The ensemble-averaged impedance cardiogram: An evaluation of scoring methods and interrater reliability

The interrater reliability and concurrent validity of two methods of scoring the ensemble-averaged impedance cardiogram were evaluated. Impedance cardiographic and electrocardiographic signals were recorded from 40 undergraduate men and women during a baseline rest period and a vocal mental arithmetic task period. Recordings were scored by four raters using a conventional method, involving ensemble averaging after careful editing of beat-to-beat waveforms, and a streamlined method, involving ensemble averaging without beat-to-beat editing. Intraclass correlations for interrater reliability exceeded .92, whereas intraclass correlations for concurrent validity exceeded .97, indicating excellent agreement between raters and scoring methods for all cardiac measures. The streamlined method was significantly faster than the conventional method. The results indicate that variations in beat-to-beat editing do not constitute a serious source of error in the ensemble-averaged impedance cardiogram and support the interrater reliability and concurrent validity of the two scoring methods.     

Motor assessment of cocaine/polydrug exposed infants at age 4 months.

Fifty nondrug-exposed infants and 74 cocaine/polydrug-exposed infants were evaluated on the Movement Assessment of Infants (MAI). The test provides an assessment of risk for motor dysfunction at age 4 months. There was a significant difference in total risk scores between the two groups of infants with cocaine-exposed infants having higher total risk scores (p less than .0001). Categorical risk scores revealed significant differences between the infants in muscle tone, primitive reflexes, and volitional movement with cocaine-exposed infants scoring more poorly in each category (p less than .0001). The groups scored differently on 11 of the 49 MAI items in those categories. Placement of infants within previously established ranges of risk scores (0-7 = no risk; 8-13 questionable risk; greater than 13 = high risk) revealed a significant difference in distribution between the two groups (p less than .0001). Earlier studies of the effects of intrauterine drug exposure have not revealed significant differences in motor development. The MAI demonstrated differential assessments of risk for motor dysfunction between cocaine-exposed and nondrug-exposed infants.     

Reliability and predictive value of salivary theophylline levels

The reliability and accuracy of salivary theophylline levels as a predictor of serum theophylline levels was investigated in 28 hospitalized chronic asthmatics, free of other chronic diseases, on continuous aminophylline infusion for greater than 24 hours. Twenty paired blood and saliva theophylline levels from 12 patients (group 1) were used to develop a formula for predicting serum theophylline levels from salivary levels. Twenty-one paired blood and saliva theophylline levels from 16 patients (group 2) were used to test the formula obtained. The formula predicted the serum theophylline concentration within 1.51 microgram/mL in 76% of the samples and within 1.88 microgram/mL in 100% of the samples. There was an excellent correlation between the predicted and actual serum theophylline concentrations, r = .93; thus under controlled conditions of steady-state pharmacokinetics in patients free of other diseases, salivary theophylline levels can be used to accurately predict serum levels.     

Should balloon angioplasty and stents have any role in operative intervention for lower extremity ischemia?

p < 0.01). Cumulative combined primary patency at 1 year by life-table methods was 82 ± 10% in the staged group and 83 ± 9% in the simultaneous group (p= 0.79). Mean follow-up was 13 ± 6 months. There is a role for balloon angioplasty and stent placement in operative revascularization of ischemic limbs in selected patients: patency was similar to that produced with the staged approach while the length of stay was shorter. Intraoperative balloon angioplasty is safe and effective and stents permit a measure of control in assuring an optimal intraoperative postangioplasty result.     

Novel antibody coating of a magnetizable solid phase for use in enzyme immunoassays.

Novel kinds of magnetizable particles have been prepared using the interaction between the complexing groups of phosphonic acid and polyvalent metal ions on the surface of Fe3O4 particles. After modification of monoclonal and polyclonal antibodies by the bifunctional chelating agent 2-(4-diazophenyl)-1-hydroxyethane-1,1-bisphosphonic acid, antibodies were immobilized at a ratio of 5-10 mg antibody molecules per ml Fe3O4 particles without loss of immunological reactivity. Very sensitive and fast immunoenzymometric assays for the quantitative determination of human interferon-alpha 1 and mouse immunoglobulins were developed using such particles. The advantages of the method include immobilization of proteins on magnetizable carriers without chemical modification of the carrier and the short assay time compared to conventional immunoenzymometric assays.