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Biomedical subjects

N C Edwards

Publications and source records attributed to N C Edwards.

At least 19 recordsLinked to original sources
PubMed1997

Ethnocultural predictors of postpartum infant-care behaviours among immigrants in Canada.

OBJECTIVES: To determine, among immigrants, what ethnocultural variables predict postpartum infant-care behaviours over and above other maternal and infant characteristics. METHODS: We recruited a cohort of immigrant women on hospital postpartum units. Data on predictor variables were collected during face-to-face interviews in the early postpartum period. Follow-up telephone interviews occurred at 3 months postpartum to assess infant-care behaviours. We identified 411 women meeting our eligibility criteria, of these 77.3% agreed to participate and 94% received follow-up interviews. RESULTS: In the first stage of a multiple linear regression analysis, maternal and infant predictors accounted for 24.2% of the variance in the 'Infant-Care Behaviours' score. In the second stage of model building, ethnocultural variables explained an additional 5.8% of the variance. Separate analyses for recent immigrants (resident in Canada less than 3 years) and less recent immigrants (3 or more years) yielded some differences in predictors. Among recent immigrants, worries about the infant's health, mother's education and an interaction term (current immigration status by parity) were significant predictors, explaining 23% of the variance. Among less recent immigrants, worries about the baby's health, prenatal class attendance, marital status and official language comprehension ability explained 37.7% of the variance. CONCLUSIONS: Our results indicate that assessing ethnocultural characteristics, in addition to maternal and infant characteristics, improves the prediction of 'Infant-Care Behaviours' scores.

Adolescent↗
PubMed1995

Comparison between 201Tl and 99mTc sestamibi uptake during adenosine-induced vasodilation as a function of coronary stenosis severity.

BACKGROUND: Myocardial uptake of either 201Tl or 99mTc-sestamibi (sestamibi) is known to plateau at high coronary flow rates. However, few direct comparisons have been made between these tracers to determine what effect differences in the uptake plateau for the two tracers may have on the detection of coronary stenoses of various severities. METHODS AND RESULTS: Twenty-two dogs were instrumented with flow transducers on the left anterior descending (LAD) and circumflex (LCx) arteries. In 6 nonstenotic dogs, adenosine was infused directly into the LAD, whereas 16 dogs with either critical (n = 7) or mild (n = 9) LAD stenoses received an intravenous infusion. At peak flow, 201Tl (0.5 mCi), sestamibi (5 to 8 mCi), and radiolabeled microspheres were injected simultaneously. Five minutes later, dogs were killed, and ex vivo imaging of heart slices and gamma-well counting of multiple myocardial samples was performed. Neither 201Tl nor sestamibi uptake increased in direct proportion to flow. In the 6 nonstenotic dogs, a fivefold increase in LAD flow increased 201Tl and sestamibi uptake by only 202 +/- 6% and 138 +/- 4%, respectively (P < .0001). In the dogs with critical stenosis, the ratios of stenotic to normal activity by well counting for 201Tl (0.37 +/- 0.05) and sestamibi (0.53 +/- 0.06) underestimated the microsphere-determined flow disparity (0.17 +/- 0.03) (P < .005), but the degree of underestimation was greater for sestamibi (P = .001). Similarly, in the dogs with mild stenosis, the stenotic-to-normal ratio for 201Tl (0.62 +/- 0.04) approximated the flow ratio (0.43 +/- 0.04) better than sestamibi (0.79 +/- 0.03) (P < .0001). Sestamibi defects, however, were visually identifiable on the images of the myocardial slices. By image quantification, sestamibi defect magnitude (LAD-to-LCx count ratio) in the critical stenosis group (0.62 +/- 0.05) was significantly less than in the mild stenosis group (0.80 +/- 0.02) (P < .01). CONCLUSIONS: Thus, with adenosine-induced hyperemic flow, both 201Tl and sestamibi significantly underestimated the magnitude of the flow disparity between stenotic and normal perfusion beds. The degree of underestimation was greater for sestamibi. The clinical implication of these experimental findings for vasodilator perfusion imaging remains to be determined, since factors such as greater redistribution and scatter with 201Tl could offset its advantages.

Adenosine↗
PubMed1994

Redistribution of 99mTc-sestamibi and 201Tl in the presence of a severe coronary artery stenosis.

BACKGROUND: 99mTc-labeled methoxyisobutyl isonitrile (99mTc-sestamibi) is a myocardial perfusion agent that clears slowly from the myocardium. This study evaluates the early and late myocardial distributions of 99mTc-sestamibi and 201Tl in the presence of low-flow ischemia to determine whether 99mTc-sestamibi demonstrates rest "redistribution." METHODS AND RESULTS: Low-flow ischemia was produced in 18 anesthetized, open-chest dogs by partial occlusion of the left anterior descending coronary artery. Dogs were injected intravenously with 99mTc-sestamibi, 301Tl, and radiolabeled microspheres during sustained low-flow ischemia. The hearts were excised either 20 minutes (group 1, 10 dogs) or 2.5 hours (group 2, 8 dogs) after injection for gamma well counting to evaluate the early and late myocardial distributions of these radiotracers, relative to microsphere flow. The early myocardial distributions of 99mTc-sestamibi and 201Tl were comparable and correlated with the flow deficit (group 1). We observed a significant difference in myocardial 201Tl (P = .005) and 99mTc-sestamibi (P < .0001) activities between groups 1 and 2 dogs relative to flow, suggesting some redistribution of both tracers. Myocardial slices were imaged postmortem with a gamma camera, and 99mTc-sestamibi defect intensity was quantified. There was excellent correlation (r = .97) between the early relative 99mTc-sestamibi defect intensity on postmortem images and the flow deficit (group 1). Among group 2 dogs, the correlation was good (r = .87), but the 99mTc-sestamibi defect was less severe than the flow deficit, again suggesting redistribution. CONCLUSIONS: The myocardial distributions of 99mTc-sestamibi and 201Tl early after injection are comparable and proportional to flow. Under conditions of sustained low flow, there was detectable rest "redistribution" of 99mTc-sestamibi verified by both gamma well counting and high-resolution postmortem imaging of myocardial slices. Whether this degree of 99mTc-sestamibi rest redistribution will be detectable by serial clinical imaging remains uncertain. Nevertheless, these data suggest that imaging should be delayed after the resting injection of 99mTc-sestamibi when assessing myocardial viability in the presence of a critical stenosis.

Animals↗
PubMed1993

99mTc-sestamibi uptake and retention during myocardial ischemia and reperfusion.

BACKGROUND: 99mTc-methoxyisobutyl isonitrile (Sestamibi) is a new perfusion agent that has shown promise for the noninvasive detection of myocardial salvage after coronary reperfusion in acute myocardial infarction. The objective of this study was to further validate that myocardial uptake and retention of Sestamibi after reperfusion in a canine myocardial infarction model are markers of tissue viability. The hypotheses tested were that if Sestamibi is given early after reperfusion and myocardial uptake is quantitated soon afterward, the degree of ultimate myocardial salvage will be overestimated, and that there will be continued loss of myocardial Sestamibi from ischemic tissue during 3 hours of reperfusion due to accelerated release of Sestamibi from cells already irreversibly injured during the phase of coronary occlusion, reperfusion injury to myocytes still viable early after reflow, or a combination of both mechanisms. METHODS AND RESULTS: In protocol 1, 8.0 mCi Sestamibi was injected intravenously in anesthetized dogs 2-5 minutes after reperfusion preceded by 3 hours of left anterior descending coronary artery (LAD) occlusion. Animals were killed either 5 minutes (n = 7) or 3 hours (n = 9) after Sestamibi administration. Mean endocardial Sestamibi activity was 74 +/- 3% of nonischemic activity in dogs killed early and 31 +/- 2% of nonischemic activity in dogs killed late after Sestamibi administration, indicating myocardial loss of Sestamibi during 3 hours of reflow. Regional flow (percent nonischemic) at the time of Sestamibi administration (2-5 minutes after reperfusion) was comparable in dogs killed early (144 +/- 23%) and dogs killed late (118 +/- 4%, p = NS). In protocol 2, Sestamibi was given intravenously at baseline under normal conditions followed by 3 hours of LAD occlusion and either 4 (n = 6), 30 (n = 9), or 180 minutes (n = 10) of reperfusion. At postmortem, myocardial slices were imaged for quantification of defect magnitude and regional flow (radiolabeled microspheres), and tissue Sestamibi activities were determined by gamma well counting. Coronary sinus Sestamibi activity was serially measured. In these dogs, which were preloaded with Sestamibi at baseline, 3 hours of LAD occlusion followed by 3 hours of reperfusion resulted in a loss of Sestamibi in the endocardial zone of the ischemic region to 40 +/- 6% of nonischemic levels (p < 0.0001). This loss corresponded to a sustained elevation of coronary sinus activity throughout the reflow period. The loss of myocardial Sestamibi was significantly greater than that observed in dogs killed 4 or 30 minutes after reflow. Defect magnitude also worsened over 3 hours of reperfusion as assessed by gamma camera imaging of slices of the excised hearts. CONCLUSIONS: These experimental data suggest that Sestamibi uptake and retention are dependent on myocardial viability as well as regional flow. If Sestamibi is administered early after reperfusion and imaging is performed soon afterward, the degree of myocardial salvage could be significantly overestimated.

Animals↗
PubMed1992

Influence of subendocardial ischemia on transmural myocardial function.

The relationship between regional myocardial perfusion and function under ischemic conditions was examined by using a nontraumatic single-crystal pulsed Doppler system that permits complete transmural assessment of myocardial thickening. Sixteen open-chest dogs underwent either 50 (n = 4) or 180 (n = 12) min of partial coronary artery occlusion. Simultaneous measurements of myocardial thickening fraction (TF) and microsphere-determined blood flow (BF) were taken in the subepicardial, midwall, and subendocardial thirds of the left ventricular wall. During ischemia, there was an excellent correlation between BF and TF in the subendocardium. Mean subendocardial BF was reduced to 0.45 +/- 0.3 ml.min-1.g-1, resulting in a subendocardial TF of 0.8 +/- 19%. Although subepicardial BF was relatively preserved at 1.03 +/- 0.4 ml.min-1.g-1, subepicardial TF was diminished markedly and not significantly different from subendocardial TF. Subepicardial and midwall TF were highly dependent on subendocardial flow rather than on the actual flow in these areas. Hence these studies show a marked dependence of transmural myocardial function on subendocardial blood flow. Outer wall function is more dependent on subendocardial than subepicardial blood flow.

Animals↗
PubMed1989

Traditional Mende Society in Sierra Leone: a sociocultural basis for a quantitative research study.

Traditional Birth Attendants (TBAs) deliver more than 85% of the infants born in rural Sierra Leone. These midwives, who learn their skills from practice or a predecessor, are powerful women in the pervasive, secret Sande Society. Formal training programs have been established to strengthen the maternal and infant practices of these TBAs. Designing and implementing a quantitative research study to examine the effectiveness of two methods of TBA training required a strong sociocultural basis. The study was undertaken in a predominantly Mende ethnic area of Sierra Leone. I describe the significant ways in which the values and traditions of the Mende influenced the choice of research methods. Finally, I present critical questions researchers should ask to design a study that fits with the sociocultural fabric of their target population.

Culture↗
PubMed1989

Payment for deliveries in Sierra Leone.

The type and amount of payment for deliveries were investigated in 1982 during a survey on health status in two districts. Data on the payments made for 83.5% of the 2591 deliveries in 535 randomly selected study villages showed that the most common method of payment was in cash only. Payments in kind were mostly given to trained traditional birth attendants (TBAs) (for 38.1% of their deliveries) and rare for professional staff (2.9% of deliveries). The total amount paid for a delivery differed significantly with the type of birth attendant (P less than 0.00001) and the place of delivery (hospital, peripheral health unit or home) (P less than 0.00001). The total average payment for a delivery was highest for professional birth attendants (Le 16.60) and lowest for untrained TBAs (Le 4.85) (Le 2 = approx. US+ 1 at the time of the study). The outcome of a delivery had a significant effect on the amount paid. Payments were significantly higher for stillbirths than for live births among professional and auxiliary birth attendants (P less than 0.0001). However, the trained and untrained TBAs received less payment for stillbirths (Le 2.25) than for live births (Le 4.89) (P = 0.0146). The results show that there are several levels of financial disincentives for pregnant women requiring the services of trained auxiliary or professional health workers at the time of delivery.

Cross-Sectional Studies↗
PubMedDate not supplied

The provision of public health nursing follow-up services for postnatal clients in Ontario: a cross-sectional survey.

We did a cross-sectional survey of official health agencies in Ontario in 1990 to assess methods of providing postnatal services. The response rate was 78.6%. We found that diverse methods of postnatal follow-up are offered although home visits remain a primary mode of service delivery. There are significant differences in the timing of home and telephone visits and postnatal group sessions.

Cross-Sectional Studies↗
PubMedDate not supplied

The hospital liaison process: identifying risk factors in postnatal multiparas.

Postnatal home visiting has been a routine part of the public health nurse's role in Canada for decades. Resource limitations in recent years have required Health Units to justify programming choices and in some cases have dictated a shift toward more intensive service provision to high risk clients. This study examined the screening accuracy of a tool developed for use by hospital liaison nurses to identify multiparas in need of home visiting. Results showed poor agreement between client information collected by the hospital liaison nurse and the assessment done by the PHN in the clients' home, even when explicit referral criteria were used. Changes are required in the referral process to effectively screen postnatal clients in need of further services.

Canada↗
PubMedDate not supplied

Important considerations in the use of ethnicity as a study variable.

Ethnicity is widely used as a study variable by community health researchers. However, there is little consistency in the definition of ethnicity and the process by which ethnicity is assigned. Potential problems in the use of ethnicity as a study variable are discussed as well as suggestions for improvements.

Community Health Services↗
PubMedDate not supplied

Tobacco use and ethnicity: the existing data gap.

Tobacco use contributes substantially to the burden of illness throughout the world. Significant efforts have been made to design health promotion programs for the prevention and cessation of tobacco use in North America. However, most of these programs have been planned and implemented on the basis of needs assessments conducted among the dominant cultural group. Evidence exists that lifestyle modification and tobacco cessation programs must be culturally relevant to ensure successful outcomes. A review of the literature from nursing, anthropological and epidemiological perspectives suggests that there is a paucity of data available on the largely culture-dependent values which influence the decision to use tobacco in those groups which comprise the Canadian multicultural mosaic. The interpretation of results from existing studies is limited by a number of recurrent methodological flaws. The implications of this review for future research and public health planning are discussed. The development of culturally appropriate programs directed at the prevention and cessation of tobacco use remains a significant challenge for health professionals.

Canada↗