The value of MRI in quantification of parametrial invasion and association with prognosis in locally advanced cervical cancer: the "PLACE" study

OBJECTIVE

This retrospective observational study aims to evaluate the association between the extent of parametrial invasion (PMI) and disease-free survival (DFS) and cancer-specific survival (CSS) in patients with locally advanced cervical cancer (LACC).

MATERIALS AND METHODS

This study included patients with LACC showing parametrial invasion at Magnetic Resonance Imaging (MRI). They were treated with neoadjuvant chemo-radiotherapy (CT/RT) before undergoing radical hysterectomy. The staging MRIs were reviewed retrospectively. Measurements of maximum PMI (PMImax) and parametrial length were taken bilaterally. After that, PMIratio was calculated by dividing PMImax by parametrial length. Analysis was conducted on homogeneous subsets of patients, grouped based on their pathological lymph nodal evaluation (N- and N+). Correlations between PMImax and PMIratio with DFS and CSS were evaluated in both the N- and N+ groups, employing univariable Cox regression analysis.

RESULTS

Out of 221 patients, 126 (57%) had non-metastatic lymph nodes (N-), while 95 (43%) had metastatic lymph nodes (N+). The median observation period for all these patients was 73 months (95% confidence interval [CI]: 66-77). The 5-year DFS and CSS probability rates were 75% and 85.7%, respectively, for the N- group and 54.3% and 73.6%, respectively, for the N+ group. A higher PMImax (hazard ratio [HR] = 1.09) and PMIratio (HR = 1.04) correlated with worse overall survival in patients in the N- group (p = 0.025 and p = 0.042). These parameters did not show a significant statistical association in the N+ group.

CONCLUSIONS

The degree of PMI evaluated on MRI affects outcome in N- patients with LACC.

CLINICAL RELEVANCE STATEMENT

The degree of MRI parametrial invasion affects disease-free survival and cancer-specific survival in patients with the International Federation of Gynecology and Obstetrics (FIGO) stage IIB cervical cancer. This MRI finding can be easily incorporated into routine clinical practice.

KEY POINTS

• Visual assessment of parametrial invasion on MRI was not significantly associated with prognosis in locally advanced cervical cancer (LACC). • A greater degree of parametrial invasion is associated with poorer disease-free survival and cancer-specific survival in patients with LACC without metastatic lymph node involvement. • The degree of parametrial invasion at MRI has no correlation with prognosis in LACC with metastatic lymph nodes.

ARX Filtering of Single-Sweep Movement-Related Brain Macropotentials in Mono- and Multi-Channel Recordings

A technique of stochastic parametric identification and filtering is applied to the analysis of single-sweep event-related potentials. This procedure, called AutoRegressive with n exogenous inputs (ARXn), models the recorded signal as the sum of n+1 signals: the background EEG activity, modeled as an autoregressive process driven by white noise, and n signals, one of which represents a filtered version of a reference signal carrying the average information contained in each sweep. The other (n-1) signals could represent various sources of noise (i.e., artifacts, EOG, etc.). An evaluation of the effects of both artifact suppression and accurate selection of the average signal on mono- or multi-channel scalp recordings is presented.

Diffuse Cosmic Rays Shining in the Galactic Center: A Novel Interpretation of H.E.S.S. and Fermi-LAT γ-Ray Data

We present a novel interpretation of the γ-ray diffuse emission measured by Fermi-LAT and H.E.S.S. in the Galactic center (GC) region and the Galactic ridge (GR). In the first part we perform a data-driven analysis based on PASS8 Fermi-LAT data: We extend down to a few GeV the spectra measured by H.E.S.S. and infer the primary cosmic-ray (CR) radial distribution between 0.1 and 3 TeV. In the second part we adopt a CR transport model based on a position-dependent diffusion coefficient. Such behavior reproduces the radial dependence of the CR spectral index recently inferred from the Fermi-LAT observations. We find that the bulk of the GR emission can be naturally explained by the interaction of the diffuse steady-state Galactic CR sea with the gas present in the central molecular zone. Although we confirm the presence of a residual radial-dependent emission associated with a central source, the relevance of the large-scale diffuse component prevents to claim a solid evidence of GC pevatrons.

Conserved features of cancer cells define their sensitivity to HAMLET-induced death; c-Myc and glycolysis

HAMLET is the first member of a new family of tumoricidal protein-lipid complexes that kill cancer cells broadly, while sparing healthy, differentiated cells. Many and diverse tumor cell types are sensitive to the lethal effect, suggesting that HAMLET identifies and activates conserved death pathways in cancer cells. Here, we investigated the molecular basis for the difference in sensitivity between cancer cells and healthy cells. Using a combination of small-hairpin RNA (shRNA) inhibition, proteomic and metabolomic technology, we identified the c-Myc oncogene as one essential determinant of HAMLET sensitivity. Increased c-Myc expression levels promoted sensitivity to HAMLET and shRNA knockdown of c-Myc suppressed the lethal response, suggesting that oncogenic transformation with c-Myc creates a HAMLET-sensitive phenotype. Furthermore, HAMLET sensitivity was modified by the glycolytic state of tumor cells. Glucose deprivation sensitized tumor cells to HAMLET-induced cell death and in the shRNA screen, hexokinase 1 (HK1), 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 1 and hypoxia-inducible factor 1α modified HAMLET sensitivity. HK1 was shown to bind HAMLET in a protein array containing ∼8000 targets, and HK activity decreased within 15 min of HAMLET treatment, before morphological signs of tumor cell death. In parallel, HAMLET triggered rapid metabolic paralysis in carcinoma cells. Tumor cells were also shown to contain large amounts of oleic acid and its derivatives already after 15 min. The results identify HAMLET as a novel anti-cancer agent that kills tumor cells by exploiting unifying features of cancer cells such as oncogene addiction or the Warburg effect.

Exploring urban students' constructions about school, work, race, and ethnicity

This qualitative study is an exploration of 32 urban high school students' narratives about the connection between school, work, and societal expectations of their future success related to their racial and ethnic background. The sample varied along 2 contextual dimensions: participation in a psychoeducational intervention (Tools for Tomorrow) and developmental status (i.e., half the sample were 9th-grade students and the other half were 12th-grade students). Using consensual qualitative research, the narratives revealed 3 major domains: future orientation; students' perceptions of society's expectations based on race and ethnicity; and students' perception of the role of their race and ethnicity in future success. Results reveal that the majority of students endorse a connection between school and work, believe that society holds low expectations for them based on their racial and ethnic background, and cannot predict their future success based on their background.

[Cervix uteri lesions and human papiloma virus infection (HPV): detection and characterization of DNA/HPV using PCR (polymerase chain reaction]

The prevalence of human papillomavirus (HPV) genotypes was estimated by the polymerase chain reaction (PCR), in archival paraffin was embedded tissues. The case group consisted of 84 women aged 21-67 years (mean, 40 years) who were referred to the Department of Gynaecology (Oncology Centre, Coimbra) with citopathologically abnormal smears. This group was selected from a population of women who had undergone a screening programme (1990/94) in Central Region of Portugal. All these patients (n = 84) had a colposcopic directed cervical biopsy. HPV detection and typing was performed by the PCR method in the Department of Virology (National Health Care Institute, Lisbon). The prevalence of DNA/HPV found, concerning all epithelial cervical lesions studied and classified as squamous intra-epithelial lesions (SIL) and cervical cancer was 97.8%. On the basis of the data presented in this study, it was estimated that there was a statistically significant prevalence of low risk HPV types (HPV 6/11) in low grade SIL, 83.3%, and a statistically significant prevalence of high risk HPV types (HPV 16,18,31,33,51) in high grade SIL, 58.4%, as well as cervical cancer lesions in 100%. We conclude that there was a statistically significant difference between women with low and high grade SIL for HPV infection, with low and high risk HPV types, respectively. The risk factors for cervical cancer investigated (age at first sexual intercourse, multiple sexual partners, parity, use of oral contraceptives) were not associated to statistically significant differences concerning low grade SIL and high grade SIL. The clinical and therapeutic procedures were evaluated for the same five years (1990/94). It may be concluded that there would be no significant difference in clinical procedure for high grade lesions and cervical cancer, in which the treatment had been frequently radical (cone biopsies, simple or radical hysterectomy) and in which the HPV infection persisted frequently and was associated to high risk types (HPV 16 in 50% of these cases). On the other hand, it may be concluded that HPV detection in cervical biopsies, especially for low grade SIL lesions, which were evaluated in this study with a more conservative procedure (clinical evaluation only, punch biopsies, loop diathermy, CO2 laser vaporisation, cone biopsies), could identify women with high risk HPV types who might be at risk of developing dysplasia and cervical cancer.

Enantioselective Diels-Alder approach to C-3-oxygenated angucyclinones from (SS)-2-(p-tolysulfinyl)-1,4-naphthoquinone

Chiral racemic vinylcyclohexenes 2, bearing oxygenated substituents and/or a methyl group at the C-5 position of the cyclohexene ring, were submitted to Diels-Alder reactions with enantiomerically pure (SS)-(2-p-tolylsulfinyl)-1,4-naphthoquinone [(+)-1]. The domino cycloaddition/pyrolytic sulfoxide elimination process led to the formation of enantiomerically enriched angularly tetracyclic quinones anti-6 and syn-7, which were obtained from the kinetic resolution of the racemic diene. In all cases, (SS)-(2-p-tolylsulfinyl)-1,4-naphthoquinone reacted from the less hindered face of the more reactive s-cis conformation, to form products in good enantiomeric excesses. Steric effects and torsional interactions in the corresponding approaches account for the observed pi-facial diastereoselectivities at both partners. The usefulness of this methodology is illustrated with the four-step totally asymmetric synthesis of the C-3-oxygenated angucyclinone derivative (-)-8-deoxytetrangomycin 10 in 26% overall yield and with 50% enantiomeric purity.

Comparison between human and artificial neural network detection of Laplacian-derived electroencephalographic activity related to unilateral voluntary movements

A back-propagation artificial neural network (ANN) was tested to verify its capacity to select different classes of single trials (STs) based on the spatial information content of electroencephalographic activity related to voluntary unilateral finger movements. The rationale was that ipsilateral and contralateral primary sensorimotor cortex can be involved in a nonstationary way in the control of unilateral voluntary movements. The movement-related potentials were surface Laplacian-transformed (SL) to reduce head volume conductor effects and to model the response of the primary sensorimotor cortex. The ANN sampled the SL from four or two central channels overlying the primary motor area of both sides in the period of 80 ms preceding the electromyographic response onset in the active muscle. The performance of the ANN was evaluated statistically by calculating the percentage value of agreement between the STs classified by the ANN and those of two investigators (used as a reference). The results showed that both investigator and ANN were capable of selecting STs with the SL maximum in the central area contralateral to the movement (contralateral STs, about 25%), STs with considerable SL values also in the ipsilateral central area (bilateral STs, about 50%), and STs with neither the contralateral nor bilateral pattern ("spatially incoherent" single trials; about 25%). The maximum agreement (64-84%) between the ANN and the investigator was obtained when the ANN used four spatial inputs (P < 0.0000001). Importantly, the common means of all single trials showed a weak or absent ipsilateral response. These results may suggest that a back-propagation ANN could select EEG single trials showing stationary and nonstationary responses of the primary sensorimotor cortex, based on the same spatial criteria as the experimenter.

"Gating" of human short-latency somatosensory evoked cortical responses during execution of movement. A high resolution electroencephalography study

The present study aimed at investigating gating of median nerve somatosensory evoked cortical responses (SECRs), estimated during executed continuous complex ipsilateral and contralateral sequential finger movements. SECRs were modeled with an advanced high resolution electroencephalography technology that dramatically improved spatial details of the scalp recorded somatosensory evoked potentials. Integration with magnetic resonance brain images allowed us to localize different SECRs within cortical areas. The working hypothesis was that the gating effects were time varying and could differently influence SECRs. Maximum statistically significant (p<0. 01) time-varying gating (magnitude reduction) of the short-latency SECRs modeled in the contralateral primary motor and somatosensory and supplementary motor areas was computed during the executed ipsilateral movement. The gating effects were stronger on the modeled SECRs peaking 30-45 ms (N30-P30, N32, P45-N45) than 20-26 ms (P20-N20, P22, N26) post-stimulus. Furthermore, the modeled SECRs peaking 30 ms post-stimulus (N30-P30) were significantly increased in magnitude during the executed contralateral movement. These results may delineate a distributed cortical sensorimotor system responsible for the gating effects on SECRs. This system would be able to modulate activity of SECR generators, based on the integration of afferent somatosensory inputs from the stimulated nerve with outputs related to the movement execution.

Isolation and characterization of NUC70, a cytoplasmic, hematopoietic apoptotic endonuclease

Endonucleolytic DNA fragmentation is the common end point and the prevailing indicator of apoptosis. We have identified a 70-kDa endonuclease (NUC70) that is activated in drug-induced apoptosis of human hematopoietic cells. We purified NUC70 to homogeneity and generated a rabbit polyclonal antibody to distinguish it from previously identified nucleases. Biochemical characterization of isolated NUC70 demonstrates that it is Ca2+/Mg2+-dependent and active over a pH range of 6-8. When incubated with isolated HeLa nuclei, NUC70 was capable of generating internucleosomal DNA fragmentation. This endonucleolytic activity was inhibited by Zn2+, aurintricarboxylic acid, N-ethylmaleimide, spermine, and iodoacetamide. Western immunoblots using the anti-NUC70 antibody and DNA-SDS-polyacrylamide gel electrophoresis assays indicate that NUC70 expression and activity is restricted to human hematopoietic cells. No such activity was detected in human epithelial cell lines or murine hematopoietic cells. We also observed no difference in levels of NUC70 expression between apoptotic and nonapoptotic cells, suggesting that activation of NUC70 may be by posttranslational modification. We demonstrate that NUC70 activity is diminished in cells pretreated with the caspase inhibitors z-DEVD-fmk, z-VAD-fmk, and Z-CH2-Asp-DCB. Time course studies of cytoplasmic and nuclear endonuclease activities during apoptosis show that NUC70 is a cytoplasmic endonuclease that is translocated to the nucleus after the initiation of apoptosis. We confirmed this with immunostaining studies using anti-NUC70 antibody. These results demonstrate that NUC70 is an endogenous cytoplasmic endonuclease that is activated during apoptosis in a caspase-dependent mechanism.

Dynamic functional coupling of high resolution EEG potentials related to unilateral internally triggered one-digit movements

Between-electrode cross-covariances of delta (0-3 Hz)- and theta (4-7 Hz)-filtered high resolution EEG potentials related to preparation, initiation. and execution of human unilateral internally triggered one-digit movements were computed to investigate statistical dynamic coupling between these potentials. Significant (P < 0.05, Bonferroni-corrected) cross-covariances were calculated between electrodes of lateral and median scalp regions. For both delta- and theta-bandpassed potentials, covariance modeling indicated a shifting functional coupling between contralateral and ipsilateral frontal-central-parietal scalp regions and between these two regions and the median frontal-central scalp region from the preparation to the execution of the movement (P < 0.05). A maximum inward functional coupling of the contralateral with the ipsilateral frontal-central-parietal scalp region was modeled during the preparation and initiation of the movement, and a maximum outward functional coupling during the movement execution. Furthermore, for theta-bandpassed potentials, rapidly oscillating inward and outward relationships were modeled between the contralateral frontal-central-parietal scalp region and the median frontal-central scalp region across the preparation, initiation, and execution of the movement. We speculate that these cross-covariance relationships might reflect an oscillating dynamic functional coupling of primary sensorimotor and supplementary motor areas during the planning, starting, and performance of unilateral movement. The involvement of these cortical areas is supported by the observation that averaged spatially enhanced delta- and theta-bandpassed potentials were computed from the scalp regions where task-related electrical activation of primary sensorimotor areas and supplementary motor area was roughly represented.

Arginine butyrate downregulates p210 bcr-abl expression and induces apoptosis in chronic myelogenous leukemia cells

Downregulation of bcr-abl expression in the chronic myelogenous leukemia cell line K562 using antisense oligonucleotides has been shown to enhance the sensitivity of the cells to apoptotic stimuli, suggesting that p210 bcr-abl, like bcl-2 functions as an anti-apoptosis factor (McGahon A et al, Blood 1994, 83: 1179). In these experiments, the inhibition of p210 bcr-abl expression alone was not sufficient to induce apoptosis. We demonstrated that exposure to low doses (0.5 mM) of a butyric acid analog, arginine butyrate, was capable of inducing apoptosis in selected leukemia cell lines, including K562 cells, and in fresh leukemia cells from patients with chronic myelogenous leukemia. To further explore the mechanisms of this effect, we examined expression of p210 bcr-abl after butyrate exposure and found a dose-related inhibition of p210 bcr-abl protein without concordant change in other phosphoproteins, including the JAK-1 kinase. Further analysis revealed that the inhibition of bcr-abl expression occurs due to transcriptional regulation of the bcr-abl gene by arginine butyrate. These results suggest that arginine butyrate and other butyrate analogs alone or in combination may be useful in the therapy of patients with chronic myelogenous leukemia or bcr-abl expressing acute leukemias.

Improved realistic Laplacian estimate of highly-sampled EEG potentials by regularization techniques

In this study we investigated the effects of lambda correction, generalized cross-validation (GCV), and Tikhonov regularization techniques on the realistic Laplacian (RL) estimate of highly-sampled (128 channels) simulated and actual EEG potential distributions. The simulated EEG potential distributions were mathematically generated over a 3-shell spherical head model (analytic potential distributions). Noise was added to the analytic potential distributions to mimic EEG noise. The magnitude of the noise was 20, 40 and 80% that of the analytic potential distributions. Performance of the regularization techniques was evaluated by computing the root mean square error (RMSE) between regularized RL estimates and analytic surface Laplacian solutions. The actual EEG data were human movement-related and short-latency somatosensory-evoked potentials. The RL of these potentials was estimated over a realistically-shaped, magnetic resonance-constructed model of the subject's scalp surface. The RL estimate of the simulated potential distributions was improved with all the regularization techniques. However, the lambda correction and Tikhonov regularization techniques provided more precise Laplacian solutions than the GCV computation (P < 0.05); they also improved better than the GCV computation the spatial detail of the movement-related and short-latency somatosensory-evoked potential distributions. For both simulated and actual EEG potential distributions the Tikhonov and lambda correction techniques provided nearly equal Laplacian solutions, but the former offered the advantage that no preliminary simulation was required to regularize the RL estimate of the actual EEG data.

Responses of human primary sensorimotor and supplementary motor areas to internally triggered unilateral and simultaneous bilateral one-digit movements. A high-resolution EEG study

We modelled the responses of human primary sensorimotor areas and supplementary motor area to simple, self-initiated unilateral and simultaneous bilateral middle finger movements using a novel high-resolution electroencephalography technology. The results support the view that these cortical motor areas are involved in parallel and present similar activity in the preparation, initiation, and execution of the contralateral and bilateral movements. Furthermore, the left primary sensorimotor area (dominant hemisphere) appears to be activated more than the right primary sensorimotor area during the preparation and performance of the ipsilateral movements.

Human short latency cortical responses to somatosensory stimulation. A high resolution EEG study

Human short-latency cortical responses to median nerve stimulation were investigated with a new high resolution electroencephalography technology that markedly enhanced spatial details of somatosensory-evoked potentials (SEPs). Maximum amplitude potentials were estimated over contralateral and/or frontal-mesial scalp regions about 20, 22, 24, 26, 30, 32 and 45 ms following the stimulation. Frontal-lateral P20-N24-N30-P45 and parietal-lateral N20-P24-P30-N45 showed dipolar patterns, whereas frontal-mesial N24-N30-P45 and central-lateral P22-N26-N32-P45 presented no clearcut dipole counterpart. Plausibly, the spatially enhanced frontal-parietal SEP components were generated (tangential dipoles) within the lateral central sulcus cortex, and anticipated the central-lateral and frontal-mesial components generated (radial dipoles) from the crown of the pre- and/or post-central gyri and the supplementary motor area, respectively.

A high resolution EEG method based on the correction of the surface Laplacian estimate for the subject's variable scalp thickness

To improve the spatial resolution of human event-related potentials, we developed a new high resolution EEG method based on the improved estimate of the realistic surface Laplacian (SL). The novelty of this method consisted in the computation of the local scalp resistance that was assumed to be inversely proportional to the local scalp thickness measured from magnetic resonance images of the subject's head. The local scalp thickness was then multiplied by the SL estimate of the potential over a realistic magnetic resonance-constructed model of the subject's scalp surface. The new method was applied on human movement-related and somatosensory-evoked potentials, the SL estimate at a constant scalp thickness being used as a reference. The locally-predicted scalp thickness was significantly (P < 0.05) higher in the temporal areas (9.5 +/- 2.6 mm) than in the parieto-occipital (6.6 +/- 1.3 mm) and frontal (4.8 +/- 1.1 mm) areas. Compared to the SL estimate at constant scalp thickness, the improved SL estimate enhanced the spatial detail of both movement-related and somatosensory-evoked potentials.

Topography of spatially enhanced human short-latency somatosensory evoked potentials

In the present study modern high resolution electroencephalography (EEG) was used to spatially enhance human median nerve short-latency somatosensory evoked potentials (SEPs). It was shown that the spatially enhanced N30 consisted of two frontal subcomponents, one located in the frontal-lateral area of the scalp, the other located in the frontal-mesial area. Both of these subcomponents were most reduced in amplitude (or disappeared) during concomitant hand movement ipsilateral to the stimulus, but were differentially influenced by executed contralateral movement and imagined ipsilateral movement. These results support the hypothesis of an involvement of the frontal-mesial cortex (including the supplementary motor area) in the generation of the frontal N30.

High resolution EEG: a new model-dependent spatial deblurring method using a realistically-shaped MR-constructed subject's head model

This paper presents a new model-dependent method for the spatial deblurring of scalp-recorded EEG potentials based on boundary-element and cortical imaging techniques. This model-dependent spatial deblurring (MDSD) method used MR images for the reconstruction of the subject's head model, and a layer of 364 radially-oriented equivalent current dipoles as a source model. The validation of the MDSD method was performed on simulated potential distributions generated from equivalent dipoles oriented radially, obliquely, and tangentially to the head surface. Furthermore, this method was used to localize neocortical sources of human movement-related and somatosensory-evoked potentials. It was shown that the new MDSD method improved markedly the spatial resolution of the simulated surface potentials and scalp-recorded event-related potentials. The spatial information content of the scalp-recorded EEG potentials increased progressively by increasing the spatial sampling from 28 to 128 channels. These results indicate that the new method could be satisfactorily used for high resolution EEG studies.

Human cortical activity related to unilateral movements. A high resolution EEG study

In the present study a modern high resolution electroencephalography (EEG) technique was used to investigate the dynamic functional topography of human cortical activity related to simple unilateral internally triggered finger movements. The sensorimotor area (M1-S1) contralateral to the movement as well as the supplementary motor area (SMA) and to a lesser extent the ipsilateral M1-S1 were active during the preparation and execution of these movements. These findings suggest that both hemispheres may cooperate in both planning and production of simple unilateral volitional acts.

Spline Laplacian estimate of EEG potentials over a realistic magnetic resonance-constructed scalp surface model

This paper presents a realistic Laplacian (RL) estimator based on a tensorial formulation of the surface Laplacian (SL) that uses the 2-D thin plate spline function to obtain a mathematical description of a realistic scalp surface. Because of this tensorial formulation, the RL does not need an orthogonal reference frame placed on the realistic scalp surface. In simulation experiments the RL was estimated with an increasing number of "electrodes" (up to 256) on a mathematical scalp model, the analytic Laplacian being used as a reference. Second and third order spherical spline Laplacian estimates were examined for comparison. Noise of increasing magnitude and spatial frequency was added to the simulated potential distributions. Movement-related potentials and somatosensory evoked potentials sampled with 128 electrodes were used to estimate the RL on a realistically shaped, MR-constructed model of the subject's scalp surface. The RL was also estimated on a mathematical spherical scalp model computed from the real scalp surface. Simulation experiments showed that the performances of the RL estimator were similar to those of the second and third order spherical spline Laplacians. Furthermore, the information content of scalp-recorded potentials was clearly better when the RL estimator computed the SL of the potential on an MR-constructed scalp surface model.

Performances of surface Laplacian estimators: a study of simulated and real scalp potential distributions

This paper presents a study of the performance of various local and spherical spline methods currently in use for the surface Laplacian (SL) estimate of scalp potential distributions. The SL was estimated from simulated instantaneous event-related scalp potentials generated over a three-shell spherical head model. Laplacian estimators used planar and spherical scalp models. Noise of increasing magnitude and spatial frequency was added to the potential distributions in order to simulate noise presumed to contaminate scalp-recorded event-related potentials. A comparison of noise effects on various Laplacian estimates was made for increasing number of "electrode" positions in variants of the 10-20 system. Furthermore, to evaluate the error due to the use of unrealistic scalp models, the matching between SL estimates of human scalp-recorded movement-related potentials computed on spherical and realistically-shaped MRI-constructed models of the scalp was examined. With all methods the error of the SL estimate increased proportionally with the magnitude and spatial frequency of noise. Increased number of "electrodes" up to 256 significantly reduced the error (p < 0.05). In general, the best SL estimates were computed by second and third order splines including lambda correction, the performances of the second order spline being better with more than 64 "electrodes". Compared with spline Laplacians, the best local methods provided nearly equal estimates with low spatial sampling (19 and 28 "electrodes"), as well as high spatial frequency noise. The error of the SL estimate due to unrealistic scalp model was significant, and it augmented with increased spatial sampling from 64 to 128 electrodes.

Reduction of ocular artefacts in source current density brain mappings by ARX2 filtering

Sweep by sweep analysis of event-related potentials (ERP) of the human scalp represents a reliable tool for both the diagnosis of neurologic diseases and the study of the central nervous system during cognitive tasks. The off-line procedure based on stochastic parametric identification and filtering herewith described, allows an accurate analysis of single-sweep ERP and a drastic reduction of ocular artefacts variously propagating through the skull. Moreover, the spatial distribution of the recorded ERP in bidimensional form was enhanced by using the Laplacian operator in order to get an estimate of the source current density (SCD) flow from the skull into the scalp. Complete single-trial signals were filtered according to an autoregressive model of signal generation with 2 exogenous inputs (ARX2). The ARX2 procedure models the recorded signal as the sum of three signals: (a) the background EEG activity, modelled as an autoregressive process driven by a white noise; (b) a filtered version of a reference signal carrying the average information contained in each sweep; (c) a signal due to the ocular artefact propagation. The evaluation of the effect of artefact suppression on those channels close to the eyes was compared with standard ordinary least squares method (OLS) based on a linear model of the influence of EOG on ERP. Finally, the better results obtainable through ARX filtering on sweep-by-sweep brain mappings are also presented.

Statistical analysis of topographic maps of short-latency somatosensory evoked potentials in normal and parkinsonian subjects

This work had the following objectives: i) to integrate temporal analysis (N30 peak) with power-spectrum topographic mapping of short-latency somatosensory evoked potentials (SEP's) recorded in parkinsonian and normal control subjects; and ii) to analyze with a new statistical approach the between-group topographical differences in both the time and frequency domains. The principal aim was to better determine the topography of the scalp frontal areas where the amplitude of the N30 wave was previously found to be significantly reduced in parkinsonians. The statistical procedure was based on the combined use of descriptive data analysis (DDA) and multivariate analysis. In the context of DDA, an improved version of significance probability mapping (SPM) was used by which it is possible to evaluate homo- and nonhomoscedastic data with parametric tests. The statistical evaluation of between-group differences was performed with the multivariate Hotelling's T2 test and the associated post hoc test. With this statistical procedure, it was possible to determine that the between-group statistical differences in both the temporal and power spectrum distributions were localized only in midline and contiguous contralateral frontal areas of the scalp.

ARX filtering of single-sweep movement-related brain macropotentials in mono- and multi-channel recordings

A technique of stochastic parametric identification and filtering is applied to the analysis of single-sweep event-related potentials. This procedure, called AutoRegressive with n eXogenous inputs (ARXn), models the recorded signal as the sum of n+1 signals: the background EEG activity, modeled as an autoregressive process driven by white noise, and n signals, one of which represents a filtered version of a reference signal carrying the average information contained in each sweep. The other (n-1) signals could represent various sources of noise (i.e., artifacts, EOG, etc.). An evaluation of the effects of both artifact suppression and accurate selection of the average signal on mono- or multi-channel scalp recordings is presented.

Making arm movements within different parts of space: dynamic aspects in the primate motor cortex

The activity of 176 individual cells in the arm area of motor cortex (areas 4 and 6) was studied while monkeys made arm movements of similar direction within different parts of extrapersonal space. The behavioral paradigm used was a 3-dimensional reaction-time task aimed at dissociating the direction of movement, which remained similar across the work space, from the patterns of muscular activity and the angular joint excursions necessary to perform these movements. In agreement with other studies (Georgopoulos et al., 1982; Schwartz et al., 1988), we found that, within a given part of space, the activity of 169 (96.0%) cells studied increased most for a given preferred direction and less for other directions of movement. This change was graded in an orderly fashion. We further analyzed the orientation in space of the cells' preferred directions under the differing conditions of the task. We found that, as movements with similar trajectories were made within different parts of space, the cells' preferred directions changed spatial orientation. This change was of different magnitudes for different cells, but at the level of the population, it followed closely the changes in orientation of the arm necessary to perform the movements required by the task. Movement population vectors (Georgopoulos et al., 1983, 1986, 1988) computed from cell activity proved to be good predictors of movement direction regardless of where in space the movements were performed. These results indicate that motor cortical cells can code direction of movement in a way which is dependent on the position of the arm in space. The data are discussed in relation to the existence of mechanisms which facilitate the transformation between extrinsic and intrinsic coordinates. These transformations are necessary to perform arm movements to visual targets in space.

Computerized mapping system of cerebral evoked potentials

The introduction of computerized analysis systems in the study of bioelectrical signals is enhancing the understanding of the physiological mechanisms which underlie cerebral evoked potentials (EPs) in response to externally applied stimuli. In the present study, short latency (0-50-ms) and long latency (0-500-ms) somatosensory evoked potentials (SEPs) were recorded by 32 scalp electrodes from normal and pathological subjects during median nerve stimulation. An interpolation procedure for estimating data values between the neighboring electrodes allowed the mapping of cortical activity across the scalp. Time signals were also transformed by an FFT algorithm and frequency maps obtained following the same interpolation procedure. Temporal and frequency maps were graphically displayed using color and three-dimensional plots. The usefulness of computerized topographical analysis is discussed; the time and frequency computer maps obtained from the same subjects are compared and their relative advantages are evaluated.

Immunohistochemical analysis of the immune reaction in the nervous system in paraneoplastic encephalomyelitis

We examined frozen sections of frontal cortex, medulla, and dorsal root ganglia from a patient with small-cell lung cancer and paraneoplastic encephalomyelitis, involving the medulla and dorsal root ganglia, with a panel of antibodies reactive for IgG, IgM, C3, B cells, T cells, T cell subsets, macrophages, and class I and II (HLA-DR) major histocompatibility complex (MHC) antigens. We detected an antineuronal antibody (anti-Hu) in the serum and CSF of the patient and found deposits of IgG in the periphery of some neurons in dorsal root ganglia. The infiltrates were almost exclusively T cells with a predominance of CD8-positive cells. Neurons did not express class I or II MHC antigens. Satellite cells in the dorsal root ganglia from the patient and controls were HLA-DR-positive. These data indicate that CD8-positive T cells predominate in the inflammatory infiltrates of paraneoplastic encephalomyelitis. IgG deposits may be relevant in the damage of the sensory neurons.

Abnormalities of short-latency somatosensory evoked potentials in parkinsonian patients

Twenty-two patients (16 affected by parkinsonian syndromes, 6 by other neurological diseases) and 12 age-matched controls were examined. Short-latency somatosensory evoked potentials were recorded from 30 scalp electrodes in the 45-52 msec following separate left and right median nerve stimulation at the wrist. Bit-colour maps were generated on a 4096 pixel matrix via quadratic interpolation. Peak latencies and amplitudes of the parietal, central and frontal components were evaluated. Moreover, the amplitude ratios between parietal and frontal components on the same hemiscalp and between peaks on homologous right and left scalp districts were taken into account. The unique significant difference between parkinsonians and controls was represented by a depressed frontal N30 wave. This peak was absent in 3 and reduced in 7 out of 16 parkinsonians, with an overall abnormality rate of 47% of the examined arms. Average maps pooling data of parkinsonians and controls confirmed the presence of reduced evoked activity for the whole duration of wave N30 on those mid- and parasagittal frontal districts where this peak is maximally represented in normals. A similar abnormality was found in 1 of the 6 non-parkinsonian neurological patients suffering from a meningioma of the falx compressing the left supplementary motor area. Possible pathophysiology of such wave N30 abnormalities in parkinsonians is discussed.

Short latency somatosensory evoked responses to median nerve stimulation in healthy humans: electric and magnetic recordings

Somatosensory Evoked Potentials (SEPs) and Somatosensory Evoked magnetic Fields (SEFs) to median nerve stimulation at wrist were recorded in 5 healthy subjects and the components between 15 and 30 ms after the stimulus were evaluated on the hemiscalp contralateral to the stimulated wrist. SEPs were measured by means of a 32-channel recorder and compared with SEFs obtained via multiple measurements with a 4-channel sensor. Equivalent dipole localization was carried out for the magnetic components peaking at about 15, 20 and 24 ms. The scalp distribution of SEPs, illustrated by bit mapped color images, were qualitatively explained by three separate sources. The first is described as a tangentially oriented dipole placed behind the Central Sulcus and responsible for the parietal N20-"late P25" waves and for the frontal P20-N30 ones. The second is represented by a radieal dipole placed just in front of the Central Sulcus and pointing towards the motor strip, responsible for the rolandic P22 component. The third is just behind the Central Sulcus and is radieally oriented towards the surface of the postcentral sensory area for the "early P25" parietal wave. The SEFs distributions, illustrated by color isofield contour maps, were quantitatively explained by a unique tangential dipole localized, with good resolution, well behind the Sulcus for the 15 ms waves and slightly frontal to this site for the waves peaking at around 20 and 24 ms. The equivalent dipole has been localized at a depth of about 5 cm (15 ms component), 2 cm (20 ms components) and 4 cm (24 ms component), across the studied subjects. It is stressed that the dipole responsible for the magnetic pattern is likely to be the same tangential dipole responsible for a part of the electric pattern. Due to their radieal orientation, the other two dipoles, proposed for the SEPs maps, would be mostly undetectable by a magnetic investigation.

Central nervous system involvement demonstrated by immunological study in prolymphocytic variant of chronic lymphocytic leukemia

A patient with the prolymphocytic variant of B cell chronic lymphocytic leukemia (CLL/PL) who developed meningeal leukemic involvement is reported. He had been diagnosed as having CLL/PL 2.5 years earlier, and treated successively with splenectomy, continuous chlorambucil and CHOP chemotherapy. While receiving the latter treatment, the patient developed persistent cephalalgia and vomiting, without signs of neurological focality. A lumbar puncture yielded a cerebrospinal fluid (CSF) showing lymphoid cells of prolymphocytic appearance and the immunological cell markers demonstrated the clonality of these cells. Intrathecal methotrexate and arabinosyl cytosine treatment was administered, this leading to the disappearance of the abnormal cells from the CSF and the resolution of the clinical symptoms.

Callosal and association neurons in the cortical space: a spectral analysis approach

The tangential distributions of callosal neurons of area 5 projecting homotopically to the contralateral hemisphere and of association neurons of areas 4 and 6 projecting to ipsilateral area 5 were determined in the macaque monkey by using neuroanatomical methods based on the retrograde transport of horseradish peroxidase. Both distributions were studied qualitatively through 2-dimensional reconstructions of the cortical areas of origin and quantitatively through a spectral analysis. This approach facilitated the characterization of the spatial periodicities contained in these distributions revealing that, in area 5, callosal neurons were organized in bands of various shapes and width; these bands were composed of more discrete clusters of cells. In the frontal lobe, association neurons projecting to ipsilateral area 5 were arranged similarly. This study suggests that a common principle underlies the tangential organization of both callosal and association projecting cells in different cortical areas and emphasizes a basic similarity of interhemispheric and intrahemispheric connections.

Abnormal Na+-K+ ATPase kinetics in a subset of essential hypertensive patients

We have performed a kinetic analysis of the interaction of Na+-K+ ATPase with internal Na+ in erythrocytes of 30 normotensive controls and 72 essential hypertensive patients. Neither the maximal rate of ouabain-sensitive sodium efflux (Vmax) nor the internal Na+ content required for half-maximal stimulation (K50%) were significantly different between normotensive and hypertensive patients. Nevertheless, using the 95% confidence limits of the K50% in the normotensive group as a cut-off point, 13 (18.06%) essential hypertensive patients exhibited increased values of this parameter (29.16 +/- 4.31 mmol l-1 cells) revealing decreased affinity of Na+-K+ ATPase for internal Na+ (Pump-hypertensives). The Vmax was also higher in the Pump '-' subset (14.08 +/- 4.85 mmol (1 cells h)-1 vs. 6.92 +/- 1.80; P = 0.0002) and 10 of these 13 hypertensives exhibited a Vmax above the upper end limit of 10.5 mmol (1 cells h)-1, suggesting a compensatory effect. No differences were observed between the Pump '-' subset and the remaining 59 hypertensives without Na+-K+ pump abnormality when basal erythrocyte Na+ content and clinical parameters of hypertension were examined. Decreased apparent affinity of Na+-K+ pump for internal Na+ present in 9-27% of essential hypertensives may be implicated in pathogenetic mechanisms of hypertension.

Corticocortical efferent systems in the monkey: a quantitative spatial analysis of the tangential distribution of cells of origin

The laminar and tangential distributions of association neurons projecting from areas 4 and 6 of the frontal lobe to area 5 of the superior parietal lobule were studied in macaque monkeys by using horseradish peroxidase histochemistry. In both areas 4 and 6 association neurons were medium-large pyramidal cells of layers II and III, and pyramidal and fusiform cells of layers V-VI. Tangentially, they were distributed unevenly over the cortical surface occupying only certain parts of areas 4 and 6, including the dorsomedial part of area 6, the proximal arm region of Woolsey's M1 map, parts of the postarcuate cortex, and the supplementary motor area. Within these projection zones, the number of projection cells waxed and waned in a periodic fashion. Quantitative methods, including spectral analysis techniques, were used to characterize precisely spatial periodicities along the rostrocaudal dimension. The same quantitative analyses were used to determine the nature of the tangential distribution of corticocallosal cells of area 5 projecting to contralateral area 5. Both association and callosal spectra contained a strong component in the range of low spatial frequencies, corresponding to periods greater than 2 mm. Moreover, a consistent peak was observed in both spectra at spatial frequencies corresponding to periods ranging from 0.85 to 1.28 mm. This peak is in accord with the hypothesis of a modular organization of the cells of origin of these projection systems.

Pyramidal influences on ventral thalamic nuclei in the cat

In pericruciate cortex-ablated 'pyramidal cats', discharge changes in single neurons of ventral thalamic nuclei were studied, following stimulation of ipsilateral medullary (MPT) and contralateral cervical (CPT) pyramidal tract. It was seen that cells in ventrolateral nucleus, ventroanterior nucleus and ventromedial nucleus were not significantly (2.2%) modified by impulses coming from MPT and CPT. Conversely, a very high percentage (58.8%) of cells in ventrobasal complex (VB) responded to MPT stimulation (64.4% in ventroposterolateral nucleus, VPL, and 40.7% in ventroposteromedial nucleus, VPM). A considerable number (34.8%) of VPL cells responsive to MPT, were influenced by CPT, while none of the cells in VPM were. The most frequent effect observed in VB neurons, on MPT and CPT stimulation, was excitation followed by depression of discharge.