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Biomedical subjects

W Burr

Publications and source records attributed to W Burr.

At least 19 recordsLinked to original sources
PubMed1998

Seizure occurrence during ovulatory and anovulatory cycles in patients with temporal lobe epilepsy: a prospective study.

We investigated the influence of ovulatory and anovulatory menstrual cycles on seizure occurrence in female patients with complex partial seizures. We prospectively documented seizures in relation to menstrual cycles (defined by measurement of basal body temperature and progesterone serum concentrations) in 39 female patients. One hundred and thirty-two cycles of 35 patients entered final analysis. Only eight patients had anovulatory cycles, in 18 patients all cycles were ovulatory. In the remaining nine patients anovulatory as well as ovulatory cycles were documented. In ovulatory cycles the mean frequency of seizures during the days of menstruation was significantly higher as compared to the periovulatory or the luteal phase of the cycles. During anovulatory cycles seizure frequency was significantly lower during menstruation than in the remaining days of the cycles. Since progesterone is known to exhibit anticonvulsant effects, seizure occurrence during menstruation seems to be related to ovulatory cycles, possibly due to the premenstrual decrease of progesterone. Therapeutic recommendations for the treatment of seizures related to the menstrual cycle (catamenial seizures) include the administration of hormones, as progesterone (recommended especially for women with catamenial epilepsy who have a documented inadequate luteal phase) or the suppression of the menstrual hormonal cycle by synthetic gonadotropin releasing hormone analogs.

Journal Article↗
PubMed1997

Possibilities and limitations of magnetic source imaging of methohexital-induced epileptiform patterns in temporal lobe epilepsy patients.

The usefulness of MEG-based techniques in lateralizing and localizing the epileptogenic area was investigated in the present study. Spontaneous and methohexital-induced spikes were studied in a group of 15 patients with temporomesial epilepsy using a 37-channel neuromagnetometer. The accuracy of the magnetic source imaging was compared to the results of electrocorticographic (ECoG) recordings. Differences of drug-induced spike densities in the MEG recordings between both sides confirmed a similar lateralizing power of the MEG and ECoG recordings. Source location analyses based on a moving dipole model resp. a rotating dipole model were performed using a spherical head model. After subdivision of the volume of each patient's head, 8 cm3 cubicles containing at least 3 source locations were projected onto the individual MRI scan and resulted in source locations within or close to the presurgically defined primary epileptogenic area only in 3 of the 15 patients. Spike induction by methohexital has the advantage of shortening the recording period as compared to recordings of interictal epileptiform discharges. However, the correlation analyses of spike densities from MEG and ECoG recordings and the source location analyses from MEG recordings indicate that spike generated in deep temporomesial structures may escape the MEG registration.

Adolescent↗
PubMed1994

Subdural electrodes.

Physical aspects favour subdural registrations: as the solid angle under which a source is seen from a nearby electrode, the potential is large; there is no distortion by high impedence between source and electrode, nor by perpendicular short circuits; the frequency response is quasi-linear. Technical aspects and implantation strategy are outlined. Interictal and ictal ECoG patterns of diagnostical relevance and activation procedures are discussed. Advantages of subdural electrodes are: They provide detailed information on the epileptogenic zone, data on prognosis, are free of artefacts, allow electrical stimulation to determine eloquent cortex areas; by mathematical analysis methods the localizing power is increased. Disadvantages are: closed fields can be missed (recordable only by depth electrodes), in comparison to EEG, costs are considerably higher. Risks are practically absent with strip electrodes. In about half of the investigated patients, subdural electrodes were necessary to minimize the area of resection on a rational basis.

Brain↗
PubMed1992

Serum prolactin concentrations and epilepsy. A study which compares healthy subjects with a group of patients in presurgical evaluation and circadian variations with those related to seizures.

In 20 healthy subjects (10 female and 10 male) and 17 patients undergoing presurgical epilepsy evaluation with intracranial EEG electrodes, circadian variations of serum prolactin (PRL) were measured. A comparison between the peak values found in normals with the postictal rises in patients, led us to consider 700 microU/ml to be the threshold of diagnostic value and the observed rises above this level to be all induced by seizures. In order to assess the clinical value of this threshold, PRL was measured postictally in a further 30 patients with epilepsy and in 11 patients with psychogenic seizures. In none of the latter group did PRL rises exceed 700 microU/ml, while they did so in 39% of the complex partial seizures and in 80% of the tonic-clonic seizures. There was no significant difference with respect to sex (a rise over 700 microU/ml in 42% in male and in 55% in female patients). Based on the findings in 17 patients investigated by means of intracranial electrodes, we were not able to establish different criteria for different focus localisations: in 66% of both temporal as well as frontal lobe seizures the 700 microU/ml level was exceeded. As a trend, in the period preceding an epileptic seizure we found a slightly decreasing PRL level, whereas in healthy persons the PRL concentrations gradually increased in the 40 minutes before the maximum spontaneous peak was reached.

Adolescent↗
PubMed1992

[A brief psychotherapeutic synergistic approach in child and adolescent psychiatry].

The controversy between the concepts of family therapy and systemic therapy is one issue to design a synergetic concept of brief therapy in the psychiatric treatment of children and adolescents. Some principles of the radical-constructivism, systemic theory an the psychology of narratives will be discussed and related to concepts of solution-oriented brief therapy. A case example demonstrates the perspectives of this approach in the ambulant psychiatric treatment.

Adolescent↗
PubMed1991

Current status of whole-body counting as a means to detect and quantify previous exposures to radioactive materials. Whole-body Counting Working Group.

This report discusses the principles, techniques, and application of whole-body counting with respect to previous radiation exposure. Whole-body counting facilities are located nationwide and have a wide range of capabilities. A listing of these facilities is provided in Appendix A. However, only a few facilities are truly state-of-the-art and have the sophisticated capabilities required to attempt detection of low-level activity in vivo. Measurements made many years after exposure can be extremely difficult to interpret. The precision and accuracy of resulting dose estimates are functions of such factors as the assumptions made concerning intake, time since intake, radionuclide metabolism, and level of intake. The indiscriminate application of metabolic models to current body contents or minimum detectable amounts of radionuclides with relatively short effective half-lives (such as 137Cs) can lead to absurd results when used as a basis for calculating intakes 25 and 40 y ago. Skull counting for 90Sr-90Y and 239,240Pu can set upper limits on possible uptakes and radiation doses, but in the case of 239,240Pu, the limits are rather high. In both cases, the accuracy of the limits depends on the metabolic models used in the calculations. These models (ICRP 1979) were developed to set safety standards for the intakes of radionuclides by workers and are not intended to be used to back-calculate uptakes and radiation doses from measurements made long after the uptake. There are, therefore, large uncertainties in any conclusions derived from these calculations. The experience gained over the years with whole- and partial-body counting has consistently shown that they are of little use in determining body contents of radionuclides resulting from exposure to weapons debris decades earlier. The development of new detectors such as an array of lithium-drifted silicon devices offers some hope of lowering the minimum detectable amount (MDA) for Pu and Am, but such detectors are still several years from routine application and do not represent current state-of-the-art. Furthermore, it is doubtful that such improvements will be sufficient to meet the need of assessing radiation exposures that occurred decades earlier.

Accidents↗
PubMed1991

Current status of biological indicators to detect and quantify previous exposures to radiation. Biological Indicators Working Group.

Hematologic changes following whole-body exposure to gamma or x-ray radiation have been used to estimate dose. The usefulness of this biological indicator is limited because of the recovery of these cells with time, thus making it unsuitable for estimation of dose years after exposure. The same is true for spermatogenic indicators; recovery and restoration of sperm numbers and fertility makes this biological indicator impractical for assessing radiation dose decades after radiation exposure. As noted in the text of the report, immunological concepts are in a state of rapid development, and it is possible that improved methods for applying immunologic procedures as biological indicators of radiation may be developed in the future. However, at the time, immunological indicators are not useful, even in an early time period, for quantitating radiation dose after total-body irradiation. A semiquantitative effect is observable in the early phase after total-body irradiation over a period of days to weeks, but there is little data available to indicate whether any of the immunological parameters can be indicative of a dose when the test is applied several years after radiation exposure. More detailed information regarding immunological indicators for estimating irradiation dose has been summarized elsewhere (Wasserman 1986). There is good agreement that ionizing radiation causes biochemical changes in the body; however, attempts to apply these changes to provide a reliable biological dosimetry system have not been particularly successful. The status of this research has been summarized by Gerber (1986). One of the difficulties has been the problem of establishing clear dose-effect relationships in humans. The lack of specificity in the response for radiation is another problem. Additional problems are due to the strict time dependency of biochemical changes and the limited duration of the changes during the postexposure period. Information on biochemical indicators is based on animal experiments; human experience is limited to a relatively few accidental human exposures and investigations involving patients undergoing radiation therapy. It appears that none of the biochemical indicators studied are currently useful for radiation dosimetry. Even if further developed, it is questionable whether or not biochemical indicators could be of use in estimating radiation dose received years and decades prior to the assay.

Blood↗
PubMed1991

Current status of bioassay procedures to detect and quantify previous exposures to radioactive materials. Bioassay Procedures Working Group.

This report was prepared by a working group established by the Oak Ridge Associated Universities (ORAU) for the purpose of assessing the current capabilities of bioassay methods that can be used to determine the occurrence and magnitude of a previous internal deposition of one or more radionuclides. The first five sections discuss general features of the use of in-vitro bioassay samples to achieve this purpose. The remainder of the report is focused on the possible use of urine bioassay procedures to detect and quantify internal depositions of radionuclides that may have occurred in United States occupation troops in Hiroshima or Nagasaki, Japan, prior to 1 July 1946, or to personnel who participated in atmospheric nuclear weapons tests conducted between 1945 and 1962. Theoretical calculations were made to estimate the quantities of various radionuclides produced in a 20-kiloton (kt) nuclear detonation that might still be present in measurable quantities in people today if they were exposed 25 to 40 y ago. Two radionuclides that emerged as good choices for this type of bioassay analysis were 90Sr, which emits beta particles, and 239,240Pu, which emits alpha particles. The current status and future prospects of chemical procedures for analyzing in-vitro urine bioassay samples for these two radionuclides were examined to determine the minimum amounts that could be detected with current methods and how much one might expect the sensitivity of detection to improve in the near future. Most routine 239,240Pu bioassay analyses involve detection by alpha spectrometry. The current minimum detectable amount (MDA) is about 0.74 mBq L-1 (20 fCi L-1), but this could be lowered to 74 muBq L-1 (2 fCi L-1). An MDA of 0.74 mBq L-1 (20 fCi L-1) is adequate for routine bioassay analyses but is too high to detect most uptakes of 239,240Pu that may have occurred 25 to 40 y ago. Methods under development that are or can be much more sensitive and have lower MDAs than alpha spectrometry for 239Pu are fission track analysis and mass spectrometry. Currently, the fission track analysis method has an MDA of about 19 muBq L-1), and this may eventually be lowered to 1.9 muBq L-1 (0.005 fCi L-1). The current MDA for 239Pu by mass spectrometry is about 7.4 mBq L-1 (200 fCi L-1), but the potential exists that it could be lowered to a value of about 0.37 muBq L-1 (0.01 fCi L-1).(ABSTRACT TRUNCATED AT 400 WORDS)

Feces↗
PubMed1988

Double-blind placebo-controlled trial with flunarizine in therapy-resistant epileptic patients.

The anticonvulsant efficacy and side-effect liability of flunarizine (15 mg/day) was investigated in a randomized, double-blind, placebo-controlled, crossover design in 30 outpatients with drug-resistant complex partial seizures. Flunarizine or placebo was added to the preexisting medication and each patient was followed up for 10 months. At the end of the study data from 22 patients were available for evaluation. In patients taking first flunarizine and then placebo, plasma levels of flunarizine were still detectable at the end of the 4 months' placebo phase. In the group of 13 patients starting therapy with placebo, a significant seizure frequency reduction was observed during the flunarizine period in 11 patients, whereas one patient showed no change and seizure frequency increased in another patient. Two patients had a 50% reduction in seizure frequency. Flunarizine was well tolerated and few side effects were noted.

Adolescent↗
PubMed1987

Functional and morphological abnormalities in temporal lobe epilepsy: a comparison of interictal and ictal EEG, CT, MRI, SPECT and PET.

Ten patients suffering from drug-resistant complex partial seizures, with EEG abnormalities in the temporal region, were studied by means of non-invasive electrophysiological techniques (video-monitored, 16-channel, prolonged surface and sphenoidal EEG) as well as by imaging techniques (CT, MRI, SPECT and PET). Analysis of interictal and ictal EEG indicated the localization of epileptic activity in one side in eight cases. CT demonstrated focal abnormalities in three, SPECT in five unequivocally (in another four questionably, with the same lateralization as indicated by PET), MRI in eight, and PET in all cases. While only EEG provided specific diagnostic information, the focus definition was consistently good on PET images, poor on CT scans, and generally good but less consistent on MRI.

Adult↗
PubMed1987

Day by day variations of the amount of spike-wave activity in 24 hour cassette recordings.

For interpretation of mobile long-term EEG monitoring in patients suffering from absence epilepsies with regular spike-wave (S-W) paroxysms, the fluctuating amount of this parameter has to be taken into account if, for example, therapeutic effects are to be judged. An 'S-W variogram' is derived resembling the statistical properties of the day by day variability as an orienting criterion in this respect.

Circadian Rhythm↗
PubMed1986

Computerized analysis of epileptic activity and sleep in mobile long-term EEG monitoring.

Implemented on a LSI 11/73 microcomputer, an approach is presented to perform pattern recognition of one channel in high speed (factor 20). A mimetic algorithm, acting in time domain, continuously tests the signal with respect to the occurrence of spike-wave-like patterns and calculates a low frequency index describing the time of sleep. Those epochs suspected of containing paroxysmal activity are stored on disk for subsequent editing. In a similar way, 8-channel analysis is possible if the replay speed is less than 20 times real time.

Ambulatory Care↗
PubMed1986

Epileptic activity during sleep and wakefulness.

In 23 untreated patients the temporal distribution of generalized spike-wave activity was investigated by means of mobile long-term EEG recordings. Distribution classes (S, A, W) were defined if the relative amount of epileptic activity within the phases sleep, awakening and waking exceeded a threshold, otherwise a diffuse distribution (D) was scored. A, S and D distributions were found approximately with the same frequency. In no patient was the middle part of the night most prominent. In one patient, it was shown by micro-hypnograms that 'micro-arousals' are closely related to spike-wave activity.

Adolescent↗
PubMed1986

Prescribing in pregnancy. Thyroid disease.

When treating thyroid disease, as with other conditions in pregnancy, one is concerned with the welfare of both mother and developing child. Thyroid disease causes few maternal problems; thyrotoxicosis in fact tends to improve in pregnancy, allowing medical management with lower drug doses than usual. Relapse of thyroid disease may occur postpartum, when transient hypo- and hyperthyroidism are relatively common. In contrast, the fetus and neonate are threatened in a number of ways by drugs given to the mother and by transplacental passage of maternal antibodies capable of inducing thyroid disease. Antithyroid drugs may cause fetal goitre with airway obstruction, and are associated with mild neonatal hypothyroidism. Thyroid antibodies in primary myxoedema and Hashimoto's thyroiditis are occasionally implicated in neonatal hypothyroidism and may even cause thyroid dysgenesis. Neonatal hyperthyroidism has a high morbidity and mortality and may have long-term skeletal effects such as craniosynostosis. Fetal problems may not be apparent at birth but may emerge in the next eight to ten days, especially in hyperthyroidism when the mother has been on treatment. Close monitoring throughout pregnancy and for the first ten days postpartum is required to minimize risks to the fetus and neonate. Most pregnancies associated with thyroid disease will have a successful outcome. If the occasional at-risk fetus is to be identified and treated successfully there should ideally be close cooperation between obstetrician, endocrinologist and paediatrician.

Antithyroid Agents↗