Event-related potentials to inspiratory flow-resistive loads in young adults: stimulus magnitude effects

Event-related potentials were recorded to brief presentations of four levels of inspiratory flow-resistive loads in young adults. We labeled the loads according to the level of resistance they provided subjectively: sub-threshold (0.34 cmH2O/l per s), near-threshold (4.01 cmH2O/l per s), intermediate (10.4cmH2O/l per s), and near-occlusion (57.5 cmH2O/l per s). No discernible ERPs were elicited by the undetected, sub-threshold stimulus but late components of the ERP (P2, N2, and P3) were observed to each of the three larger stimuli. They were related, in part, to behavioral judgments obtained during the stimulus periods. Both the latency and amplitude of the ERP components varied systematically as a function of stimulus magnitude, in a manner comparable to that observed in ERP paradigms using auditory and visual stimuli. Thus, the data show that event-related potentials to breathing are sensitive to physiologic effects of resistive loads present at the onset of inspiration. Respiratory ERPs may be used to infer sensory and perceptual responses to increases in airflow resistance and, accordingly, may relate to the perception of airflow obstruction in patient populations.     

Evaluation of enzyme-linked immunosorbent assay for the determination of polycyclic aromatic hydrocarbons in house dust and residential soil

Two commercially available enzyme-linked immunosorbent assays (ELISA) for total polycyclic aromatic hydrocarbon (PAH) and carcinogenic PAH (C-PAH) were evaluated. The testing procedures were refined for application to screening PAH and C-PAH in house dust and soil samples for human exposure studies. The overall method precision expressed as percent relative standard deviation (%RSD) of triplicate real world dust and soil samples was within +/- 29% (12-29%) for PAH ELISA and +/- 21% (5.9-21%) for C-PAH ELISA. Spike recoveries from real world dust/soil samples were 114 +/- 30% for phenanthrene from PAH ELISA and 120 +/- 8.2% for benzo[a]pyrene from C-PAH ELISA. The overall method accuracy for PAH and C-PAH assays cannot be assessed for multiple PAH components in dust/soil samples (which represent real-world samples), because of the assays' cross reactivities with other PAH components. Over 100 dust/soil samples from 13 North Carolina homes and 22 Arizona homes were analyzed by PAH and C-PAH assays, as well as by the conventional gas chromatography/mass spectrometry (GC/MS) method. Statistical analysis showed that dust/soil PAH data from ELISA and GC/MS methods are significantly different. In general PAH ELISA responses were higher than PAH GC/MS responses. The regression analysis showed that the linear relationship between ELISA and GC/MS measurements is not strong in the combined data. The relationship became stronger for the data from the same type of dust/soil samples. The screening performance of ELISA was evaluated based on the frequency distribution of ELISA and GC/MS data. The results indicated that the ELISA PAH and C-PAH assays cannot be used as a quantitative analytical tool for determining PAH in real-world dust/soil samples. However, the ELISA is an effective screening tool for ranking PAH concentrations in similar types of real world dust/soil samples.     

The development and psychometric validation of a brain cancer quality-of-life questionnaire for use in combination with general cancer-specific questionnaires

A self-report questionnaire module consisting of 24 items, comprising 5 scales and 7 single items, has been developed for measuring health-related quality of life in patients with brain cancer. Module development proceeded through several stages, including a listing of patient, family and health care professional concerns, the writing of items, field testing in 105 patients with brain cancer and subsequent item reduction and scale construction after multitrait scaling analysis and assessment of internal consistency (Cronbach's coefficient alpha). The final version of the module exhibits reasonable test-retest stability over a period of one week. Differences in the responses between patients with recently-diagnosed and recurrent cancer and between patients with a Karnofsky Performance Score (KPS) of 50-70 and 80-100 were in the expected direction, indicating that the module of questions is responsive to differing conditions. Patients with either mental confusion, motor deficit or dysphasia indicated problems in several domains and single items as compared to patients without these neurological deficits. Thus, differences in the responses to the items in the brain cancer module appear to reflect differences in neurological status. In addition, deteriorating neurological status was accompanied by a marked increase in emotional distress, future uncertainty and motor dysfunction. A comparison of the responses in the module with the KPS and with a modified Barthel Activities of Daily Living Index (BADLI) shows moderate correlations, primarily with scales and items that pertain to motor dysfunction, while other scales (such as emotional distress, visual disorder and communication deficit) and most single items are not associated with the KPS or BADLI. Since the emotional distress scale of the module was found to be highly correlated with the emotional function scale of the EORTC QLQ-C30, it could be omitted when the module is used in combination with the QLQ-C30. This would reduce the module to a total of 20 items with four scales and seven single items. The intention is to combine this module of questions with other core or general quality-of-life questionnaires when studying patients with brain cancer in clinical trials.     

The effect of unilateral partial facial paralysis and muscle ablation on craniofacial growth and development: an experimental study in the rabbit

The effect of unilateral partial facial nerve ablation and unilateral partial midface muscle ablation on craniofacial growth and development was investigated. New Zealand White rabbits (12 days old) were randomly assigned to three experimental groups: control group, to study normal craniofacial growth and development (n = 15); nerve ablation group, surgically induced unilateral paralysis of the buccal branches of the facial nerve (n = 15); and muscle ablation group, surgical unilateral ablation of the facial muscles innervated by the buccal branches of the facial nerve (n = 12). All animals were operated on at the age of 12 days; follow-up evaluations were performed at the ages of 2 months and 6 months. The age of 2 months represents the endpoint of the prepubertal craniofacial growth and development. At the age of 6 months, the animals are fully grown; therefore, the time period between 2 and 6 months is regarded as the pubertal growth period. Computerized dorsoventral roentgencephalometric (measurement of distances and angles) and computer tomographic (three-dimensional volumetric measurements) investigations were performed at both ages. Additional dry skull measurements were performed to determine more precisely the bone segments involved in the craniofacial growth alterations studied. The obtained results indicated the following. Unilateral partial facial paralysis involving the midface resulted in growth alterations analogous to those seen after unilateral total facial paralysis. The growth alterations were not to be seen as a growth restriction (reduction in bony volume) but as growth misdirections (alterations in shape). Major growth alterations were present in those regions closely related to the facial musculature, namely the nasal, maxillary, and premaxillary regions, resulting in a snout deviation toward the operated side. The growth alterations occurred during prepuberty and remained rather stable during puberty. Morphologic signs of muscle denervation were related to the craniofacial growth disturbances. The growth alterations after unilateral partial facial paralysis were mainly biomechanically induced, as they were analogous to those observed after unilateral midfacial muscle ablation. The fact that after unilateral midfacial muscle ablation at the age of 6 months the severity of the alterations had increased was attributed to the scar formation inherent to the surgical procedure.     

Secondary prevention of coronary heart disease

Despite the significant reduction in cardiovascular mortality during the past three decades, atherosclerotic coronary heart disease (CHD) remains the leading cause of death and disability in the United States. Randomized clinical trials in patients with CHD have provided convincing evidence that risk factor modification is beneficial in decreasing all-cause mortality and cardiovascular morbidity and mortality. Multifactorial coronary risk reduction provides the most substantial benefit. Coronary risk reduction is associated with a decrease in cardiovascular-related hospital admissions, a reduced need for myocardial revascularization procedures, and an improved quality of life for the patients so treated. Control of coronary risk factors is an integral component of the optimal care of the patient with CHD.     

Activity assays for characterizing the thrombolytic protein fibrolase

Characterization of the thrombolytic agent fibrolase was accomplished employing specific proteolytic and thrombolytic assays. This paper describes a method to measure enzyme proteolytic activity using the oxidized beta-chain of insulin as a substrate. Advantages of this method include a short incubation time for substrate cleavage followed by an isocratic HPLC method with a retention time of approx. 5 min. Proteolytic activity can be rapidly and easily quantitated with this procedure. An azocasein assay was also used to quantitate proteolytic activity. This method was optimized with respect to substrate concentration and incubation time allowing for the rapid quantitation of fibrolase activity. A thrombolytic assay is described which employs fibrin plate clearance and has the advantage of rapid and accurate quantitation compared with previously described methods. It also allows for the standardization of fibrolase in plasmin-equivalent units.