Neurometabolic effects of ACTH on free amino compounds in opsoclonus-myoclonus syndrome.

To evaluate the possible role of central free amino compounds in pediatric opsoclonus-myoclonus syndrome (OMS), 21 cerebrospinal fluid (CSF) amino compounds were measured by an amino acid analyzer or mass spectroscopy in 74 anesthetized children, 54 with OMS and 20 age-matched neurological controls. In OMS, only phosphoethanolamine was increased compared to controls; OMS severity and duration had significant converse effects on alanine and phosphoethanolamine. In contrast, corticotropin (ACTH) treatment was associated with increased alanine and phenylalanine, and decreased taurine compared to controls and untreated OMS, and increased glutamine, lysine, ornithine, and tyrosine compared to untreated OMS. Other than low taurine, these effects were not found with corticosteroid treatment, and non-steroidogenic immunotherapy had no effect. The ACTH dose-association was most apparent for alanine and phosphoethanolamine, but lysine and ornithine were also higher in the high-dose ACTH group. There were no significant disease- or treatment-associated perturbations in GABA, glycine, or other amino acids. These data suggest a unique pattern of ACTH effects on non-neurotransmitter CSF amino compounds, for the most part not shared by steroids.

The role of percutaneous umbilical blood sampling in the management of immune thrombocytopenic purpura.

On consultation, percutaneous umbilical blood sampling (PUBS) was offered to women with immune thrombocytopenic purpura (ITP) to determine the mode and site of delivery prior to labour. Between January 1989 and December 1993, 41 pregnant women underwent PUBS. All women had a history of ITP, a platelet count less than 90 K, (+) antiplatelet antibody, and/or thrombocytopenia diagnosed early in pregnancy. PUBS was performed at term except in one patient with preterm labour, who underwent PUBS at 31 weeks' gestation. Patients with fetal platelet counts greater than 50 K returned to their referring physician for delivery. Records were complete in 39 pregnancies. Fetal blood was successfully obtained in 37 of 39 cases (95 per cent). Fetal platelet counts correlated with neonatal platelet counts in 36 of 37 cases (97 per cent). The interval between PUBS and delivery ranged from 0 to 31 days. Six of 37 fetuses (16 per cent) had significant fetal thrombocytopenia (< 50 K). These six patients underwent Caesarean section. Vaginal delivery was recommended in all others. There were two procedure-related complications. There were no cases of intraventricular haemorrhage in any of the neonates. In conclusion, there is a high incidence of fetal thrombocytopenia in women with ITP. PUBS reliably detects fetal thrombocytopenia and is therefore useful in the perinatal planning of the mode and site of delivery.

Sequence and expression of the Escherichia coli K1 neuC gene product.

The nucleotide sequence of the neuC gene of the Escherichia coli K1 capsule gene cluster encodes a protein with a predicted molecular weight of 44,210 containing 391 amino acids. A chimeric protein with beta-galactosidase fused to the carboxy terminus of the neuC gene product (P7) was constructed and purified. Its amino-terminal sequence confirmed the prediction from the nucleotide sequence that the neuC gene overlaps the distal end of the neuA gene by a single base pair. Both the neuA and neuC genes are coexpressed under the control of a single upstream T7 or tac promoter, suggesting that neuA and neuC are part of an operon.

The tricyclic trimipramine in the treatment of subjective tinnitus.

We examined 26 consecutive patients with subjective tinnitus. All subjects were treated with the tricyclic antidepressant trimipramine in a double-blind study, each subject acting as his own control. All subjects were evaluated with pure tone audiometry, site of lesion testing, and auditory brain stem evoked response. The tinnitus assessment consisted of frequency and intensity matching, the determination of masking levels, and a subjective evaluation of severity. Plasma levels of trimipramine were monitored at regular intervals, and the Zung and Millon inventories were administered at the beginning and end of each study period. Nineteen subjects completed the study. Within the trimipramine group, one reported complete disappearance of his tinnitus, eight reported improvement, three no change, and seven that tinnitus was worse. Within the placebo group, eight reported improvement, seven no change, and four that tinnitus was worse. The natural history of tinnitus is such that what has been observed may reflect the evolution of the disease itself, rather than the effect of treatment. We feel that while tricyclics may not have been shown to be effective, the placebo effect played a significant role in the results obtained.

Test of the assumptions underlying comparative hearing aid evaluations.

Comparative hearing aid evaluations using NU-6 monosyllabic word lists were administered to adults with predominately high-frequency sensorineural hearing impairments who were randomly assigned to one of two experiments. In the first, three instruments were used that were electroacoustically similar and appropriate to the patients' hearing losses. In the second, the three hearing aids employed were electroacoustically quite different. Following an initial comparative hearing aid evaluation, the patients used the instruments during a trial-use week after which they ranked the aids in terms of benefit provided in daily communication. Following the trial-use week, the comparative hearing aid evaluation was repeated. The results suggest that significant interaid performance differences on the hearing aid evaluation are not likely to occur very often when the aids being evaluated are relatively homogeneous electroacoustically. In contrast, when electroacoustically heterogeneous instruments are evaluated, significant performance differences may occur frequently. Under such circumstances, however, the same instrument(s) would likely provide the best performance to most patients. The results further suggest that the reliability of standard monosyllabic word lists may not be adequate to detect typical interaid differences that occur in a comparative hearing aid evaluation and that the performance hierarchy is likely to change as the patient adjusts to amplification. Finally, the comparative hearing aid evaluation will not be a good predictor of success in daily communication unless relatively large performance differences exist among the instruments.

Electrical breakdown of bimolecular lipid membranes as an electromechanical instability.

The bimolecular lipid membrane (BLM) is modeled as a bulk elastic layer subject to a compressive electric force caused by applied voltages. Analysis of this model shows that a compressive instability develops when the electric stress exceeds a critical value. This instability tends to crush the film and thus rupture it. The predicted breakdown voltage, when compared with measured values for phosphatidylcholine and cholesterol, shows fair agreement, considering the uncertainty in the estimate of elastic parameters.