Teaching medical students ultrasound to measure liver size: comparison with experienced clinicians using physical examination alone.

BACKGROUND: Ultrasound is increasingly recognized as a valuable addition to medical school curriculum. PURPOSE: In this study, we tested the ability of rising second year students to learn and conduct an ultrasound examination of vertical liver span at the point of care. METHODS: Six patients from a GI clinic volunteered to have their liver size measured. Ten students were trained to measure vertical liver span with ultrasound. Four physicians were recruited to measure liver span with standard methods. Student and physician measurements were compared to each other and to a reference ultrasound measurement for accuracy and variability. RESULTS: Compared to the reference, students overestimated liver size an average of 1.5 cm. Physicians underestimated liver size an average of 6.7 cm. Variance in student measurements for each patient was 10% to 17% and among physicians 20% to 50%. CONCLUSION: With limited instruction and clinical experience medical students can obtain liver size measurements with ultrasound that are more accurate and have less variability than those by physicians using physical examination. Given the ease with which students can learn to use ultrasound and the teaching and clinical value of ultrasound, ultrasound should be considered as a standard of medical education in the future.

Smoking as a risk factor for prostate cancer: a meta-analysis of 24 prospective cohort studies.

OBJECTIVES: We evaluated the relationship between smoking and adenocarcinoma of the prostate. METHODS: We pooled data from 24 cohort studies enrolling 21 579 prostate cancer case participants for a general variance-based meta-analysis. Summary relative risks (RRs) and 95% confidence intervals (CIs) were calculated separately for mortality and incidence studies. We tested the robustness of effect measures and evaluated statistical heterogeneity with sensitivity analyses. RESULTS: In the pooled data, current smokers had no increased risk of incident prostate cancer (RR = 1.04; 95% CI = 0.87, 1.24), but in data stratified by amount smoked they had statistically significant elevated risk (cigarettes per day or years: RR = 1.22; 95% CI = 1.01, 1.46; pack years of smoking: RR = 1.11; 95% CI = 1.01, 1.22). Former smokers had an increased risk (RR = 1.09; 95% CI = 1.02, 1.16). Current smokers had an increased risk of fatal prostate cancer (RR = 1.14; 95% CI = 1.06, 1.19). The heaviest smokers had a 24% to 30% greater risk of death from prostate cancer than did nonsmokers. CONCLUSIONS: Observational cohort studies show an association of smoking with prostate cancer incidence and mortality. Ill-defined exposure categories in many cohort studies suggest that pooled data underestimate risk.

Tetra[2,3-thienylene]: a building block for single-molecule electromechanical actuators.

Tetra(2,3-thienylene) is a thiophene-fused [8]annulene capable of undergoing redox-induced dimensional changes. The feasibility of efficiently translating this intrinsic function into a single polymeric electromechanical actuator is investigated by both experiment and density functional theory (B3LYP 6-31G[d,p]). A study of tetra(2,3-thienylene) and its homodimer reveal that redox-induced conformational change is conserved upon dimerization, a result that implicates similar behavior in the corresponding polymer. Theoretical predictions yield a maximum redox-induced dimensional change of 5.92% per repeat unit for the homodimer. Cyclic voltammetry reveals complete reversibility for the corresponding redox cycle. The latter two facts establish tetra(2,3-thienylene) as a suitable building block for single-molecule electromechanical actuators.