Ultrasonographic assessment of liver fibrosis with computer-assisted analysis of liver surface irregularities.

PURPOSE: The goal of this study was to evaluate the diagnostic accuracy of a software program that automatically analyzes the liver surface to diagnose significant fibrosis, by comparing it to the subjective analysis of a radiologist and to transient elastography (Fibroscan(®)). PATIENTS AND METHODS: One hundred fourteen patients with chronic liver disease were included in the study. They underwent liver biopsy, FibroScan(®) and ultrasonographic examination of the liver surface. The liver surface was analyzed by a software program that gave a score of surface irregularities. This evaluation was compared to subjective analysis by a radiologist expert in liver imaging and by two general radiologists. RESULTS: Fifty percent of the patients had significant fibrosis according to the METAVIR score. The AUROC for the diagnosis of significant fibrosis by the software program was 0.80 (95%CI: 0.71-0.87), which was equivalent (P=0.86) to that of FibroScan(®) (0.81; 95%CI: 0.71-0.89). Results of the subjective analysis by the expert radiologist were poorer than those of the software analysis (P=0.02) (AUROC=0.66; 95%CI: 0.56-0.75). Interobserver agreement among radiologists was poor (0.25

Targeted transgenesis at the HPRT locus: an efficient strategy to achieve tightly controlled in vivo conditional expression with the tet system.

The tet-inducible system has been widely used to achieve conditional gene expression in genetically modified mice. To alleviate the frequent difficulties associated with recovery of relevant transgenic founders, we tested whether a controlled strategy of transgenesis would support reliable cell-specific, doxycycline (Dox)-controlled transgene expression in vivo. Taking advantage of the potent hypoxanthine-aminopterin-thymidine selection strategy and an embryonic stem (ES) cell line supporting efficient germ-line transmission, we used hypoxanthine phosphoribosyltransferase (HPRT) targeting to insert a single copy tet-inducible construct designed to allow both glucocorticoid receptor (GR) and beta-galactosidase (beta-Gal) expression. Conditional, Dox-dependent GR and beta-Gal expression was evidenced in targeted ES cells. Breeding ES-derived single copy transgenic mice with mice bearing appropriate tet transactivators resulted in beta-Gal expression both qualitatively and quantitatively similar to that observed in mice with random integration of the same construct. Interestingly, GR expression in mice was dependent on transgene orientation in the HPRT locus while embryonic stem cell expression was not. Thus, a conditional construct inserted in single copy and in predetermined orientation at the HPRT locus demonstrated a Dox-dependent gene expression phenotype in adult mice suggesting that controlled insertion of tet-inducible constructs at the HPRT locus can provide an efficient alternative strategy to reproducibly generate animal models with tetracycline-induced transgene expression.

Age differences in feeling-of-knowing and confidence judgements as a function of knowledge domain.

For two semantic knowledge domains, general and computer-related, feeling-of-knowing (FOK) and confidence level (CL) ratings and their relative accuracy were assessed in young, middle-aged, and older adults, after test difficulty was equated across age groups. Global memory self-efficacy beliefs were also assessed for each domain. As expected, greater age was associated with poorer memory self-efficacy beliefs only in the computer domain. The oldest two groups were found to be more underconfident than young adults when rating their FOK but not their CL, for computer items but not for general items. Statistical control of age differences in memory self-efficacy beliefs in the relevant domain greatly reduced this age effect on computer-related FOK ratings. This finding suggests that absolute FOK judgments are more closely related to memory self-efficacy beliefs than are CL judgments. Gamma correlations between judgments and recognition performance revealed that all age groups were equally accurate in FOK and in CL judgments, in both domains.

Longitudinal investigation of exposure to arsenic, cadmium, and lead in drinking water.

Arsenic, cadmium, and lead have been associated with various forms of cancer, nephrotoxicity, central nervous system effects, and cardiovascular disease in humans. Drinking water is a well-recognized pathway of exposure to these metals. To improve understanding of the temporal dimension of exposure to As, Cd, and Pb in drinking water, we obtained 381 samples of tap and/or tap/filtered water and self-reported rates of drinking water consumption from 73 members of a stratified random sample in Maryland. Data were collected at approximately 2-month intervals from September 1995 through September 1996. Concentrations of As (range < 0.2-13.8 microg/L) and Pb (< 0.1-13.4 microg/L) were within the ranges reported for the United States, as were the rates of drinking water consumption (median < 0.1-4.1 L/day). Cd was present at a detectable level in only 8.1% of the water samples. Mean log-transformed concentrations and exposures for As and Pb varied significantly among sampling cycles and among respondents, as did rates of drinking water consumption, according to a generalized linear model that accounted for potential correlation among repeated measures from the same respondent. We used the intraclass correlation coefficient of reliability to attribute the total variance observed for each exposure metric to between-person and within-person variability. Between-person variability was estimated to account for 67, 81, and 55% of the total variance in drinking water consumption, As exposure (micrograms per day), and Pb exposure (micrograms per day), respectively. We discuss these results with respect to their implications for future exposure assessment research, quantitative risk assessment, and environmental epidemiology.

Metamemory Assessment and Memory Behavior in a Simulated Memory Professional Task

This study investigated metamemory knowledge related to a professional task and the relationships between metamemory knowledge and memory performance in a simulated professional task, which was a beverage-service job with memory constraints changes. Metamemory knowledge was assessed by interviewing student waiters about hypothetical recall tasks concerning lists of beverages. They then carried out a simulated beverage-service task, including a first paired-associate recall (beverage-customer), then a global recall (order to the bartender), followed by a second paired-associate recall (beverage-customer). Memory constraints were manipulated with table size and perceptive cues. Results revealed that in metamemory knowledge, task-strategy, and strategy were the only variables that were related. Metamemory knowledge produced an effect on all memory performance, whatever the constraints were. The implications of these findings for professional training are discussed in terms of strategy instruction for enhancing professional performance when memory demands change in the work environment. Copyright 1997Academic Press