Survey of total arsenic and arsenic speciation in US-produced rice as a reference point for evaluating change and future trends.

Rice generally contains higher levels of arsenic than most terrestrial-based foods. Studies related to dietary intake of arsenic from rice must take into account arsenic speciation due to toxicity differences in arsenic species. In this study, microwave-assisted extraction with trifluoroacetic acid was used to prepare rice samples for arsenic speciation analysis by high-performance liquid chromatography-inductively coupled plasma mass spectrometry. Fifty-three samples collected directly from the fields in four major rice-producing states in 1980 and 1981 were analysed for total and speciated arsenic and the results were compared with each other and with results for several more recently collected samples from local markets. The average content of total arsenic was 210 ± 190 ng As g(-1). This study demonstrates that US rice samples with higher levels of total arsenic have higher levels of dimethylarsinic acid; however, inorganic arsenic levels, regardless of the total arsenic content, rarely exceed 150 ng As g(-1) dry weight. These data are consistent with more recent findings, thus establishing trends that arsenic content in US-grown rice has been relatively constant throughout the last 30 years. To the authors' knowledge, the presented data are unique in that they provide a historical reference point for arsenic distribution in US-produced rice. These data would be invaluable for several applications including long-term arsenic exposure studies, environmental clean-up assessments, and to establish models for future trends in arsenic contribution in total diet studies.

Symbolic interactionism as a theoretical perspective for multiple method research.

RATIONALE: Qualitative and quantitative research rely on different epistemological assumptions about the nature of knowledge. However, the majority of nurse researchers who use multiple method designs do not address the problem of differing theoretical perspectives. Traditionally, symbolic interactionism has been viewed as one perspective underpinning qualitative research, but it is also the basis for quantitative studies. Rooted in social psychology, symbolic interactionism has a rich intellectual heritage that spans more than a century. Underlying symbolic interactionism is the major assumption that individuals act on the basis of the meaning that things have for them. AIM: The purpose of this paper is to present symbolic interactionism as a theoretical perspective for multiple method designs with the aim of expanding the dialogue about new methodologies. CONCLUSION: Symbolic interactionism can serve as a theoretical perspective for conceptually clear and soundly implemented multiple method research that will expand the understanding of human health behaviour.

Critical theory: critical methodology to disciplinary foundations in nursing.

Increasingly in the nursing literature, theorists have examined the use of critical theory in nursing (especially as understood by Habermas) and many have advocated it as a research approach to guide knowledge development in nursing. There has been limited analysis, however, of critical theory's broader foundational implications for the discipline of nursing. Part of the difficulty stems from a failure to differentiate between the implications of Habermas's earlier work on knowledge interests and his later theory of communicative action. In this paper, Habermas's critical theory is explored along two dimensions: as a metatheoretical account of a methodology of critical theory as a research tradition; and as a theory of communicative action whose dialogical and normative assumptions have profound implications for a postfoundationalist grounding of nursing as a discipline and professional practice. The authors argue that critical theory is necessary for nursing and may be sufficient as a paradigmatic philosophical base for the discipline.

Evaluation of coronary flow reserve using myocardial contrast echocardiography in humans.

To evaluate the applicability of myocardial contrast echocardiography for the assessment of coronary blood flow reserve, 21 consecutive patients undergoing coronary angiography were studied. Only patients with a single left anterior descending lesion or normal coronary angiogram were included. Intracoronary injections of sonicated albumin were performed before and after the administration of intracoronary papaverine. Good quality studies at baseline and after the administration of papaverine were obtained in 14 of 21 patients. Ten patients had a significant (greater than 75%) single left anterior descending lesion and four had normal or insignificant lesions (70% or less stenosis) in the left anterior descending coronary artery. Time-intensity curves for the left anterior descending coronary artery region of interest were generated and then the peak contrast intensity (PCI), washout half-time (T1/2) and the area under the curve (AUC) were calculated. The post-papaverine increases in PCI and in the AUC, compared to baseline, were 55 +/- 22% and 102 +/- 14% in the four patients with 70% or less left anterior descending diameter stenosis serving as a control group and 3 +/- 25% and 40 +/- 10%, respectively, in the 10 patients with significant left anterior descending coronary artery disease (mean +/- 1 SD, P less than 0.01). In patients with normal coronary arteriography T1/2 increased after intracoronary injection of papaverine. In patients with severe lesions, either an increase or a decrease in T1/2 was observed. Significant left anterior descending coronary artery stenosis associated with impaired coronary blood flow reserve can be detected by failure of myocardial contrast echocardiographic parameters to increase after injection of papaverine. Mild and transient side effects were noted in three patients.

Variability in the transtricuspid gradient by continuous wave Doppler echocardiography.

In order to examine the day-to-day variability in the tricuspid regurgitant velocity jet and to determine the degree of physiological changes under exercise and volume loading, repeated echo cardiographic Doppler measurements in 1 single subject were performed.

Myocardial perfusion imaging by contrast echocardiography with use of intracoronary sonicated albumin in humans.

Sonicated albumin has been proposed as a near ideal echocardiographic contrast agent with little myocardial toxicity or hemodynamic effect. Its use has not yet been reported in humans, partly because of difficulties in preparation. With use of the newly modified sonication method, 10 ml of 5% albumin was sonicated for 75 s with a 5.0 ml slow infusion of air. This resulted in microbubbles with a mean diameter (+/- SD) of 5 +/- microns). Fourteen patients undergoing routine coronary angiography were studied. One patient had normal coronary arteries; the other 13 had significant coronary artery disease. In a subgroup of nine patients, sonicated albumin and sonicated diatrizoate meglumine sodium (microbubble diameter 9 +/- 3 microns) were injected several minutes apart, using the same technique. Videodensity-time curves were obtained from a region of interest in the myocardium. Corrected peak contrast intensity (baseline contrast intensity subtracted from peak contrast intensity, gray scale U/pixel) for sonicated albumin and for sonicated diatrizoate meglumine sodium was 51 +/- 26 and 52 +/- 19, respectively (p = 0.89). Washout half-time (T1/2) for the two agents was 5.5 +/- 4.5 and 16.0 +/- 12.2 s, respectively (p = 0.01). One patient with unstable angina experienced transient chest pain after repeated albumin injections. No electrocardiographic changes, blood pressure changes or wall motion abnormalities were observed. Administered by intracoronary injection, sonicated 5% albumin is a safe and effective echocardiographic contrast agent for myocardial perfusion imaging, yielding excellent myocardial contrast with physiologic washout time.

The meaning of visual impairment to visually impaired adults.

The purpose of this study was to explore the subjective meaning of visual impairment in the context of day to day life to adults whose visual impairment began in their adult years. Information was elicited through interviews from 25 people whose visual impairment ranged from an inability to see ordinary print to no light perception. Hermeneutics, as elaborated by Ricoeur, was used in the interpretation of the texts (transcribed interviews). A core variable, adjusting to a visual impairment, and five distinct categories, each with subcategories, emerged from the data. The meaning of visual impairment was derived from the manner in which the categories interrelated with the process of adjusting.

Quantitative assessment of the immediate results of coronary angioplasty by myocardial contrast echocardiography.

A low pressure gradient across the residual lesion and a minimal percent residual stenosis are markers of a successful coronary angioplasty. A more physiologic method of assessing the results of coronary angioplasty would involve assessment of myocardial perfusion in the affected coronary bed. Contrast two-dimensional echocardiography provides information about regional myocardial perfusion. To assess the correlation between pre- to postcoronary angioplasty changes in gradient or percent stenosis and the increase in peak contrast intensity, 23 consecutive patients were studied during coronary angioplasty. In 19 of the 23 patients, the coronary angioplasty was successful and in 15 (79%) of the 19, an adequate echocardiographic study was obtained. Mild and transient side effects of echo contrast were observed in 3 of the 15 patients. The gradient across the residual lesions decreased from 52 +/- 12 to 11 +/- 4 mm Hg (mean +/- SD), the diameter of the stenotic lesion decreased from 89 +/- 10 to 25 +/- 16% and corrected peak contrast intensity (peak contrast - baseline contrast in gray level U/pixel) increased from 15 +/- 16 to 50 +/- 26. All these differences were significant at the p less than 0.001 level. Corrected peak contrast intensity correlated exponentially with the decrease in pressure gradient (r = 0.82, p less than 0.001). The correlation curve had a greater increase in peak contrast intensity at gradient decreases greater than 45 mm Hg. Corrected peak contrast intensity did not correlate with decrease in diameter of the stenotic lesion (r = 0.19).

Blinded comparison of an "ultrasound stethoscope" and standard echocardiographic instrument.

We evaluated blinded readings by a physician using a miniature real-time "ultrasound stethoscope" compared with a "standard" echo instrument used by an independent physician. Size of all four cardiac chambers, wall motion, all four valves, thickness of interventricular septum and left ventricular posterior wall, and pericardial effusion were assessed in 66 patients. Each physician estimated whether he had answered the referring question and gave a final diagnosis. The physician using the ultrasound stethoscope correctly assessed chamber size in 87 percent of cases, segmental left ventricular wall motion in 71 percent of segments studied, and wall thickness in 88 percent of cases, and the diagnosis by the ultrasound stethoscope agreed with that made by the standard instrument in 68 percent of cases. The physician with the ultrasound stethoscope detected structural valvular problems (eg, stenosis) in 70 percent of cases but only detected flow abnormalities (eg, regurgitation) in 14 percent of cases. We conclude that (1) an experienced echocardiographer using an ultrasound stethoscope can detect most structural abnormalities found by a standard echocardiographic instrument; (2) chamber size, valvular stenosis, and pericardial effusions were accurately assessed; (3) the ultrasound stethoscope cannot be used to detect valvular regurgitation; and (4) limitations include the lack of freeze-frame, M-mode, hard copy, and Doppler.