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PubMed1992

CSF chromogranin A-like immunoreactivity in schizophrenia: relationships with REM latency and slow wave sleep.

Chromogranin A (CgA) is a calcium binding protein and a precursor of modulatory peptides in the brain. We measured CgA-like immunoreactivity (CgA-LI) in cerebrospinal fluid (CSF) in 15 male schizophrenic patients (diagnosed by DSM-III-R criteria) after 3 nights of polysomnography. Patients had been drug free for at least 33 days. Our earlier report that CSF CgA-LI in schizophrenic patients correlated significantly with negative symptoms and ventricle-brain ratios, which have been related to slow wave sleep, raised the possibility that CgA-LI might relate to slow wave sleep. CSF CgA-LI was significantly correlated with stage 4 sleep and rapid eye movement latency. Whether these positive relationships between CSF CgA-LI and electroencephalographic sleep measures are specific for schizophrenia awaits further study.

Adult↗

PubMed1989

Effect of prenatal lignocaine on auditory brain stem evoked response.

To test the hypothesis that there would be a positive correlation between the interpeak wave (I-V) interval as measured by auditory brain stem evoked response and the ratio of umbilical cord blood arterial to venous lignocaine concentrations in infants born after maternal epidural anaesthesia, 10 normal infants born at full term by elective caesarean section were studied. Umbilical cord arterial and venous plasma samples were assayed for lignocaine, and auditory brain stem evoked responses were elicited at 35 and 70 dB at less than 4 (test 1) and greater than or equal to 48 hours (test 2). Mean wave I-V intervals were prolonged in test 1 when compared with test 2. Linear regression showed the arterial:venous ratio accounted for 66% (left ear) and 43% (right ear) of the variance in test 1 intervals. No association was found in test 2. In newborn infants, changes in serial auditory brain stem evoked response tests occur after maternal lignocaine epidural anaesthesia and these changes correlate with blood lignocaine concentrations.

Anesthesia, Epidural↗

PubMed2001

Exposure to short-lasting impulse noise causes microglial and astroglial cell activation in the adult rat brain.

Exposure to impulse noise, i.e. pressure waves, is above a certain intensity, harmful to auditory function. Intense, short-lasting impulse noise of 198 or 202 dB affects the heavy subunit of neurofilament proteins in neuronal perikarya of the cerebral cortex and hippocampus. There was as well an increased expression of immediate early gene products and induction of neuronal apoptosis. Here, we show that this range of exposure also affects glial cells. We identified microglial cells with an antibody against the complement receptor type 3 (OX-42) and astrocytes with an antibody against the glial fibrillary acidic protein (GFAP). The pattern of damage included microglial activation as early as 2 h after exposure to 202 dB. The activation increased further at 18 h. There was a significant increase of the area occupied by microglial cells in the anterior and posterior hypothalamus and in the lateral septal nucleus. Astrogliosis was observed in the cerebral cortex, the dentate gyrus and in the pyramidal cell layers as well as in white matter of the hippocampus. Both the microglial and astrocytic reactivities remained at 21 days. Exposure to 198 dB, caused similar, but less prominent activation in both cell types.

Journal Article↗

PubMed1993

[Clinical neurological findings in brain-dead patients].

Most of university hospitals have their own criteria for brain death, based on the national criteria. Here the term "brain death" has been restricted to cases with irreversible deep coma and lack of spontaneous respiration secondary to "total destruction of the brain" for which the cause of the primary brain disease should be known and the most vigorous treatments have been given in vain. In evaluating patients with brain death, careful and accurate neurological examinations are mandatory. The level of consciousness should be in deep coma even after deep painful stimuli, without any movements including decorticate and decerebrate postures. The absence of spontaneous respiration is a crutial determinant for the diagnosis. The more sophisticated apnea testing has been standardized for clinical use. This will be discussed by another speaker. However, unusual spontaneous upper limb movements, called "Lazarus' sign", should be appreciated by examiners. This complex spinal movements need not exclude brain death. Brainstem functions such as reactivity of pupils, corneal reflex, ocular motility, pharyngeal reflex and cough reflex should be totally absent for the diagnosis. The isoelectric EEG is a predictor of brain death, if the technical requirements are carefully followed. But according to our experiences, brain-dead patients may have several waves on BAEP recordings even after obtaining a flat EEG. Because of this, BAEP examination and absence of the cerebral circulation were included in our criteria for brain death.

Brain Death↗

PubMed1989

[Auditory brainstem response in dead on arrival cases].

The relationship between ABR on the one hand and acid-base balance, EEG findings and prognosis on the other was studied in 47 cases of DOA. As for the acid-base balance, the balance tipped to acidosis in almost all cases. The ABR showed wave I to wave V in 25 cases, wave I to wave III in 2 cases and only wave I or no response in 20 cases on the admission day. The EEG was isoelectric in 27 out of 35 cases. All the patients who showed some activity in EEG had ABR which showed waves I through V. However, 11 of the 27 patients who were isoelectric EEG showed wave I through V potentials in ABR. By the relationship between EEG and ABR, the cases could be classified into 4 types, namely, 1) there are EEG activities with ABR showing up to wave V and the other types EEG are isoelectric with ABR findings that 2) wave V appears, 3) wave V disappears to leave wave I-III and 4) only I wave or becomes no response. The acid-base balance of the cases was inclined to acidosis; therefore, the effect of acidosis on ABR, EEG and disturbance of the brain tissue due to anoxic state wave suspected. Prognosis of DOA cases was poor and 87.2% died. All the patients who exhibited no response in ABR and isoelectric EEG at anytime of their course, died eventually. These findings suggest that combination of EEG and ABR enables one to learn more exactly the central function in those with disturbance of consciousness.

Acid-Base Equilibrium↗

PubMed1984

Experimental contribution to the origin of brain-stem potentials.

The origin of the different BSP waves is open to discussion. In this work we analyze the response curves with surface and intranuclear electrodes in cats, both before and after inducing electrolytic lesions in acute and chronic phase, in order to study the subsequent alterations. We found that waves whose origins are attributed to specific regions of the acoustic pathway when carried out with surface electrodes, fail to correspond with the results obtained by intranuclear electrodes. On the other hand, although the lesions to the lowest part of the acoustic pathway (cochlear nuclei) cause important alterations in the recordings, these alterations become smaller as the lesions are induced higher up the pathway. Thus, we believe that the origin of the different BSP waves is due to the sum of potentials of different zones of neuron activation, and not to specific locations of the acoustic pathway; this is more evident in the delayed waves.

Animals↗

PubMed1981

The distribution in the cat brain stem of neurones activated by vagal nonmyelinated fibres from the heart and lungs.

In anaesthetized cats, right cardiac vagal branches were electrically stimulated and recordings of evoked 'slow wave' and single neurone activity were made in the brain stem. Short-latency 'slow wave' and multi-neuronal activity evoked by excitation of myelinated vagal afferent fibres were recorded in the medial and lateral subnuclei of the nucleus tractus solitarius, the area postrema, the dorsal vagal motor nucleus, the lateral reticular formation and the nucleus ambiguus. Long-latency responses evoked by vagal non-myelinated fibres were recorded in the medial subnucleus of the nucleus tractus solitarius, the area postrema, dorsal vagal motor nucleus, the parahypoglossal area and the lateral reticular formation dorsal to the nucleus ambiguus. A specific study was made of seventy-two single neurones activated by non-myelinated afferent fibres in the cardiac branch. Thirty-four were shown to be synaptically activated, twenty-one were activated nonsynaptically and seventeen could not be classified. One neurone was also activated by myelinated cardiac afferent fibres, and two by thoracic vagal (including pulmonary) afferent fibres. Neurones were not spontaneously active. Indirect evidence suggests that the majority of the recordings of nonsynaptically activated neurones were likely to be from cell bodies. Neurones were located from the level of the obex to 3.0 mm rostral to it in the medial subnucleus of the nucleus tractus solitarius (45), and in the lateral subnucleus (2), the area postrema and its border with the medial subnucleus of the nucleus tractus solitarius (13), the dorsal vagal motor nucleus (9), the parahypoglossal area (1) and the lateral reticular formation dorsal to nucleus ambiguus (2). Recordings were made from fifteen neurones activated by myelinated fibres in the cardiac vagal branches, and twelve were excited synaptically. The neurones were located in the medial (8) and lateral (3) subnuclei of the nucleus tractus solitarius, the dorsal vagal motor nucleus (1) and the lateral reticular formation (1). Four neurones were also excited by vagal afferent fibres in the thoracic vagal nerve immediately caudal to the caudal cardiac branch.

Animals↗

PubMed2006

Electrical brain imaging reveals spatio-temporal dynamics of timbre perception in humans.

Timbre is a major attribute of sound perception and a key feature for the identification of sound quality. Here, we present event-related brain potentials (ERPs) obtained from sixteen healthy individuals while they discriminated complex instrumental tones (piano, trumpet, and violin) or simple sine wave tones that lack the principal features of timbre. Data analysis yielded enhanced N1 and P2 responses to instrumental tones relative to sine wave tones. Furthermore, we applied an electrical brain imaging approach using low-resolution electromagnetic tomography (LORETA) to estimate the neural sources of N1/P2 responses. Separate significance tests of instrumental vs. sine wave tones for N1 and P2 revealed distinct regions as principally governing timbre perception. In an initial stage (N1), timbre perception recruits left and right (peri-)auditory fields with an activity maximum over the right posterior Sylvian fissure (SF) and the posterior cingulate (PCC) territory. In the subsequent stage (P2), we uncovered enhanced activity in the vicinity of the entire cingulate gyrus. The involvement of extra-auditory areas in timbre perception may imply the presence of a highly associative processing level which might be generally related to musical sensations and integrates widespread medial areas of the human cortex. In summary, our results demonstrate spatio-temporally distinct stages in timbre perception which not only involve bilateral parts of the peri-auditory cortex but also medially situated regions of the human brain associated with emotional and auditory imagery functions.

Acoustic Stimulation↗

PubMed2003

Finite-element simulation of cooling of realistic 3-D human head and neck.

Rapid cooling of the brain in the first minutes following the onset of cerebral ischemia is a potentially attractive preservation method. This computer modeling study was undertaken to examine brain-cooling profiles in response to various external cooling methods and protocols, in order to guide the development of cooling devices suitable for deployment on emergency medical vehicles. The criterion of successful cooling is taken to be the attainment of a 33 degrees C average brain temperature within 30 min of treatment. The transient cooling of an anatomically correct realistic 3-D head and neck with realistically varying local tissue properties was numerically simulated using the finite-element method (FEM). The simulations performed in this study consider ice packs applied to head and neck as well as using a head-cooling helmet. However, it was found that neither of these cooling approaches satisfies the 33 degrees C temperature within 30 min. This central conclusion of insubstantial cooling is supported by the modest enhancements reported in experimental investigations of externally applied cooling. The key problem is overcoming the protective effect of warm blood perfusion, which reaches the brain via the uncooled carotid arterial supply and effectively blocks the external cooling wave from advancing to the core of the brain. The results show that substantial cooling could be achieved in conjunction with neck cooling if the blood speed in the carotid artery is reduced from normal by a factor of 10. The results suggest that additional cooling means should be explored, such as cooling of other pertinent parts of the human anatomy.

Algorithms↗

PubMed1994

Fractionated high-dose rate brachytherapy for intracranial gliomas.

PURPOSE: To develop a catheter system for fractionated high-dose rate (HDR) brachytherapy for intracranial gliomas. METHODS AND MATERIALS: The catheter system for stereotactic placement as well as delivery of the high-dose rate iridium-192 source wire is described. The force of the impulse wave from the source wire entering brain equivalent material was measured. Dose volume histograms for the first 5 patients treated are presented. RESULTS: The catheter system was found to be satisfactory. The maximum force of the impulse wave was less than 1 acceleration of gravity (which is safe). The patients tolerated the treatment well with no significant problems related to the catheters being left in situ for up to 14 days. CONCLUSION: Based on this pilot experience a phase I dose escalating and morbidity study has been initiated.

Brachytherapy↗

PubMed2002

Homeostatic control of slow-wave and spindle frequency activity during human sleep: effect of differential sleep pressure and brain topography.

The impact of a 40 h sleep deprivation versus a 40 h multiple nap paradigm on topographic and temporal aspects of electroencephalographic (EEG) activity during the subsequent recovery sleep was investigated in 10 young volunteers in a controlled 'constant posture' protocol. The accumulation of sleep pressure with extended wakefulness could be significantly attenuated by intermittent naps. The differential sleep pressure conditions induced frequency- and topographic-specific changes in the EEG slow wave range (0.5-5 Hz) and in the low (LSFA, 12.25-13.25 Hz) and high spindle frequency activity range (HSFA, 13.75-16.5 Hz) during non-REM sleep. The observed increase of EEG slow-wave activity (SWA) after high sleep pressure was significantly more pronounced in the fronto-central (Fz, Cz) than in the parieto-occipital (Pz, Oz) derivations. Low sleep pressure after the nap paradigm decreased SWA with an occipital predominance. Spindle frequency activity showed a dissimilar homeostatic regulation: HSFA was significantly decreased after high sleep pressure and increased after low sleep pressure, exclusively in the centro-parietal brain region (Cz, Pz). LSFA was significantly enhanced after both manipulations. The data indicate that EEG activity, in particular frontal SWA and centro-parietal HSFA, are under a clear sleep-wake-dependent homeostatic control and imply a reciprocal relationship in the homeostatic regulation of SWA and HSFA, which however shows different spatio-temporal aspects.

Adult↗

PubMed1981

[Decimeter wave therapy in the rehabilitation of stroke patients].

A new approach to the treatment of cerebral strokes is discussed. This approach consists in exposing the pathological focus in the brain to the action of decimeter electromagnetic waves (DW). The results of treating 112 patients with cerebral circulation disorders have demonstrated a sufficiently high effectiveness and a broad range of the therapeutic action of this new method. The decimeter waves contributed to restoration of the motor and sensor functions in the patients with the cerebral strokes; they produced a regulatory effect on the cerebral ad peripheral blood circulation, the brain bioelectric activity, the functions of the neuromuscular apparatus, lipid metabolism, the blood coagulation and anticoagulation system and the neuromediator metabolism. The data obtained suggest that it is a diminution (achieved with the use of DW) of the pathological impulsation flow from the pathological focus in the brain that plays the main role in the restoration of the impaired functions in patients with cerebral strokes. This conclusion is very important for understanding the pathogenesis of cerebral circulation disturbances.

Adult↗

PubMed1995

[The effect of aspirin on the contingent negative wave in healthy subjects].

Alterations in parameters of slow brain potentials (contingent negative variation, CNV) were examined in healthy individuals under influence of aspirin according to double blind method. The early and late waves of CNV were analysed. The significant decrease of early wave of CNV was obtained after aspirin administration. Late wave of CNV increased after aspirin and placebo intake. The alterations described were explained in terms of central mechanisms of aspirin action including noradrenergic and dopaminergic systems involvement.

Adolescent↗

PubMed1984

PO2 and pH measurements within the rabbit oviduct following tubal microsurgery: reanastomosis of previously dissected tubes.

Adhesions of the fallopian tube might be a source of generalized infertility. In order to improve the mechanical and functional properties of the oviduct, microsurgical replacement of the affected tubular segments have been applied, however, with contradictory results. In order to improve the situation and gain further information about this problem, catheter microelectrodes for Po2 and pH measurements within the lumen of the fallopian tube have been developed. The validity of the measurements was tested in a series of rabbits (Dutch belt strain, n = 19, 3.5-4.5 kg bw) which have been laparatomized under pentobarbital anesthesia during the oestrus phase. From one side of the oviduct 1 cm was resected and the free ends reanastomosed while the other side served as a control. Six to eight weeks later Po2 and pH values within the oviduct were measured. After another 4-5 weeks ovulation had been induced and artificial insemination performed. 64 hours later the rabbits were sacrificed. The oviducts were isolated and the corpora lutea as well as the ova were collected and examined histologically. The mean Po2 of the oviduct was 53 (+/- 16) mm Hg (mean +/- SD) for the control side and 56 (+/- 13) mm Hg (mean +/- SD) within the anastomosed tubes. The range of values was the same in both groups (n = 8) 34-75 mm Hg. A T-test comparison of the means of the two groups gave p-values which were not significant (p greater than 0.1). Po2 fluctuations with small-fast amplitudes (1 mm Hg) and additional slow-large oscillations (about 20 mm Hg) have been observed similar to the Po2 waves described for muscle and brain. The mean pH value of the oviduct a showed slight, statistically significant pH differences (7.75 reanastomosed side, 7.94 control side) whereby the degree of adhesions was correlated with luminal pH value. In three rabbits the relationship between corpora lutea and fertilized ova was 1:6, 2:9, 3:6 for the reanastomosed side while the control side showed balanced quotients of 4:4, 4:4, 6:6. In two rabbits unfertilized ova have been observed within the reanastomosed tubes where the typical outside layer of mucoproteids was absent while the control side was normal. Nevertheless, within both oviducts a continuous layer of epithelial cells has been observed even after reanastomosis.

Animals↗

PubMed2004

[Alzheimer's disease with secondary Parkinson's syndrome. Case report of a patient with dementia and Parkinson's syndrome after long-term occupational exposure to insecticides, herbicides, and pesticides].

This case report describes long-term occupational exposure to agricultural insecticides, herbicides, and pesticides as possible environmental risk factors of Alzheimer's disease (AD) and Parkinson's syndrome in a 59-year-old man. Initially the patient complained about disturbances in concentration, mnestic deficits, and problems finding words. In the further course of the disease, he developed Parkinson's syndrome with predominant hypokinesia and rigor in addition to mild-to-moderate dementia. Low levels of beta-amyloid 1-42 were found in the CSF. Electroencephalography showed left frontotemporal theta waves. Cranial MRI revealed general brain atrophy with a maximum biparietally. In cerebral positron emission tomography, general hypometabolism was found with maxima biparietally and left frontally. The possible differential diagnosis of AD and Parkinson's syndrome is discussed.

Agricultural Workers' Diseases↗

PubMed1979

Permeability of the blood-brain barrier to mannitol in the rat following 2450 MHz microwave irradiation.

The radiotracer method of Oldendorf was used to determine if 2450 MHz continuous wave (CW) microwave energy increases blood-brain barrier permeability to [14C]mannitol, which is normally excluded from entering the brain. Anesthetized, adult rats were irradiated singly for 30 min in the quiet zone of an anechoic chamber, at average power densities from 0.1 to 30 mW/sq.cm. Afterwards each rat received an intracarotid bolus injection of [14C]mannitol/[3H]water mixture and was decapitated 15 sec later. Uptake of [14C]mannitol relative to the highly permeable reference substance, [3H]water, was calculated as the brain uptake index (BUI) for 4 brain regions. Mean BUI values for tissues from the microwave-irradiated rats did not differ significantly from sham-irradiated animals, and a microwave influence on barrier permeability was not evident. Irrespective of treatment, BUI values for cerebellum and medulla were much higher and more variable than values for cortex or diencephalon, and were associated with reduced absorbance or retention of [3H]water. Because of a compromising influence of the vertebral arterial supply on the distribution of intracarotid-injected radiotracers, BUI measurements in caudal brain regions are probably unreliable unless accompanied by data on regional radioisotope concentrations. The absence of such data in an earlier BUI study, suggests that increases in BUI for cerebellum and medulla attributed to microwaves were possibly misinterpreted as differences in barrier permeability to [14C]saccharides, when in fact changes in blood flow and [3H]water influx or egress were responsible.

Animals↗

PubMed1983

The effects of hypoxia and CO2 on the sleep-waking pattern of the potoroo (Potorous tridactylus apicalis).

Four male potoroos (Potorous tridactylus apicalis) breathed 21% and 7% O2 with and without the addition of 5% CO2. The effects of these gas mixtures on the potoroo's sleeping-waking pattern (SWP) were studied. The SWP while breathing 21% O2/5% CO2 was unchanged when compared with that of breathing ambient air (21% O2). While breathing 7% O2, the SWP was severely disrupted: total sleep time (TST) and slow wave sleep (SWS) increased markedly. Brain temperature fell substantially. Paradoxical sleep (PS) was almost abolished and wakefulness (W) decreased. The addition of 5% CO2 to the O2 deficient gas mixture, i.e., 7% O2/5% CO2, restored the SWP to that obtained while breathing ambient air. It is concluded that CO2 neutralizes the disruptive effect which hypoxia has on the potoroo's SWP. It is hypothesized that this constitutes a homeostatic mechanism for stabilizing the SWP and is carried over from pouch life.

Animals↗

PubMed1994

Equivalent dipole parameter estimation using simulated annealing.

Equivalent-electrical dipole source modeling of evoked potential signals requires complicated non-linear multivariate optimization. Newton and non-linear simplex optimization methods often converge to a local minimum, and their results are affected by the procedure's starting parameter estimates. This paper describes simulated annealing, a more robust and resistant global optimization method. As an illustrative example, both the simplex and simulated annealing algorithms were used for parameter estimation in modeling wave V of the brain-stem auditory evoked potential (BAEP) using a single decaying sinusoid dipole source. Data for a single subject from 3000 responses to stimuli on each of 2 days were recorded, with modeling performed on 1000 response subaverages. Each estimation problem was run with 5 different sets of starting parameters. Simulated annealing always converged to the global minimum regardless of the starting parameter estimates while simplex often converged to markedly different solutions for different starting parameter estimates. No association was apparent between the simplex's converging to a local minimum and the closeness of the starting estimates to the true parameter values. Implementation of simulated annealing is discussed in terms of cooling schedules and other procedure parameters.

Acoustic Stimulation↗