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Biomedical subjects

N So

Publications and source records attributed to N So.

12 recordsLinked to original sources
PubMed1990

Quantitative EEG analysis of carbamazepine effects on amygdaloid kindled seizures in cats.

We studied the effects of carbamazepine (CBZ) on seizure behaviour and electroencephalographic (EEG) activity in 6 amygdala kindled cats. CBZ reduced the behavioural severity of kindled seizures and prolonged the earlier seizure stages (latency to stage 4). These effects were not always paralleled by a reduction in the duration of seizure activity. EEG activity paradoxically increased in amplitude during early and mid-seizure, then fell in late seizure after CBZ. CBZ also caused an overall decrease in EEG coherence during mid and late seizure. These observations represent a first attempt to use quantitative EEG analysis to investigate the effects of anticonvulsants on electrographic seizure activity. The duration of postictal EEG suppression was reduced after CBZ treatment. The results support the view that CBZ has a major effect on limiting the spread of seizure discharges.

Administration, Oral↗
PubMed1990

Immunocytochemical characterization of supporting cells in the enteric nervous system in Hirschsprung's disease.

The enteric nervous system (ENS) is composed of two distinct neural components, extrinsic and intrinsic, and its supporting cells uniquely possess some characteristics of both central nervous system (CNS) astrocytes and peripheral nervous system (PNS) Schwann cells. To provide further insight into the neural defects in Hirschsprung's disease, the supporting cells in biopsied normal gut, ganglionic, and aganglionic segments from six cases of Hirschsprung's disease were investigated immunocytochemically for localization of three neuroglial markers, glial fibrillary acidic protein (GFAP), S-100 protein, and glutamine synthetase (GS), by the avidin-biotin-horseradish peroxidase complex method applied to free-floating thick cryostat sections. In normal control gut and ganglionic segments of Hirschsprung's colon, all of the GFAP, S-100, and GS were expressed strongly by the supporting cells of the myenteric and submucosal plexuses, interconnecting nerve fiber bundles of the plexuses, and fine nerve strands in the muscular layer. The nerve bundles of the subserosa merging into the muscular layer were also immunoreactive for GFAP and S-100, but negative or only faintly positive for GS. On the other hand, aberrantly proliferated nerve bundles in the aganglionic segment of the Hirschsprung's colon were accompanied by supporting cells strongly positive for GFAP and S-100, but negative or faintly positive for GS. These results indicate that the supporting cells of the enteric neurons proper, enteric glia, express GFAP, S-100, and GS, whereas the supporting cells of the extrinsic components, which accompany PNS axons, are negative or very weakly positive for GS. Thus, GS immunocytochemistry may delineate intrinsic and extrinsic neural components in the ENS, and may provide an important clue for differential diagnosis of Hirschsprung's disease.

Biopsy↗
PubMed1990

Human adenoidal organ culture: a model to study nontypable Haemophilus influenzae (NTHI) and other bacterial interactions with nasopharyngeal mucosa--implications in otitis media.

Nontypable Haemophilus influenzae (NTHI) has become the predominant cause of both acute suppurative otitis media and chronic otitis media with effusion. It has now been well-demonstrated that both outer membrane proteins and restriction fragment analysis of the bacterial genomes of concomitant nasopharyngeal and middle ear effusion isolates of NTHI are identical. It is therefore of critical importance to understand the mechanisms whereby bacteria that are present in normal healthy children in small numbers become the predominant organism in the nasopharynx in otitis media. The studies presented here suggest that nontypable Haemophilus influenzae can effectively decrease ciliary function as measured by stroboscopic illumination of ciliary beat frequency on human adenoidal organ culture. This organism also produces significant histopathologic and ultrastructural damage to the epithelial cells and cilia of adenoid organ culture, demonstrated by both light microscopy and scanning electron microscopy. The data suggest the following hypothesis: nontypable Haemophilus influenzae can destroy mucociliary function and allow increased bacterial replication in the mucus overlying the nasopharyngeal mucosa. The mucociliary system of the eustachian tube may also be involved in a similar manner, thus allowing bacteria to enter the middle ear space via the eustachian tube.

Adenoids↗
PubMed1990

Changes in seizure activity following anticonvulsant drug withdrawal.

We retrospectively studied the effects of changing antiepileptic drug levels on patterns of seizure discharge in 8 patients investigated with intracerebral electrodes during presurgical evaluation. We compared seizures recorded at high levels of medication to seizures recorded at low levels for changes in seizure duration, duration from unilateral onset to contralateral spread, inter- and intrahemispheric coherence, and morphology of EEG discharges. Seizures were more frequent with low medication, as was secondary generalization. Reduction in medication did not affect the morphology of discharges at onset, duration to contralateral spread, and coherence between EEG discharges. Seizures of similar type (eg, complex partial seizures without secondary generalization) were not longer with low than with high medication. Whereas medication clearly affects seizure frequency and generalization, it has little effect on the pattern of early parts of seizures. In particular, we found no evidence that seizure discharges become bilateral or generalized more quickly when medication is reduced.

Anticonvulsants↗
PubMed1989

Depth electrode investigations in patients with bitemporal epileptiform abnormalities.

Fifty-seven patients showing bitemporal independent epileptiform abnormalities on extracranial electroencephalograms (EEGs) in whom the epileptogenic zone could not be localized or lateralized by extracranial EEG and other noninvasive tests were investigated with stereotactic depth electrode recordings. In a majority of 44 patients (77%), seizures originated exclusively or with a strong predominance in one temporal lobe only. Of the remaining 13 patients (23%), 8 had seizures originating independently in either temporal lobe without significant lateralized predominance, and 5 had multiple seizure patterns, which were often diffuse. The patterns of seizure onset as recorded by depth electrodes tended to vary even in the same patient. Electrical stimulation studies and the determination of afterdischarge thresholds were of limited utility for lateralization of seizure onset.

Adolescent↗
PubMed1989

Results of surgical treatment in patients with bitemporal epileptiform abnormalities.

Fifty-three of 57 patients who had evidence of bitemporal epileptiform abnormalities and who required investigation with stereotactic depth electroencephalography (SDEEG) recordings to determine the site of origin of seizures underwent surgical resection for the treatment of their epilepsy. A minimum of 2 years' follow-up was available in 48 patients who underwent a temporal lobe resection. In this group, 19 patients (40%) were greatly improved, and of these 14 (29%) became seizure free and 5 (10%) had no more than 3 seizures each year. Another 22 patients (46%) showed a worthwhile reduction in seizure frequency of at least 50%. Seven patients (15%) were not significantly improved. An etiological factor of early convulsions before age 3 (usually febrile) was associated with a better outcome. Both the lack of a strong predominance for SDEEG-recorded seizures to arise in the resected temporal lobe and the presence of residual epileptiform abnormalities in the postexcision electrocorticogram were correlated with poorer results.

Adult↗
PubMed1989

Myoclonus epilepsy and ragged-red fibres (MERRF). 2. Electrophysiological studies and comparison with other progressive myoclonus epilepsies.

Electrophysiological studies (EEG, evoked potentials, nerve conduction and EMG) in 13 patients with myoclonus epilepsy with ragged red fibres (MERRF) are presented. The most notable findings are the presence of atypical irregular generalized spike and wave discharges arising from an abnormal EEG background (9 patients), focal epileptiform abnormalities (6 patients) most commonly over the occipital regions and giant cortical SEPs (4 of 6 patients tested). Similar findings of disturbed EEG background activity, generalized spike and wave discharges and giant cortical SEPs appear to be shared by the group of diseases characterized by progressive myoclonus epilepsy.

Adolescent↗
PubMed1985

Determination of serum methotrexate and 7-hydroxymethotrexate concentrations. Method evaluation showing advantages of high-performance liquid chromatography.

The use of large doses of methotrexate (MTX), greater than 3 g/m2, for the treatment of some malignant disorders requires careful monitoring of serum concentrations. A simple and sensitive method for the separation of MTX and 7-hydroxymethotrexate (7-OH-MTX) by reversed-phase high-performance liquid chromatography (HPLC) is described. The method involves deproteinizing the serum sample on a Sep-Pak C18 cartridge, followed by separation on a C18 column and detection at 313 nm. The extraction efficiency of free MTX from serum is 70% and the maximum sensitivity is 2.2 X 10(-8) M. A high degree of correlation was obtained between the HPLC method of serum MTX determination and an enzyme multiplied immunoassay technique. The HPLC method separates MTX from its analogues, or drugs which may be administered concomitantly with MTX. Concentrations of MTX and 7-OH-MTX achieved over a 24-h period during high-dose therapy, (500-1000 mg/m2), and over 48 h for very-high-dose methotrexate therapy (8-12 g/m2) are described. A significant observation is the presence of 7-OH-MTX in sera of patients 6 h after commencement of infusion. This method was also utilized for monitoring cerebrospinal fluid MTX concentrations.

Chromatography, High Pressure Liquid↗