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Biomedical subjects

P Teale

Publications and source records attributed to P Teale.

At least 19 recordsLinked to original sources
PubMed1997

Magnetic source imaging evidence of sex differences in cerebral lateralization in schizophrenia.

BACKGROUND: It has been postulated that schizophrenia represents a disorder of anomalous cerebral lateralization. This study is a replication of earlier preliminary findings using a multichannel neuromagnetometer, suggesting altered lateralization in schizophrenia in male subjects, with an extension of the findings to female subjects. METHODS: We used magnetoencephalography-based magnetic source imaging to estimate the intracranial location of the 100-millisecond latency auditory-evoked field component (M100) in both left and right hemispheres of 20 patients with paranoid schizophrenia and 20 controls without schizophrenia. Neuroanatomical data were obtained by means of magnetic resonance imaging, from which we segmented and computed volumes of both total brain and left and right superior temporal gyri. RESULTS: Locations of M100 source were compatible with neuronal generators located in the transverse gyri of Heschl on the superior temporal gyri in both study groups; M100 sources were asymmetric in all the control subjects. The male patient subgroup exhibited significantly less asymmetry than the control group, while the female patient subgroup actually showed significantly more asymmetry. The male patient subgroup generally had smaller superior temporal gyri than the control group. No evidence of total brain volume differences was observed. CONCLUSIONS: Our findings support previous magnetoencephalography-based studies suggesting anomalous cerebral lateralization in schizophrenia. Further, in extending our studies to female patients, our data suggest that the nature of this anomaly is sex specific, a finding that, to our knowledge, has not previously been reported.

Adult↗
PubMed1997

Cortisol concentrations in post competition horse urine: a French and British survey.

The purpose of the present report was to estimate the population parameters of cortisol concentrations in urine, an endogenous hormone used as a 'doping' agent and for which an international threshold (1.0 micrograms/ml) has been proposed. Two data bases (French and UK) corresponding to 112 and 142 samples, respectively were considered. Urine was collected under specific post competition conditions. Cortisol concentrations were obtained by validated methods (HPLC for the French samples, and GC-MS for UK samples). No difference was observed between the 2 data sets and statistical analyses were carried out on the two merged files. The overall geometric mean cortisol concentration was 48 ng/ml. Distribution was not Gaussian. A log-normal distribution was not rejected (for P > 0.05). Using the log-normal distribution, it was calculated that the probability of exceeding a cortisol concentration in urine of 1.0 micrograms/ml was 1.1 x 10(-4). It was concluded that the actual international threshold is specific i.e. robust with regard to the risk of erroneously declaring an unmedicated horse as positive.

Animals↗
PubMed1997

Sex-specific expression of Heschl's gyrus functional and structural abnormalities in paranoid schizophrenia.

OBJECTIVE: Evidence supports abnormal temporal lobe structure and function in schizophrenia. Some abnormalities, particularly involving the auditory cortex, appear to be sex specific. These findings were extended to anatomical and physiological descriptors. METHOD: The authors quantified the volume, surface area, and three-dimensional location of Heschl's gyri on magnetic resonance imaging (MRI) images of 21 patients with paranoid schizophrenia and 24 healthy comparison subjects. Neuromagnetic localizations of the 100-msec latency auditory evoked field (M100) were compared with MRI-determined locations of Heschl's gyri, computed as the geometric center of mass of the volume. RESULTS: Volumetric measures revealed small Heschl's gyri only in male patients. Asymmetry was found in the location of the Heschl's gyrus centroid (more anterior on the right) across all groups. Male comparison subjects had M100 locations posterior to the Heschl's gyrus centroid in the left hemisphere and close to the Heschl's gyrus centroid on the right, while male patients had M100 sources anterior to the Heschl's gyrus centroid on the left. All women had M100 locations posterior to the Heschl's gyrus centroid on the left and anterior to it on the right. CONCLUSIONS: These results demonstrate that some temporal lobe abnormalities in schizophrenia are sex specific. They also suggest that the anomalous lateralization of the auditory evoked field cannot be explained by a shift in the underlying anatomy, since the anatomical substrate is lateralized in both comparison subjects and patients of both sexes. These findings may indicate a sex-specific functional reorganization in the auditory cortex in schizophrenia.

Adult↗
PubMed1996

Reproducibility of MEG auditory evoked field source localizations in normal human subjects using a seven-channel gradiometer.

Magnetoencephalographic (MEG) auditory evoked fields (EF) were recorded from 12 normal adult subjects over both hemispheres on two separate occasions at least one week apart using a seven-channel second-order gradiometer. Stimuli were computer-generated at 25-msec duration, 1 kHz tone pips. Responses to 100 stimuli were averaged, and source estimates with confidence intervals were computed, for the 100-msec latency auditory EF component, termed M100. Root-mean-squared (rms) differences in x, y, and z locations were approximately 0.7 cm on the two occasions; strength and orientation differences were 18 nA-m and 11 degrees, respectively. This spatial accuracy using a seven-channel instrument, compares favorably with other currently available technologies for localization of brain function.

Adult↗
PubMed1995

Cerebral laterality in homosexual males: preliminary communication using magnetoencephalography.

MEG-based auditory M100 source location in the left and right hemispheres of 8 strictly homosexual and 9 strictly heterosexual males were compared to determine if this measure of interhemispheric laterality varies as a function of sexual orientation. MEG fields evoked by auditory tone pips were recorded from left and right hemispheres in response to contralateral ear stimulation. The source of the 100-msec latency component, generated in the superior temporal gyrus, was estimated using a least squares inverse solution algorithm. Auditory sources in heterosexual men were significantly further anterior in the right hemisphere compared to the left hemisphere. Source locations in the homosexual men did not exhibit significant interhemispheric asymmetry, being similarly located in both hemispheres. Findings suggest an anatomic and/or functional difference in the superior temporal gyrus of at least some homosexual men.

Adult↗
PubMed1995

MEG based brain laterality: sex differences in normal adults.

Magnetoencephalographic (MEG) auditory evoked fields produced by short tone pips were recorded from 34 normal adults (17 males, 17 females) and the 100 msec latency component (M100) localized in left and right hemispheres. Absolute M100 location in the antero-posterior dimension was calculated for each subject. M100 sources were significantly further anterior in the right hemisphere of males. Magnetic resonance (MR) based anatomy of the superior temporal gyri (STG) in a subset of 17 subjects showed that in the left STG of both males and females M100 sources were located approximately midway on the STG. In the right hemisphere of males, however, M100 sources were significantly further anterior on the STG than was the case for females. The findings are compatible with a sex based difference in right STG functional anatomy, with evidence of greater hemispheric lateralization in males compared to females based upon a predominantly right hemisphere contribution.

Adult↗
PubMed1995

Schizophrenia may alter neuromagnetic representations of attention.

When male paranoid schizophrenic subjects attended to a dichotic oddball task requiring target discrimination, their 100-ms latency left hemisphere magnetic auditory sources did not increase in strength, and their source geometry appeared to be degraded, rather than enhanced, compared with normal control subjects, implicating abnormal processing in the superior temporal gyrus.

Adult↗
PubMed1995

Analysis of endogenous human endothelin peptides by high-performance liquid chromatography and mass spectrometry.

The three isoforms of both endothelin (ET) and big ET are not readily distinguishable by radioimmunoassay (RIA) or enzyme-linked immunosorbent assay (ELISA) alone. We have previously used high-performance liquid chromatography (HPLC) linked with RIA to determine ET isoforms in various tissue extracts, and cell supernatants. Our aim was to confirm that the isoforms of ET secreted by human umbilical vein endothelial cells (HUVECs) are ET-1 and big ET-1, using HPLC linked to electrospray mass spectrometry (ESI-MS). Authentic synthetic peptide standards were used to obtain the specific ions for ET isoforms and to calculate their retention times on the HPLC system. ET-1, [Met7]-sulfoxy ET-1, ET-2, ET-3, and big ET-1 could all be separated by HPLC and by specific ions on ESI-MS. Pooled supernatant (500 ml) from 50 cultures of HUVECs was applied first to an anti-C-terminal ET-1 immunoaffinity column and then to an anti-C-terminal big ET-1 immunoaffinity column. The eluates were solid phase-extracted and then injected onto an HPLC system linked to ESI-MS. Peaks of mass intensity at the specific ions and retention times corresponding to ET-1, [Met7]-sulfoxy ET-1, and big ET-1 were found in these eluates. However, no signal was present for ET-2 or ET-3. These data confirm that HUVECs in culture produce ET-1, [Met7]-sulfoxy ET-1, and big ET-1.

Cells, Cultured↗
PubMed1994

Magnetic auditory source imaging in macaque monkey.

We recorded magnetic auditory evoked fields from the left hemisphere of a 2-year-old 3.4 kg Macaca nemestrina monkey. Three separate components were isolated from each of three data sets with latencies of approximately 22 ms, 46 ms, and 130 ms after stimulus onset. The 46 ms latency component had clear extrema values and was selected for localization. Field values from 21 recording points were used to estimate the 3-D source location of the 46 ms latency component, termed the M46. High resolution MR images of the brain provided information for correlation of neuroanatomic structure with source location. The neuroanatomic source was found to lie in the superior aspect of the temporal lobes bilaterally. We believe the M46 is the macaque analog of the human M100. Recording of auditory evoked fields in nonhuman primates offers a valuable animal model for studying neurophysiology of human magnetoencephalographically (MEG) determined auditory sources.

Acoustic Stimulation↗
PubMed1994

Auditory M100 component 1: relationship to Heschl's gyri.

This study was designed to localize the neuroanatomic generator of the 100 ms latency magnetic auditory evoked field (EF) component (M100) activated by an unattended tone pip. Magnetic EFs in response to 25 ms duration, 90 dB, 1 kHz tone pips were recorded from both hemispheres of nine normal adults, five males and four females, using a seven-channel second-order gradiometer. The source of the M100 was estimated, with confidence intervals, by a least squares based inverse solution algorithm. Magnetic resonance (MR) images of the brain were acquired with a 1.5 T system using a standard head coil. The superior temporal gyri (STG) were manually segmented from 1.7 mm thick coronal images, and the superior surfaces were then rendered from the 3-D volume data. Translation and rotation matrices were identified to locate the magnetoencephalography (MEG) determined sources within the reconstructed STGs. This population of 18 STGs in 9 individuals demonstrated two transverse gyri in 4 of 9 left hemispheres, and 5 of 9 right hemispheres. All 9 left hemisphere M100 sources were in or included Heschl's gyrus(i) in the confidence intervals. Seven of the 9 included Heschl's gyrus(i) on the right: the remaining two, both males, had sources slightly anterior to Heschl's gyrus(i). We conclude that all M100 source location estimates were compatible with an auditory koniocortex source in or adjacent to Heschl's gyri.

Adult↗
PubMed1993

Neuropsychological test performance and MEG-based brain lateralization: sex differences.

Magnetoencephalographic (MEG) auditory evoked fields (EF) were recorded from left and right hemispheres of 9 normal males and 12 normal females. Source location of the 100 ms latency component (M100) was localized to superior temporal lobes bilaterally using an inverse solution algorithm. All subjects also were administered the Wechsler block design and visual reproduction subtests, and the California Verbal Learning Test (CVLT). M100 source locations demonstrated significant sex differences in interhemispheric asymmetry. Males had source locations further anterior than females, with the differences most pronounced in the right hemisphere. Expected sex differences were found in neuropsychological test performance, with males performing better on block design ad visual reproduction, and females performing better on the CVLT. Across both sexes, block design scores correlated significantly with right hemisphere M100 location, with more anterior source locations associated with better performance. CVLT scores were negatively correlated with right hemisphere M100 source locations. These findings suggest MEG-based measures of interhemispheric asymmetry may be related to specific neuropsychological test performance measures.

Acoustic Stimulation↗
PubMed1993

ELISA screening with GC-MS confirmation of the tranquilizer chlorprothixene administered in subtherapeutic doses to horses.

A commercially available generic promazine ELISA kit is available which shows cross-reactivity for the tranquilizer chlorprothixene (CPT). The ELISA test readily detects the presence of CPT or its metabolites in equine urine for up to 24 h after the i.v. and i.m. administration of sub-therapeutic doses (4.5 mg) to three horses. Maximum concentrations (CPT equivalents) are obtained 2 h after i.v. dosing. No distinct concentration peak values are observed after i.m. administration. Following solid-phase extraction, confirmation of CPT and its metabolites by electron impact mass spectrometry after sub-therapeutic administration is not successful. The use of chemical ionization mass spectrometry however revealed the presence of at least four metabolites including; chlorprothixene sulphoxide, hydroxylated chlorprothixene and hydroxylated chlorprothixene sulphoxide.

Animals↗
PubMed1992

Auditory magnetic source localization in twins.

We recorded magnetoencephalographic (MEG) auditory evoked fields (EF) from the L and R hemispheres of 12 paris of twins, 6 monozygotic (MZ), and 6 dizygotic (DZ) and localized the source of the 100 msec latency EF component termed the M100. M100 sources exhibited greater similarity in location in MZ twin pairs, especially in the L hemisphere. These findings support the hypothesis that the functional location of processing of nonmeaningful unattended auditory stimuli may depend more heavily on left hemisphere structures. Furthermore, genetic effects are evident in these left hemisphere structures and their activity, as is a substantial amount of environmental variance.

Acoustic Stimulation↗
PubMed1991

The development of a gas chromatographic/mass spectrometric screening procedure to detect the administration of anabolic steroids to the horse.

A screening procedure for anabolic steroid residues in horse urine has been developed based upon solid-phase extraction and gas chromatographic/mass spectrometric analysis in the selected ion mode. For moderate sample throughput the method provides a viable alternative to radioimmunoassay screening and has advantages over the latter technique due to its flexibility, specificity and ability to detect a number of steroids in a single analysis. Full automation of the gas chromatographic/mass spectrometric analysis is an additional feature of the methodology.

Anabolic Agents↗
PubMed1991

Magnetic auditory M100 source location in normal females.

We recorded magnetoencephalographic auditory evoked fields from the left and right hemispheres of six normal adult female subjects, in response to unattended tone pips. Magnetic field data was used to estimate location, orientation, depth, and strength of the 100-ms latency evoked field component (M100). M100 source locations did not significantly differ in left and right hemispheres. Previous studies in six normal males demonstrated M100 sources to be significantly further anterior in the right hemisphere. Compared to the previously reported male subjects, M100 sources in the right hemisphere of these females were significantly further posteriorly, by a mean value of 2.1 cm. These findings, while preliminary, support sex-related functional and/or structural differences in the superior temporal lobe, and would be compatible with the female right temporal planum extending further posteriorly. They suggest MEG recordings may be a useful addition to studies of sex-related difference in brain function and/or structure.

Adult↗