Changes in pain perception and pain-related somatosensory evoked potentials in humans produced by exposure to oscillating magnetic fields

cDNA selection was used to isolate coding sequences from cosmids mapping to the gene-rich telomeric region of human chromosome 21q. A novel cDNA, termed SMT3A, was isolated and mapped between the loci PFKL and D21S171, about 2.2 Mb proximal to the telomere. The predicted protein of 103 amino acids appears to be a homologue of the Saccharomyces cerevisiae SMT3 protein, whose gene was previously isolated as a suppressor of mutations in the MIF2 gene. The yeast MIF2 gene encodes an essential centromeric protein and shows homology to mammalian CENP-C, an integral component of active kinetochores. SMT3A was found to be highly homologous to two other recently isolated human genes, suggesting the presence of a new gene family. Homologous sequences were also found in protozoa, metazoa, and plants. Moreover, all predicted proteins show significant homology to ubiquitin. The proposed role of yeast SMT3 as centromeric protein and the strong evolutionary conservation of the SMT3A gene suggest an involvement of the encoded protein in the function and/or structure of the eukaryotic kinetochore.     

Somatosensory evoked magnetic fields following passive finger movement

RATIONALE AND OBJECTIVES: The author introduces a number of techniques well known in exploratory pattern recognition that can be used for the analysis of the shape of metacarpophalangeal profiles. It is shown that the classic Q-scores must be adapted for such techniques to be applicable. METHODS: A new set of scores (P-scores) describing the shape of metacarpophalangeal profiles is derived. The application of various pattern-recognition techniques that use P-scores is described, using a collection of metacarpophalangeal length measurements in patients with various pathologic conditions. RESULTS: Different pattern-recognition techniques highlight different aspects of the profiles, which, when interpreted together, yield a consistent understanding of the data set and insight in individual patients' peculiarities. CONCLUSIONS: The use of scale-invariant scores is imperative when the shape of profiles is to be analyzed, especially in data sets with large variations in the scale factor. Methods of pattern recognition using such scores are of potential clinical interest.     

Auditory evoked magnetic fields in cases with temporal lobe glioma

Auditory evoked magnetic field (AEF) is known to be suitable to separate left and right hemispheric activities while auditory evoked potential is not. To evaluate cortical auditory function in ten patients with temporal lobe gliomas, we measured AEF for monaural tone stimuli using a helmet-shaped 66-channel MEG system. Latency of the N 100 m, the most prominent peak with a latency around 90 ms, was measured in the hemisphere contralateral to the stimulus onset. In five patients, the N 100 m latency was within our normal range (mean +/- 2 s.d.). In these five cases, tumor was located in the anterior or the inferior part of the temporal lobe. We observed significant delay of the N 100 m latency in four patients and disappearance of the N 100 m in another patient. In the later five patients, tumor extended to the superior and posterior part of the temporal lobe. AEF can be used to evaluate cortical auditory function noninvasively in cases with temporal lobe gliomas.     

Interhemispheric asymmetry exists in female in the N100m source position of the auditory evoked magnetic fields

OBJECTIVE: To evaluate the affect of families' attitudes about the appropriateness of discussing psychosocial concerns on pediatric providers' identification of psychosocial problems. DESIGN: These data were collected as part of the Greater New Haven Child Health Study, New Haven, Conn. The study design was a prospective cohort. SETTING: Families were recruited from a stratified random sample of all primary care practices in the greater New Haven area. Nineteen of 23 invited practices agreed to participate including 2 prepaid practices, 2 neighborhood health centers, and 7 fee-for-service group and 8 fee-for-service solo practices. PARTICIPANTS: All families of children aged 4 to 8 years who attended these practices during 2 separate 3-week periods (1 in fall 1987 and 1 in spring 1988) were invited to participate in the study. Families were invited to participate only once, on the first contact with any eligible child, using approved procedures. Of 2006 eligible families, 1886 (94%) chose to participate. MAIN OUTCOME MEASURE: The outcome variable for these analyses is the identification of any behavioral, emotional, or developmental problem by the pediatrician on the 13-category checklist. Overall, pediatric clinicians identified 27.5% of children with 1 or more psychosocial problems. RESULTS: Our data suggest that there is a great deal of discrepancy between what parents report is appropriate to do when their children have psychosocial problems and what they actually do when they recognize such problems in their children. Most (81.1%) believed it was appropriate to discuss 4 or more of the 6 hypothetical situations with their children's physician, while only 40.9% actually did discuss any of these problems with a physician when a problem occurred. Given the correlates of parents who intended to discuss such problems (higher education, older age, Euro-American ethnicity, higher income, married, availability of medical insurance) the possibility that parents are providing socially acceptable responses to such questions seems likely. Further, our data indicate that parents' actual reports of discussions of psychosocial problems is unrelated to whether physicians identified those problems in children. CONCLUSIONS: Pediatricians'judgments about the presence of psychosocial problems in their young patients seem to be based on their own observations rather than on what parents report. Physician-parent communication about psychosocial problems will be increasingly important as primary care physicians assume their role as gatekeepers to more expensive services such as mental health interventions.     

Cerebral evoked responses to gastrointestinal stimulation in humans

Recent advances have permitted recording of evoked potentials (EPs) in response to electrical and mechanical stimulation of the gastrointestinal (GI) organs via methods used primarily in clinical neurophysiology. Current research involving stimulation of the esophagus, rectum, and colon, and recording the corresponding responses on the scalp, is being practiced in only a few laboratories. This review examines the engineering aspects of recording EPs, such as characteristics of the stimuli, placement of stimulus electrodes in the GI tract, and enhancement of evoked potential signals. We also discuss the physiological concepts involved in the generation of EPs, and how these compare with somatosensory evoked responses. Current experimental techniques employed by various investigators and results reported from their laboratories are compared. We believe that cerebral EPs to GI stimulation could be useful in studying a number of pathophysiological conditions such as gastroesophageal reflux disease, diffuse esophageal spasm, chronic inflammatory bowel disorders, chronic abdominal pain, and irritable bowel syndrome, among others. We hope that the present review will generate interest in the use of EPs arising out of GI stimulation, aiding in understanding their physiological implications in healthy subjects and in GI disorders.     

Locomotor-like movements evoked by leg muscle vibration in humans

We attempted to elicit automatic stepping in healthy humans using appropriate afferent stimulation. It was found that continuous leg muscle vibration produced rhythmic locomotor-like stepping movements of the suspended leg, persisting up to the end of stimulation and sometimes outlasting it by a few cycles. Air-stepping elicited by vibration did not differ from the intentional stepping under the same conditions, and involved movements in hip and knee joints with reciprocal electromyogram (EMG) bursts in corresponding flexor and extensor muscles. The phase shift between evoked hip and knee movements could be positive or negative, corresponding to 'backward' or 'forward' locomotion. Such an essential feature of natural human locomotion as alternating movements of two legs, was also present in vibratory-evoked leg movements under appropriate conditions. It is suggested that vibration evokes locomotor-like movements because vibratory-induced afferent input sets into active state the central structures responsible for stepping generation.     

Gamma-range activity evoked by coherent visual stimuli in humans

We tested the hypothesis of a role of gamma-range synchronized oscillatory activity in visual feature binding by recording evoked potentials from 12 subjects to three stimuli: two coherent ones (a Kanizsa triangle and a real triangle) and a non-coherent one (a Kanizsa triangle in which the inducing disks had been rotated so that no triangle could be perceived). The evoked potentials were analysed by convoluting the signal for each subject and each stimulation type by Gabor wavelets centred from 28 up to 46 Hz, providing a continuous measure of frequency-specific power over time. A first peak of activity was found around 38 Hz and 100 ms with a maximum at electrode Cz in each experimental condition. A second peak of activity occurred around 30 Hz and 230 ms, with a maximum at O1 in response to the real triangle and a maximum at Cz in the case of the illusory triangle. At 100 ms we did not find any variations of the gamma-band component of the evoked potential with stimulation type, but the power of the 30 Hz component of the evoked potential between 210 and 290 ms differed from noise only in the case of a coherent triangle, no matter whether real or illusory. We thus found a 30 Hz component whose power correlates with stimulus coherency, which supports the hypothesis of a functional role of high-frequency synchronization in feature binding.(ABSTRACT TRUNCATED AT 250 WORDS)     

Cortical activation during fast repetitive finger movements in humans: steady-state movement-related magnetic fields and their cortical generators

OBJECTIVE: To study the cortical physiology of fast repetitive finger movements. METHODS: We recorded steady-state movement-related magnetic fields (ssMRMFs) associated with self-paced, repetitive, 2-Hz finger movements in a 122-channel whole-head magnetometer. The ssMRMF generators were determined by equivalent current dipole (ECD) modeling and co-registered with anatomical magnetic resonance images (MRIs). RESULTS: Two major ssMRMF components occurred in proximity to EMG onset: a motor field (MF) peaking at 37+/-11 ms after EMG onset, and a postmovement field (post-MF), with inverse polarity, peaking at 102+/-13 ms after EMG onset. The ECD for the MF was located in the primary motor cortex (M1), and the ECD for the post-MF in the primary somatosensory cortex (S1). The MF was probably closely related to the generation of corticospinal volleys, whereas the post-MF most likely represented reafferent feedback processing. CONCLUSIONS: The present data offer further evidence that the main phasic changes of cortical activity occur in direct proximity to repetitive EMG bursts in the contralateral M1 and S1. They complement previous electroencephalography (EEG) findings on steady-state movement-related cortical potentials (ssMRCPs) by providing more precise anatomical information, and thereby enhance the potential value of ssMRCPs and ssMRMFs for studying human sensorimotor cortex activation non-invasively and with high temporal resolution.     

The silent period between sounds has a stronger effect than the interstimulus interval on auditory evoked magnetic fields

Lymphocyte activation remains an area of intense interest to immunologists and cell biologists and the dynamics of expression of surface molecules during the process are widely studied. The CD69 C-type lectin is reportedly the earliest activation antigen on lymphocytes and can be detected within hours of mitogenic stimulation. Recently reports have described differential activation dynamics with respect to different antigenic or mitogenic stimuli. This study has investigated the dynamics of CD69 expression over time after mitogenic, allogeneic, cytokine and target cell mediated activation of T-cell and NK cell subsets. It is apparent that the dynamics of CD69 expression differ with respect to the cell type and the method of stimulation. Mitogenic stimulation resulted in the most rapid expression of CD69 on both T- and NK cells while alloantigen stimulation induced a far slower response. Target cell stimulation of NK cells gave paradoxical results in that the CD69 + ve subset increased as a proportion of the total NK cells but did not increase in number. This was due to the selective binding of CD69 - ve NK cells to the target cells and their subsequent loss from the lymphoid gate. We confirmed this by showing that CD69 + ve NK cells do not lyse K562 target cells. This observation demonstrates the caution needed in the analysis of flow cytometric data based solely upon relative proportions of cells within discrete subsets.     

Abnormalities of auditory evoked magnetic fields and structural changes in the left hemisphere of male schizophrenics--a magnetoencephalographic-magnetic resonance imaging study

Functional and structural changes in 10 DSM-III-R male schizophrenics and 10 healthy volunteers were investigated using magnetoencephalographically (MEG) detected long-latency (N100 m) auditory evoked fields (AEFs) and magnetic resonance imaging (MRI). The AEFs were characterized by single moving equivalent dipoles, which were superimposed on MRIs. There were significant differences in dipole orientations and in AEF latencies in the left hemisphere of schizophrenics, when compared to the controls. The MEG-detected alterations were found to be associated with a bilateral volume reduction of the posterior superior temporal gyrus (pSTG), which was more pronounced in the left hemisphere. Separate analysis of white and gray matter has shown that the pSTG volume reduction resulted from decreased gray matter volumes without white matter changes. Both the functional and the morphological data indicate a left-hemispheric disturbance in our patients.     

Somatosensory evoked potentials during hypoxia and hypocapnia in conscious humans

PURPOSE: The objective of the study was to evaluate the effects of moderate hypoxia and hypocapnia on the latency and amplitude of cortical somatosensory evoked potentials (SSEPs) in conscious human subjects. METHODS: In ten volunteers the amplitude and latency of the cortical somatosensory evoked potentials were recorded during stimulation of the left posterior tibial nerve. Measurements of SSEPs and respiratory variables were made breathing ambient air, air containing a reduced oxygen percentage (17% O2, 14% O2 (n = 6) or 11% O2 (n = 10)), and again during voluntary hyperventilation breathing ambient air (PETCO2 = 20 mmHg, n = 10). RESULTS: Hypoxia (11% O2) caused mild stimulation of ventilation (P < 0.05) but had no effects on the latency or amplitude of the SSEP. Lesser degrees of hypoxia had no effects. Hyperventilation caused a small (2-4%) decrease) in the latency of the SSEP and an increase in the amplitude of the SSEP (P < 0.05). CONCLUSIONS: These findings in conscious subjects were consistent with previous observations in anaesthetized humans and anaesthetized dogs and show that the decrease in latency of the SSEP associated with hypocapnia is not due to changes in the depth of anaesthesia. These effects of hypocapnia may contribute to small variations in the latency of the SSEP when monitoring is performed during surgery, but are unlikely to be large enough to be of clinical concern.