Reliability of three length measurement techniques in term infants.

PURPOSE: To describe and compare the intra- and interexaminer reliability of three length measurement techniques and to determine if the three measurement techniques yield significantly different measurements. METHOD: Two experienced, mother-baby nurses each obtained length measurements using the supine, paper barrier, and Auto-length measurement techniques twice each from 48 healthy term infants. The nurses were blind to their own and to each other's measurements. The order of the nurses and the order of the measurement techniques were randomized. RESULTS: For intraexaminer reliability, RN-1 had smaller mean absolute differences for the Auto-length measurements. RN-2 had similar mean absolute differences for all three measurement techniques. The percentage of differences < or = 1 cm were smallest for the supine measurements for RN-1 and not remarkably different between the measurement techniques for RN-2. For interexaminer reliability, the mean absolute differences between the pairs of measurements were smallest for the Auto-length measurements for Set-1 and for the paper-barrier measurements for Set-2. The percentage of differences < or = 1 cm between the pairs of measurements for Set-1 were not remarkably different and were lowest for the supine measurements for Set-2. The mean measurements obtained by the supine, paper-barrier, and the Auto-length measurements were respectively: 50.88, 50.33, and 49.67 cm. The differences between the means were statistically significant (X2 = 56.56, p = .0000). CONCLUSIONS: The differences between length measurements by individual examiners and pairs of examiners are relatively large. Clinicians should be aware of the magnitude of error in length measurements and should interpret length measurements with caution. These findings also demonstrate that all clinicians in any setting should use the same technique to obtain length measurements.     

Interference by plastics additives in the HPLC determination of microcystin-LR and -YR.

Plastics devices used for the field collection of water samples may contain plastics additives which will interfere with the HPLC determination of the cyanobacterial toxins microcystins. The presence of the additives resorcinol monobenzoate or 2,4-dihydroxybenzophenone can interfere with the determination of microcystin-LR. The presence of bisphenol A in plastics can interfere with the determination of microcystin-YR.     

Development of an inhalation unit risk factor for hexavalent chromium

A unit risk factor (URF) was developed for hexavalent chromium (CrVI). The URF is based on excess lung cancer mortality in two key epidemiological studies of chromate production workers. The Crump et al. (2003) study concerns the Painesville, OH worker cohort, while Gibb et al. (2000) regards the Baltimore, MD cohort. A supporting assessment was also performed for a cohort from four low-dose chromate plants (Leverkusen and Uerdingen, Germany, Corpus Christi, TX, Castle Hayne, NC). For the Crump et al. (2003) study, grouped observed and expected number of lung cancer mortalities along with cumulative CrVI exposures were used to obtain the maximum likelihood estimate and asymptotic variance of the slope (β) for the linear multiplicative relative risk model using Poisson regression modeling. For the Gibb et al. (2000) study, Cox proportional hazards modeling was performed with optimal exposure lag and adjusting for the effect of covariates (e.g., smoking) to estimate β values. Life-table analyses were used to develop URFs for each of the two key studies, as well as for supporting and related studies. The two key study URFs were combined using weighting factors relevant to confidence to derive the final URF for CrVI of 2.3E-03 per μg CrVI/m³.     

Factors Affecting Contrast-Detail Performance in Computed Tomography: A Review

This article reports on recent research findings into the factors that influence the detectability performance of different systems of computed tomography (CT) scanners. These systems include multidetector CT (MDCT) of different slice numbers, dual-source CT (DSCT), and cone-beam CT (CBCT). The introduction of more slices for MDCT, DSCT, and the new technology of CBCT increases the need to optimize the image quality and to examine the potential reduction of radiation doses to the patient. Low-contrast detail detectability is a method that has proven to be an appropriate evaluation method for this purpose. However, it is essential to recognize factors that affect detectability performance and understand how these factors influence image quality and radiation dose. It is argued that deep understanding of the influences of these factors is the key to image quality optimization in terms of contrast-detail detectability and radiation dose reduction. The purpose of this article is, therefore, to specify these factors and to explain their influence on detectability performance and hence on CT image quality. Further low-contrast detail studies are required to optimize imaging performance of different CT systems and scanners.     

Psychomotor stimulant effects ofd-amphetamine,MDMA and PCP: aggressive and schedule-controlled behavior in mice

The objective of the present experiments was to characterize psychomotor stimulant effects ofd-amphetamine, methylenedioxymethamphetamine (MDMA) and phencyclidine (PCP) on conditioned performance and on aggressive behavior in mice. In a novel protocol with alternating periods of schedule-controlled responding and aggressive behavior toward an intruder it was possible to assess a range of species-specific agonistic acts, postures, and motor activities as well as response rates and patterns engendered by a multiple Fixed Interval (FI) and Fixed Ratio (FR) schedule within the same animal. Initially, it was confirmed thatd-amphetamine and, less reliably, MDMA and PCP, increased FI, but not FR responding in mice. In the next experiment, mice confronted an intruder at the midpoint of the 1-h daily session; following the display of aggressive behavior, the rate of FI responding showed an amphetamine-like increase, whereas only a transient change occurred after non-aggressive encounters. Thirdly, using this new protocol, PCP,d-amphetamine and MDMA altered FI and FR responding in a way that was closely similar to the first experiment. Low PCP andd-amphetamine doses increased aggressive behavior erratically in certain individuals, but not reliably for the group. MDMA dose-dependently decreased aggressive behavior, and all drugs disrupted aggressive behavior at higher doses. The characteristic increases in walking and decreases in rearing after higher doses of PCP andd-amphetamine were greatly attenuated when the intruder was present. The rate-increasing effects ofd-amphetamine, MDMA and PCP occurred in the early portion of the fixed interval when the control rate is typically low; by contrast, low attack rates during the later portion of the confrontation with the intruder remained unaffected. The dose-dependent quantitatively and qualitatively differentiated profile of effects on schedule-controlled responding, motor activity and aggressive behavior suggest that the common properties ofd-amphetamine, MDMA and PCP pertain mostly to the disruption of organized behavior patterns and activation of repetitive motor routines at high doses, but point to different mechanisms for modulating aggressive behavior and conditioned performance at lower doses.     

Intravenous captopril in congestive heart failure

Hemodynamic and neurohumoral effects of intravenous captopril were studied in ten patients with severe chronic congestive heart failure (NYHA Functional Class III and IV). Incremental bolus doses of captopril, titrated to a maximum cumulative dose of 15 mg, were given at 10-minute intervals. Systemic arterial pressure, mean pulmonary capillary wedge pressure, systemic vascular resistance, mean pulmonary artery pressure, and heart rate decreased (P less than .05). Cardiac index and stroke volume index increased (P less than .05). Maximum hemodynamic effects occurred after cumulative doses of 7 mg and were seen within 30 minutes after initiation of therapy; responses persisted for 30-90 minutes after the last dose. Plasma renin activity increased, and plasma atrial natriuretic factor concentration decreased. No adverse effects were observed with the use of intravenous captopril. Thus, intravenous captopril produces rapid and favorable hemodynamic improvement in advanced heart failure patients.     

Comparison of subjective,pharmacokinetic, and physiological effects of marijuana smoked as joints and blunts

Recent increases in marijuana smoking among the young adult population have been accompanied by the popularization of smoking marijuana as blunts instead of as joints. Blunts consist of marijuana wrapped in tobacco leaves, whereas joints consist of marijuana wrapped in cigarette paper. To date, the effects of marijuana smoked as joints and blunts have not been systematically compared. The current within-subject, randomized, double-blind, placebo-controlled study sought to directly compare the subjective, physiological, and pharmacokinetic effects of marijuana smoked by these two methods. Marijuana blunt smokers (12 women and 12 men) were recruited and participated in a 6-session outpatient study. Participants were blindfolded and smoked three puffs from either a blunt or a joint containing marijuana with varying Δ⁹-tetrahydrocannabinol (THC) concentrations (0.0, 1.8, and 3.6%). Subjective, physiological (heart rate, blood pressure, and carbon monoxide levels) and pharmacokinetic effects (plasma THC concentration) were monitored before and at specified time points for 3 h after smoking. Joints produced greater increases in plasma THC and subjective ratings of marijuana intoxication, strength, and quality compared to blunts, and these effects were more pronounced in women compared to men. However, blunts produced equivalent increases in heart rate and higher carbon monoxide levels than joints, despite producing lower levels of plasma THC. These findings demonstrate that smoking marijuana in a tobacco leaf may increase the risks of marijuana use by enhancing carbon monoxide exposure and increasing heart rate compared to joints.