeficiency syndrome (AIDS) to determine if accelerated apoptosis contributes to impaired function. PMNL were isolated from 10 HIV-infected patients with CD4 ϩ lymphocyte counts Ͻ 200/mm 3 without signs of active infection and 7 healthy volunteers. PMNL were stained with acridine orange and ethidium bromide after 0, 3, 6, and 18 h in culture, and examined for the morphologic changes of apoptosis and viability by fluorescent microscopy. Apoptosis was also demonstrated by electron microscopy, flow cytometry, and DNA gel electrophoresis.Apoptosis was minimal at 0 h, but PMNL from AIDS patients exhibited significantly greater apoptosis than controls at 3 h (22.5 Ϯ 11.5 vs. 8.9 Ϯ 6.9%, P ϭ 0.015), 6 h (38.1 Ϯ 14.2 vs. 18.1 Ϯ 4.5%, P ϭ 0.003), and 18 h (71.3 Ϯ 19.0 vs. 38.8 Ϯ 16.7%, P ϭ 0.002). Viabilities were Ն 88.0% for both groups from 0-6 h, but by 18 h viability was significantly decreased for the HIV group (58.8 Ϯ 12.4 vs. 83.5 Ϯ 10.4%, P ϭ 0.001) due to an increase in non-viable apoptotic cells. Incubation with serum from AIDS patients had no effect on control PMNL, and incubation with control serum did not reduce the rate of apoptosis of PMNL from AIDS patients. Incubation with granulocyte colony-stimulating factor (G-CSF) in vitro significantly decreased apoptosis for PMNL from AIDS patients.PMNL from patients with AIDS exhibit markedly accelerated apoptosis ex vivo. In vivo, apoptosis and functional impairment of PMNL may contribute to the risk of secondary infections, and cytokine therapy may be of potential clinical benefit in this circumstance. ( J. Clin. Invest. 1996. 98:2714-2719.)

Body surface Laplacian electrocardiogram (ECG) mapping using a set of disk electrodes is explored by both computer simulation and human experiments in 12 healthy subjects. The Laplacian ECG was estimated from body surface potentials using finite difference estimation algorithms. The performance of the finite difference Laplacian estimators was evaluated by both computer simulation and human experiments. The present experimental results show that the two types of finite difference Laplacian estimates are highly correlated and have a consistent spatial distribution over the anterolateral chest during normal ventricular activation. The present computer simulation and human experiment results suggest the feasibility of estimating the body surface Laplacian maps (BSLMs) from potentials using the finite difference algorithm over the anterior chest in male subjects. The noise levels of the BSLMs over the anterolateral chest were quantitatively compared to the noise levels in corresponding body surface potential maps (BSPMs) in 12 healthy subjects. The simulation and experiment results indicate that the noise to signal ratios in the BSLMs over the anterolateral chest during ventricular activation is about 5 times that of the BSPMs, when no signal processing is performed.

Body surface Laplacian ECG (LECG) has demonstrated its enhanced capability to localize cardiac electrical sources closest to the recording site. The aim of the present study was to evaluate the noise level and signal to noise ratio (SNR) in the LECG as compared to the potential ECG (PECG). Such evaluation is important to determine the applicability of the LECG to localizing and imaging of cardiac electrical activity in an experimental setting. Experimental studies were conducted in six healthy men. A 150-channel PECG was recorded from the anterolateral chest and the LECG was estimated using the finite difference algorithm. The noise level in the PECG and LECG was evaluated using multiple estimation protocols. The signal level during ventricular depolarization and repolarization was also estimated, and the corresponding SNR was calculated. Different filtering techniques were examined to evaluate their effects on the noise level and SNR of the LECG and PECG. The experimental results indicate that with basic signal processing techniques (baseline adjustment, three-point moving average filter, and Wiener spatial filter), the SNR of the LECG is about 30-40% of that of the PECG. Furthermore, the SNR estimated during ventricular depolarization is about three times that obtained during ventricular repolarization for the PECG and LECG. The present study indicates that the LECG derived from the PECG using a local finite difference estimation procedure has satisfactory SNR during the periods of ventricular depolarization and repolarization, and suggests the feasibility of estimating the LECG from the recorded PECG in human subjects in an experimental setting.

3D-EEG rhythm mapping was performed to study alpha desynchronization using the ZeroCrossings analysis (ZCA) method. 32ch EEGs were recorded from 5 healthy volunteer subjects ranging from 21 to 36 years old during relaxed eye-closed state with flash light stimulation (at lHz, IOHz, and 40Hz inter-stimulus intervals).These EEG signals were filtered for the alpha band (8.0-14.OHz) using a fast Fourier transform based digital filter. From thresholded Zero-Crossing points, periodic intervals of the alpha waves were determined and converted to instantaneous frequencies (IFS). The power spectrum of the IF fluctuation plot during a 8 1.92 sec length of recorded EEG was calculated and plotted. From the power spectrum of an IF plot, information regarding the rhythm of the waveforms and of the envelopes, which is not represented in the filtered alpha waveforms alone, can be extracted. The spectrum slope values (SSVs) of the best-fit inclination lines for the frequencies of interest on the power spectrum were determined. Finally, 3-D EEG rhythm mapping displayed the scalp distribution of SSVs to show regions of synchronized or desynchronized alpha activity.We can observe the spatial dynamics of the alpha rhythm during flash stimulation using over-minute recordings. 3-D EEG rhythm mapping is useful in the investigation of cortical structures and the interactions of the underlying rhythmic activity.

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