A qualitative study of parental modeling and social support for physical activity in underserved adolescents

This study obtained qualitative data to assess how parental role modeling and parental social support influence physical activity in underserved (minority, low-income) adolescents. Fifty-two adolescents (22 males, 30 females; ages 10-14 years, 85% African-American) participated in a focus group (6-10 per group, same gender). Focus groups were audiotaped, transcribed and coded by independent raters. Inter-rater reliabilities indicated adequate agreement [inter-rater reliability (r) = 0.84]. Themes were identified for parental role modeling and parental social support. Regarding parental role modeling, adolescents reported that parents engaged in a variety of different types of physical activities with their children such as walking, cycling and playing basketball; however, activity was infrequent. Sex differences were noted in parental social support indicating that female adolescents reported receiving more emotional and negative support for physical activity (being required to play outside with a sibling), while boys reported receiving more tangible types of support for physical activity. Adolescents also generated ideas on how to increase parental social support and in particular tangible support was highlighted as important by both males and females. This study suggests that future interventions should focus on improving parental engagement and tangible support that involve direct participation from parents in physical activities with their adolescents.

Using process evaluation for program improvement in dose, fidelity and reach: the ACT trial experience

Background

The purpose of this study was to demonstrate how formative program process evaluation was used to improve dose and fidelity of implementation, as well as reach of the intervention into the target population, in the "Active by Choice Today" (ACT) randomized school-based trial from years 1 to 3 of implementation.

Methods

The intervention integrated constructs from Self-Determination Theory and Social Cognitive Theory to enhance intrinsic motivation and behavioral skills for increasing long-term physical activity (PA) behavior in underserved adolescents (low income, minorities). ACT formative process data were examined at the end of each year to provide timely, corrective feedback to keep the intervention "on track".

Results

Between years 1 and 2 and years 2 and 3, three significant changes were made to attempt to increase dose and fidelity rates in the program delivery and participant attendance (reach). These changes included expanding the staff training, reformatting the intervention manual, and developing a tracking system for contacting parents of students who were not attending the after-school programs regularly. Process outcomes suggest that these efforts resulted in notable improvements in attendance, dose, and fidelity of intervention implementation from years 1 to 2 and 2 to 3 of the ACT trial.

Conclusion

Process evaluation methods, particularly implementation monitoring, are useful tools to ensure fidelity in intervention trials and for identifying key best practices for intervention delivery.

Heart Healthy and Ethnically Relevant (HHER) Lifestyle trial for improving diet and physical activity in underserved African American women

BACKGROUND

African American women are at increased risk for CVD morbidity and mortality relative to white women. Physical inactivity and poor dietary habits are modifiable health behaviors shown to reduce CVD risk. Community health centers have the potential to reach large numbers of African Americans to modify their risk for CVD, yet few lifestyle counseling interventions have been conducted in this setting.

METHODS

The HHER Lifestyle trial is a randomized controlled trial to compare the effects of a standard care intervention (provider counseling, nurse goal setting, and educational materials) to a comprehensive intervention (standard care intervention plus 12 months of telephone counseling and tailored print materials) on changes in physical activity and dietary fat consumption in financially disadvantaged African American women at 6 and 12 months. Secondary outcomes are body mass index, central adiposity, and total cholesterol. Potential mediators of outcome are self-efficacy for overcoming barriers, social support, and decisional balance.

RESULTS

African American women (N=266; 130 standard care, 136 comprehensive intervention) 35 years and older from nine clinics within two community health centers were enrolled. Most participants were overweight or obese with existing chronic health conditions.

CONCLUSION

The HHER Lifestyle trial is unique in that it targets financially disadvantaged African American women from community health centers, incorporates a standard care intervention into a routine clinical appointment, and includes a comprehensive process evaluation. The design will permit further research examining the added effect of regular telephone counseling and tailored print materials to a primary care provider and nurse intervention.

New perspectives on health disparities and obesity interventions in youth

OBJECTIVE

This article reviews intervention studies that address health disparities and the increasing rate of obesity in minority youth. The review focuses on interventions that target obesity-related behaviors (diet, physical activity, sedentary behaviors) and adiposity outcomes (body mass index) in minority children and adolescents.

METHODS

A conceptual framework is presented that integrates ecological, cultural, social, and cognitive approaches to reducing obesity in ethnically diverse youth. The review highlights effective interventions in minority youth and distinguishes between culturally targeted and culturally tailored components.

RESULTS

A limited number of studies have been conducted that target obesity-related behaviors and adiposity outcomes in minority youth. The most successful interventions for minority youth have incorporated culturally targeted and culturally tailored intervention components using multi-systemic approaches.

CONCLUSIONS

Further research is needed that focuses on testing the efficacy of theoretically based approaches that integrate culturally appropriate program elements for improving obesity-related behaviors and adiposity outcomes in minority youth.

Commentary for Health Psychology special issue: theoretical advances in diet and physical activity interventions

This issue of Health Psychology includes original contributions for advancing research on theoretical issues such as mediation and moderation effects in promoting healthy diet and physical activity behavior change. This special issue was developed to highlight some of the fundamental issues from a biological, cognitive, social, and environmental perspective for understanding the impact of intervention effects on behavior change processes and ultimate health. Given the increasing prevalence of health-related problems, such as the increasing prevalence of obesity and diabetes in the United States, the perspective presented in this issue should be very useful to researchers, scientists, scholars, and a wide range of health professionals who hope to curb these critical public health problems.

Physical activity influences in a disadvantaged African American community and the communities' proposed solutions

The purpose of this assessment is to increase our understanding of how safety and environmental factors influence physical activity among African American residents living in a low-income, high-crime neighborhood and to get input from these residents about how to best design physical activity interventions for their neighborhood. Twenty-seven African American adult residents of a low-income, high-crime neighborhood in a suburban southeastern community participated in three focus groups. Participants were asked questions about perceptions of what would help them, their families, and their neighbors be more physically active. Two independent raters coded the responses into themes. Participants suggested three environmental approaches in an effort to increase physical activity: increasing law enforcement, community connectedness and social support, and structured programs. Findings suggest that safety issues are an important factor for residents living in disadvantaged conditions and that the residents know how they want to make their neighborhoods healthier.

An overview of "The Active by Choice Today" (ACT) trial for increasing physical activity

BACKGROUND

Although school-based behavioral interventions for increasing physical activity (PA) in children and adolescents have been conducted, little evidence suggests that these curriculum-based approaches lead to increases in overall activity outside of program days. The overall goal of the "Active by Choice Today" (ACT) trial is to expand the body of knowledge concerning the factors that influence long-term increases in PA in underserved adolescents (low socioeconomic status, minorities) during their middle school years.

DESIGN AND SETTING

An overview of the ACT study design, theoretical framework, process evaluation, and primary hypotheses is presented. The trial involves twenty-four middle schools (1560 6th graders) in South Carolina that are randomly assigned to one of two after-school programs (motivational and life skills intervention, or general health education).

INTERVENTION

The intervention integrates constructs from Self-Determination and Social Cognitive Theories to enhance intrinsic motivation and behavioral skills for PA. The intervention targets skill development for PA outside of program days and the after-school program social environment (autonomy, choice, participation, belongingness, fun, enjoyment, support) is designed to positively impact cognitive mediators (self-efficacy, perceived competence), and motivational orientation (intrinsic motivation, commitment, positive self-concept). MAIN HYPOTHESES/OUTCOMES: It is hypothesized that the 17-week motivational and life skills intervention will lead to greater increases in moderate-to-vigorous PA (based on 7-day accelerometry estimates) at post-intervention as compared to the general health education program.

CONCLUSIONS

Implications of this innovative school-based trial are discussed.

Formative evaluation of a motivational intervention for increasing physical activity in underserved youth

The present study was designed to develop an innovative motivational intervention (based on Self-Determination Theory and Social Cognitive Theory) to increase physical activity (PA) in underserved adolescents. Sixty-four adolescents (35 females, 29 males; 50% minority; 65% on reduced lunch program; ages 11-13 yr) participated in either an 8-week motivational intervention after-school (n = 32) or a typical after-school program (n = 32). The conceptual framework for the intervention targeted the social environment (perceived autonomy, perceived social support, participation, fun), cognitive mediators (perceived choice, self-efficacy, and relatedness/belongingness), and motivational orientation (intrinsic motivation, commitment, positive self-concept). Formative evaluation data was collected by staff through daily forms throughout the 8-week program and through observational data completed by independent objective observers during 2 weeks of the program. The major themes that were identified addressed theoretical concepts regarding the intervention and logistical issues in delivering the intervention. The data revealed information regarding the importance of the cognitive appropriateness of the PA and motivational activities, the environmental climate for promoting nurturing relationships, developing specific strategies for increasing intrinsic rather than extrinsic reinforcement, and developing methods for preventing social "cliques" and gender conflicts to maintain an appropriate level of support in the social climate. Themes for training staff included focusing on team building, leadership, and nurturing. This formative evaluation is being used to formalize a randomized trial to test the effects of a student-centered motivational intervention on increasing PA in underserved 6th graders.

Awareness and use of a university recreational trail

The purpose of this study was to assess awareness and use of a university recreational trail. The authors used an Internet questionnaire developed by the university's Institutional Research Department, with questions derived from the Environmental Supports for Physical Activity Questionnaire and the National College Health Risk Behavior Survey Physical Activity Module. Four hundred and sixty-seven undergraduate college students participated. Ninety-one percent of students reported being aware of the trail, and 73% reported using the trail. Sixty-four percent of students reported seeing signage referring to the recreational trail. Sixty-seven percent of the students reported using the trail once in the past week, 7% reported using the trail twice in the past week, and only 2% of the students reported using the trail more than 3 times in the past week. Sixty-two percent reported using the trail with another individual. Students who were aware of the trail were more likely to use the trail. However, of the individuals who used the trail, the majority only used the trail 1 day a week. University programming is needed to increase trail usage among college students.

Outcome expectations, barriers, and strategies for healthful eating: a perspective from adolescents from low-income families

To better understand outcome expectations, barriers, and strategies for healthful eating, 5 structured focus groups were conducted with adolescents from low-income families (n = 48; 83% Black students; 10-14 years old). The focus group questions dealt with healthful eating in different settings: home, school, and other eating establishments. Results suggested that healthful eating is important to this population, but perceived barriers prevent the consistent consumption of healthful foods. Strategies suggested by participants to increase healthful eating (eg, parents and schools making healthy foods that look and taste good more available) should be considered when developing nutrition interventions for adolescents from low-income families.

A preliminary test of a student-centered intervention on increasing physical activity in underserved adolescents

BACKGROUND

Previous studies have shown that choice and self-initiated behavior change are important for increasing intrinsic motivation and physical activity (PA), however, little of this research has focused on underserved adolescents.

PURPOSE

This study examined the effects of a 4-week student-centered intervention on increasing PA in underserved adolescents.

METHODS

Twenty-eight students in the intervention school were matched (on race, percentage on free or reduced-price lunch program, gender, and age) with 20 students from another school who served as the comparison group (30 girls, 18 boys; ages 10-12 years; 83% African American; 83% on free or reduced-price lunch). The student-centered intervention was consistent with self-determination (motivation) theory and social cognitive theory in that it emphasized increasing intrinsic motivation and behavioral skills for PA. Intervention adolescents took ownership in selecting a variety of PA activities in which to participate, and they generated coping strategies for making effective PA behavior changes.

RESULTS

Intervention participants showed greater increases in accelerometer estimates of time spent in moderate PA, moderate-to-vigorous PA, and vigorous PA from baseline to Week 4 of the intervention than the comparison group. Intervention participants also showed greater increases in PA motivation and positive self-concept for PA than comparison adolescents.

CONCLUSIONS

This study provides preliminary evidence that increasing adolescent involvement and choice of activities may be important in developing future PA interventions for underserved adolescents.

Perceptions of environmental supports for physical activity in African American and white adults in a rural county in South Carolina

INTRODUCTION

This study examined the association between perceptions of social and safety-related environmental attributes and physical activity (PA) and walking in African American and white adults.

METHODS

In a random-digit-dial telephone survey, 1165 adults in a rural county in South Carolina answered questions about their perceptions of social and safety-related environmental supports for PA and their overall PA and walking behavior. Social perceptions included whether neighbors could be trusted or were perceived to be physically active. Safety-related perceptions included neighborhood safety, the safety of public recreation facilities, problems with unattended dogs, traffic volume, and streetlight quality. Logistic regression models were used to examine the associations between environmental supports and PA and walking stratified by race.

RESULTS

No association between perceived neighborhood environmental supports and PA or walking was observed in African Americans. Among whites, individuals who perceived their neighbors as active were twice (95% confidence interval [CI], 1.19-3.25) as likely to report meeting the recommendation for PA compared with individuals who did not report their neighbors as active. Whites who perceived their neighbors as active were 2.5 times (95% CI, 1.54-4.08) as likely to report meeting the recommendations for walking than whites who did not, and whites who perceived their neighborhoods as safe were 1.8 times (95% CI, 1.03-3.12) as likely to report meeting the recommendations for walking than whites who did not.

CONCLUSION

These data indicate that perceptions of certain social and safety-related environmental supports were strongly associated with meeting the recommendations for PA and walking among white but not African American adults.

How many days of pedometer monitoring predict weekly physical activity in adults?

BACKGROUND

The study purpose was to establish the number (and type) of days needed to estimate mean pedometer-determined steps/day in a field setting.

METHODS

Seven days of data were collected from 90 participants (33 males, age = 49.1 +/- 16.2 years, BMI = 27.2 +/- 4.1 kg/m(2); 57 females, age = 44.8 +/- 16.9 years, BMI = 27.0 +/- 5.9 kg/m(2)). Mean steps/day were computed for all 7 days (the criterion), each single day, and combinations of days. Analyses included repeated measures ANOVA, intra-class correlations (ICC), and regression.

RESULTS

There was a significant difference (P < 0.001) between days. The difference was limited to Sunday and accounted for 5% of the variance. ICC analyses indicated a minimum of 3 days is necessary to achieve a reliability of 0.80. The adjusted R(2) was 0.79 for a single day (specifically Wednesday), 0.89 for 2 days (Wednesday, Thursday), and 0.94 for 3 days (Wednesday, Thursday, Friday). Sunday was the last day to enter the model.

CONCLUSIONS

Although there is a statistical difference between days, there is little practical difference, and the primary distinction appears limited to Sunday. Although a single day of collection is not acceptable, any 3 days can provide a sufficient estimate.

Brief report: a qualitative study of gender preferences and motivational factors for physical activity in underserved adolescents

OBJECTIVE

This study used focus groups to identify preferences for physical activity (PA) and motivational themes for increasing PA in underserved adolescents.

METHODS

Fifty-one adolescents, on the free lunch program (25 males and 26 females; ages 10-13 years; 72% African-American, 19% white, and 9% other minorities) participated in focus groups (6-10 children per group; same gender). The data were transcribed and coded into themes. A content analysis was performed using QSR NVivo.

RESULTS

Boys rated their favorite activities as playing basketball, football, soccer, and baseball. Girls rated their favorite activities as playing basketball, swimming, and roller-skating. For motivational themes, boys and girls most frequently stated that they would participate in PA if it was a fun, provided a health benefit, and if there were a variety of choices offered. Being involved with friends was also identified as important to both boys and girls.

CONCLUSIONS

The findings from this qualitative study suggest that including components of choice and a variety of physical activities may be important elements for intervention programs in underserved adolescents.

Race differences in cardiovascular and cortisol responses to an interpersonal challenge in women who are family caregivers

OBJECTIVES

To examine race differences in psychosocial and psychophysiological responses to family caregiving.

DESIGN

Participants completed paper-and-pencil surveys and were exposed to a laboratory-based interpersonal challenge that included a period of rest, an interpersonal challenge, and a period of recovery.

SETTING

A university research laboratory.

PARTICIPANTS

Sixteen Caucasian and 12 African-American postmenopausal (64 +/- 10 years) women who were caregivers to a family member with dementia.

MEASURES

Psychosocial functioning included self-reported perceived stress, caregiver burden, social support, and caregiving meaning. Systolic and diastolic blood pressure (SBP, DBP) and heart rate (HR) were measured every two minutes during the rest, challenge, and recovery. Salivary cortisol was measured at rest and 15-minutes post-challenge.

RESULTS

There was a Race x Task interaction for SBP and HR but not DBP reactivity. African-American women showed greater reactivity than Caucasian women. The magnitude of this interaction was large. African-American women also reported greater caregiving from meaning than Caucasian women. In contrast, significantly more African Americans (58%) than Caucasians (14%) showed cortisol reactivity from rest to 15-minutes post-challenge.

CONCLUSIONS

The differential pattern of physiologic responses is consistent with studies outside of the caregiving literature, and suggests that caregiving may be perceived as more effortful among Caucasian women and less controllable among African-American women.

Awareness and use of community walking trails

BACKGROUND

Community trail development is an emerging strategy to increase physical activity (PA) among community residents. The purpose of this study was to assess awareness and use of trails and compare perceptions to objective data.

METHODS

A telephone survey was administered to a stratified sample of adults (N = 1,112) in a southeastern county in the United States. Respondents' home addresses and the locations of trails were entered into a GIS database. A kappa statistic was used to measure agreement between awareness and presence of trails. Differences in reported trail use patterns by sex, race, education, and PA levels were evaluated.

RESULTS

There was no agreement between the awareness and presence of trails (kappa = 0.07). Fifty-six percent of the respondents reported having trails; however, only 33% reported using the trails. Of the trail users, 42% reported being regularly active in moderate-to-vigorous PA (30+ min/day for 5+ days/week), and 51% reported being less active (P < 0.003). Among walkers (> or =30 min/day for > or =5 days/week), 49% of regular walkers and 35% of irregular walkers (< walkers) reported using the trails (P < 0.04).

CONCLUSIONS

Awareness of existing trails in this community and levels of use were low. Marketing programs should promote awareness and use of trails among older adults and irregularly active adults.

Socioeconomic status and perceptions of access and safety for physical activity

BACKGROUND

Environmental factors may play an important role on influencing physical activity (PA) behaviors.

PURPOSE

Perceptions of access and safety for PA were compared among residents who were stratified as low or high in socioeconomic status (SES).

METHODS

Residents of a U.S. southeastern county (N = 1,194, 18-96 years of age) were contacted using a random-digit-dial method and asked about neighborhood and community environmental supports for PA. A Geographic Information System (GIS) was used to identify trails, sidewalks, public recreation facilities, and violent crime incidents.

RESULTS

A cluster analysis identified 10 census tracts as low SES and 11 census tracts as high SES (median household income, owner-occupied houses). More African Americans (66.5%) than Whites (33.5%) were classified as living in low-SES areas. Respondents from low-SES areas also reported engaging in less PA based on Centers for Disease Control and Prevention and American College of Sports Medicine recommendations than respondents from high-SES areas (p <.05). Respondents from low-SES (vs. high-SES) areas reported higher perceptions of neighborhood crime, unattended dogs, unpleasantness of neighborhoods, untrustworthy neighbors, and less access to public recreation facilities (ps <.05). GIS data for presence of sidewalks, recreation facilities, and crime did not support these differences in perceptions; however, respondents from low-SES (vs. high-SES) areas had substantially fewer trails. Having and using trails in one's community predicted sufficient PA and walking for 150 min/week for low-SES respondents but not for high SES respondents (ps =.05, adjusted for covariates).

CONCLUSIONS

Having access to trails is an important environmental feature among low-SES communities and should be the focus of future community-based PA interventions.

The relationship between exposure to violence and blood pressure mechanisms

Although previous research has indicated a link between environmental stress and essential hypertension, little is known about the role of violence exposure on risk for developing essential hypertension. Violence exposure, defined as experiencing, witnessing, or hearing about violence in the home, school, or neighborhood, is a serious societal problem. Approximately 70% of inner-city youth have been victims of violent acts, and approximately 85% of these youths report having witnessed violent acts. In this review, several possible paths are proposed to explain the link between exposure to violence and cardiovascular health outcomes (eg, physiologic and psychosocial). Several contextual models are outlined, and a review of the empirical evidence suggests that chronic environmental stress (eg, violence exposure) might play a role in the development of essential hypertension. The mechanisms underlying the effects of violence exposure on blood pressure are unknown, although preliminary evidence suggests that elevated sympathetic nervous system activity may be involved. Several possible psychosocial mechanisms are outlined that might also link violence exposure to physiologic blood pressure-related mechanisms. Prevention and intervention efforts to reduce community violence are reviewed, and a call is made for encouraging further research on this critical topic.

Associations of perceived social and physical environmental supports with physical activity and walking behavior

We evaluated perceived social and environmental supports for physical activity and walking using multivariable modeling. Perceptions were obtained on a sample of households in a southeastern county. Respondents were classified according to physical activity levels and walking behaviors. Respondents who had good street lighting; trusted their neighbors; and used private recreational facilities, parks, playgrounds, and sports fields were more likely to be regularly active. Perceiving neighbors as being active, having access to sidewalks, and using malls were associated with regular walking.

Performance bounds for passive sensor arrays operating in a turbulent medium: plane-wave analysis

The performance bounds of a passive acoustic array operating in a turbulent medium with fluctuations described by a von Kármán spectrum are investigated. This treatment considers a single, monochromatic, plane-wave source at near-normal incidence. A line-of-sight propagation path is assumed. The primary interests are in calculating the Cramer-Rao lower bounds of the azimuthal and elevational angles of arrival and in observing how these bounds change with the introduction of additional unknowns, such as the propagation distance, turbulence parameters, and signal-to-noise ratio. In both two and three dimensions, it is found that for large values of the index-of-refraction variance, the Cramer-Rao lower bounds of the angles of arrival increase significantly at large values of the normalized propagation distance. For small values of the index-of-refraction variance and normalized propagation distance, the signal-to-noise ratio is found to be the limiting factor. In the two-dimensional treatment, it is found that the estimate of the angle of arrival will decouple from the estimates of the other parameters with the appropriate choice of array geometry. In three dimensions, again with an appropriate choice of array geometry, the estimates of the azimuth and elevation will decouple from the estimates of the other parameters, but due to the constraints of the model, will remain coupled to one another.

Motivational versus social cognitive interventions for promoting fruit and vegetable intake and physical activity in African American adolescents

Strategic self-presentation (motivational intervention [MI]) is a theoretical approach that is distinct from social cognitive theory (SCT). Specifically, strategic self-presentation involves increasing motivation by creating cognitive dissonance and inducing shifts in self-concept by generating positive coping strategies during a videotaped session. Fifty-three healthy African American adolescents were randomized to a SCT+MI, SCT-only, or an education-only group for increasing fruit and vegetable (F&V) intake and physical activity. The SCT+MI and SCT-only groups received a 12-week SCT program. Students in the SCT+MI group also participated in a strategic self-presentation videotape session. Participants completed 3-day food records, completed measures of self-concept and self-efficacy, and wore an activity monitor for 4 days at pre- and posttreatment. Both the SCT+MI (2.6 +/- 1.4 vs. 5.7 +/- 2.2, p < .05) and the SCT-only (2.5 +/- 1.2 vs. 4.8 +/- 2.4, p < .05) groups showed greater increases in F&V intake from pre- to posttreatment as compared with the education-only group (2.3 +/- 1.0, vs. 3.3 +/- 2.1, p > .05). There were no significant time or group effects for any of the physical activity measures. Correlation analyses revealed that only the SCT+MI group showed that dietary self-concept (r = .58, r = .67, p < .05) and dietary self-efficacy (r = .65, r = .85, p < .05) were significantly correlated with posttreatment F&V intake and change in F&V intake, respectively. These findings suggest that the change in F&V intake in the SCT+MI group resulted from strategic self-presentation, which induced positive shifts in self-concept and self-efficacy.

Violence exposure, catecholamine excretion, and blood pressure nondipping status in African American male versus female adolescents

OBJECTIVE

Nondipping status (<10% decrease in blood pressure [BP] from awake to asleep) has been associated with end-organ disease (stroke and left ventricular hypertrophy) in adults. Nondipping status has also been observed in 30% of healthy African American adolescents, but little is known about the correlates of nondipping status in adolescents. This study examined the relationship between violence exposure, catecholamine excretion, and BP nondipping status in 56 healthy African American adolescents (27 boys, 29 girls; ages 11-18 years).

METHODS

Participants completed the Survey of Exposure to Community Violence, wore an ambulatory BP monitor and provided one timed day and night urine collection for determination of epinephrine and norepinephrine excretion.

RESULTS

Boys had higher daytime epinephrine (5.1 +/- 3.3 vs. 2.6 +/- 2.3 ng/min, p < .001) and norepinephrine excretion (29.2 +/- 25.1 vs. 16.5 +/- 14.9 ng/min, p < .05) and showed a greater prevalence of mean BP nondipping status than girls (37% vs. 10%, p < .03). Mean BP nondipping status was positively associated with victimization (r = 0.42, p < .0001). Regression analyses indicated a significant interaction between hearing about violence and sex for predicting daytime epinephrine (p < .02), with male nondippers showing a stronger positive association (partial correlation = 0.59, p < .05) than females (partial correlation = 0.03, p = NS). Logistic regressions also demonstrated a significant interaction between hearing about violence and sex for predicting mean BP dipping status, with male nondippers reporting the greatest exposure.

CONCLUSIONS

Mean BP nondipping was associated with victimization in both boys and girls. Boys who reported higher levels of hearing about violence showed greater daytime epinephrine excretion and were more likely to be classified as nondippers.

The role of gender and family support on dietary compliance in an African American adolescent hypertension prevention study

Social support experiences vary markedly across gender groups, and little is known about the role of social support in promoting healthy dietary compliance in African American adolescents who are at increased risk for developing hypertension. This study examined the relation between gender, dietary social support, and compliance to a low sodium diet. Casual blood pressures were also examined in relation to dietary compliance and gender One hundred eighty-four healthy African American adolescents (83 boys, 101 girls) participated in an intensive 5-day low sodium diet (50 mEq/24 hr) as part of a hypertension prevention program. Emotional dietary social support from family members and friends was measured at baseline. Compliance was defined as urinary sodium excretion of < or = 50 mEq/24 hr at postsodium restriction. The results indicated a significant Gender x Compliance effect for positive family support (p < .05). Girls who were compliant reported higher levels of dietary support from family members (19.2 +/- 7.8) than boys who were compliant (16.9 +/- 7.0). In contrast, boys who were compliant reported lower levels of dietary support from family members (16.9 +/- 7.0) than boys who were not compliant (20.2 +/- 7.5). Systolic blood pressure showed a trend toward decreasing in compliant participants (104.4 +/- 8.4 vs. 101.7 +/- 8.0, mm Hg, p < .06), but the effect diminished when Quetelet Index (kg/m2) was controlled for in the analyses (p < .12). These results suggest that higher levels of emotional dietary support from family members are associated with better adherence to short-term sodium restriction for African American girls as compared to boys. Further research is needed to determine the long-term impact of social support on sodium restriction in adolescent populations.

Sound propagation in a turbulent atmosphere near the ground: a parabolic equation approach

The interference of the direct wave from the point source to the receiver and the wave reflected from the impedance ground in a turbulent atmosphere is studied. A parabolic equation approach for calculating the sound pressure p at the receiver is formulated. Then, the parabolic equation is solved by the Rytov method yielding expressions for the complex phases of direct and ground-reflected waves. Using these expressions, a formula for the mean squared sound pressure [absolute value(p)2] is derived for the case of anisotropic spectra of temperature and wind velocity fluctuations. This formula contains the "coherence factor," which characterizes the coherence between direct and ground-reflected waves. It is shown that the coherence factor is equal to the normalized coherence function of a spherical sound wave for line-of-sight propagation. For the case of isotropic turbulence, this result allows one to obtain analytical formulas for [absolute value(p)2] for the Kolmogorov, Gaussian, and von Karman spectra of temperature and wind velocity fluctuations. Using these formulas, the effects of temperature and wind velocity fluctuations, and the effects of different spectra of these fluctuations on the mean squared sound pressure, are numerically studied. Also the effect of turbulent anisotropy on the interference of direct and ground reflected waves is numerically studied. Finally, it is shown that the mean squared sound pressure [absolute value(p)2] calculated for the von Karman spectrum of temperature fluctuations agrees well with experimental data obtained in a laboratory experiment.

Atmospheric scattering for varying degrees of saturation and turbulent intermittency

Atmospheric turbulence is inherently inhomogeneous and intermittent. Short periods of high activity are embedded in longer periods of relative calm. Local spatial and temporal changes in sound speed associated with this intermittency increase the likelihood of measuring large values of scattered acoustic signals. Previous work successfully predicted the probability density functions (pdf's) of fully saturated, scattered signals measured within an acoustic shadow zone [Wilson et al., J. Acoust. Soc. Am. 99, 3393-3400 (1996)]. The more general case of incompletely saturated scattering is considered in this paper; using the Rice-Nagakami distribution a theory is developed. The predicted intensity pdf has two free parameters: one to describe the degree of intermittency and a second for the degree of saturation. For validation purposes, outdoor propagation measurements were made over a flat, hard ground at ranges of 146-283 m and at frequencies of 50-540 Hz. The saturation parameter was determined from the acoustic data and also estimated from the turbulence conditions. The degree of saturation increased with frequency, and measured intensity pdf's were found to be in excellent agreement with the theory.

Statistical moments of the sound field propagating in a random, refractive medium near an impedance boundary

Propagation of a monochromatic sound field in a refractive and turbulent medium near an impedance boundary is considered. Starting from the parabolic equation for a moving medium and using the Markov approximation, a closed equation for the statistical moments of arbitrary order of the sound-pressure field is derived. Numerical methods for directly solving the first- and second-moment versions of this equation are formulated. The first-moment formulation is very similar to parabolic equations (PEs) that are now widely used to calculate sound fields for particular realizations of a random medium. The second-moment formulation involves a large, fringed tridiagonal matrix, which is solved using iterative refinement and Cholesky factorization. The solution is computationally intensive and currently restricted to low frequencies. As an example, the first and second moments are directly calculated for upwind and downwind propagation of a sound wave through a turbulent atmosphere. For these cases, predictions from the second-moment PE were statistically indistinguishable from the result of 40 random trials calculated with a standard Crank-Nicholson PE, although the second-moment PE yielded smoother results due to its ensemble-average nature.

The crystal structure of the GCY1 protein from S. cerevisiae suggests a divergent aldo-keto reductase catalytic mechanism

The crystal structure of the GCY1 gene product from Saccharomyces cerevisiae has been determined to 2.5 A and is being refined. The model includes two protein molecules, one apo and one holo, per asymmetric unit. Examination of the model reveals that the active site surface is somewhat flat when compared with the other aldo-keto reductase structures, possibly accommodating larger substrates. The K(m) for NADPH (28.5 microM) is higher than that seen for other family members. This can be explained structurally by the lack of the 'safety belt' of residues seen in other aldo-keto reductases with higher affinity for NADPH. Catalysis also differs from the other aldo-keto reductases. The tyrosine that acts as an acid in the reduction reaction is flipped out of the catalytic pocket. This implies that the protein must either undergo a conformational change before catalysis can take place or that there is an alternate acid moiety.

A turbulence spectral model for sound propagation in the atmosphere that incorporates shear and buoyancy forcings

A three-dimensional model for turbulent velocity fluctuations in the atmospheric boundary layer is developed and used to calculate scattering of sound. The model, which is based on von Karman's spectrum, incorporates separate contributions from shear- and buoyancy-forced turbulence. New equations are derived from the model that predict the strength and diffraction parameters for scattering of sound as a function of height from the ground and atmospheric conditions. The need is demonstrated for retaining two distinct scattering length scales, one associated with scattering strength and the other with diffraction. These length scales are height dependent and vary substantially with the relative proportions of shear and buoyancy forcing. The turbulence model predicts that for forward-scattered waves the phase variance is much larger than the log-amplitude variance, a behavior borne out by experimental data. A new method for synthesizing random fields, based on empirical orthogonal functions, is developed to accommodate the height dependence of the turbulence model. The method is applied to numerical calculations of scattering into an acoustic shadow zone, yielding good agreement with previous measurements.

Crystallization and aldo-keto reductase activity of Gcy1p from Saccharomyces cerevisiae

Crystallization and preliminary X-ray diffraction studies of Gcy1p, an aldo-keto reductase from Saccharomyces cerevisiae, have been performed. Both the wild type and a double-mutant form of Gcy1p were crystallized using the hanging-drop method at 298 K; however, only the double-mutant form has so far yielded crystals suitable for X-ray diffraction analysis. These crystals belonged to the primitive monoclinic space group P2(1), with unit-cell parameters a = 50.94, b = 65.64, c = 86.23 A, beta = 92.64 degrees. Diffraction data were collected to 2.5 A. Assuming two 35 kDa subunits in the asymmetric unit yielded a V(m) of 2.06 A(3) Da(-1). Additionally, a kinetic study performed by measuring the rate of oxidation of NADPH in the presence of several substrates indicates that both wild-type and double-mutant proteins are enzymes possessing NADPH-dependent reductase activity.

The influence of gender and emotional versus instrumental support on cardiovascular reactivity in African-American adolescents

Research suggests that females seek out, prefer, and are more receptive to emotional support (encouragement), and that males seek out, prefer, and are more receptive to instrumental support (problem-solving). Thus, we hypothesized that boys would show lower blood pressure (BP) reactivity in response to instrumental than emotional or no support, and that girls would show lower BP reactivity in response to emotional than instrumental or no support. Forty-eight healthy African-American adolescents (50% males) participated in a role play conflict task and were randomized to receive either emotional, instrumental, or no support (presence only) from a confederate. Boys showed lower systolic blood pressure (SBP) reactivity in the instrumental than in the emotional or no support conditions and lower recovery SBP as compared to boys in the emotional or no support conditions. A similar pattern of results was demonstrated for diastolic blood pressure (DBP) reactivity. Girls, however, did not demonstrate lower BP reactivity in response to emotional as compared to instrumental support. These findings suggest that instrumental and emotional support differentially influence cardiovascular (CV) reactivity in African-American boys versus girls.

Socioeconomic status and blood pressure reactivity in healthy black adolescents

Adolescents in low-socioeconomic-status environments are more susceptible to illnesses, such as hypertension and cardiovascular diseases. This study examined the influence of both neighborhood- and family-level socioeconomic status (SES) on blood pressure (BP) reactivity in a healthy sample of 76 black adolescents. It was hypothesized that a higher level of parental education and/or income would reduce the elevated BP reactivity associated with living in poorer neighborhoods. Census-derived data were obtained using each participant's address. Neighborhood level of SES was based on percentage of households below the poverty line, female-headed households, owner-occupied housing, percentage vacant housing, and average number of persons per household. Family level of SES was based on self-reported level of parental education and annual family income. Adolescents participated in a competitive video game to establish their BP reactivity scores. As predicted, adolescents who lived in poorer neighborhoods had lower diastolic BPs if their parents were more (versus less) educated (P<0.05; 7+/-8 versus 13+/-6 mm Hg). Adolescents who lived in poorer neighborhoods also had significantly lower diastolic BP reactivity (P<0.05) if their family had a higher (versus lower) annual income (7+/-7 versus 12+/-8 mm Hg). These data are the first to demonstrate the buffering effect of family SES on the negative health consequences of living in low-SES neighborhoods in healthy black adolescents.

The prevalence of salt sensitivity in an African-American adolescent population

This study examined the prevalence of salt-sensitivity (SS) in 140 healthy African-American adolescents. SS was defined as an increase in mean blood pressure > or =5 mm Hg from a 5-day low salt (Na+) diet (50 mmol/24 hr) to a 10-day high Na+ diet (150 mmol/24 hr NaCl supplement); remaining subjects were classified as salt-resistant (SR). Dietary compliance was defined as Na+ excretion < or =50 mmol/24 hr for the low Na+ diet and > or =165 mmol/24 hr for the high NaCl supplement diet. 31 (22%) subjects were classified as SS and 109 (78%) as SR. There were no significant differences between SS and SR subjects on baseline characteristics, family history of hypertension, or on resting blood pressure or heart rate measures. As expected, SS subjects showed a greater increase in mean, systolic, and diastolic blood pressures (P<.001 for all) than SR subjects in response to the high NaCl supplement. There was a greater increase in weight (P<.01) and Quetelet Index (P<.05) for SS than SR subjects in response to Na+ loading. These results are the first to show that SS is prevalent in a subgroup of healthy African-American adolescents.

Effects of potassium on blood pressure in salt-sensitive and salt-resistant black adolescents

This study examined the effects of increasing dietary potassium on ambulatory blood pressure nondipping status (<10% decrease in blood pressure from awake to asleep) and cardiovascular reactivity in salt-sensitive and salt-resistant black adolescents. A sample of 58 normotensive (blood pressure, 101/57+/-9/4 mm Hg) black adolescents (aged 13 to 16 years) participated in a 5-day low sodium diet (50 mmol/24 h) followed by a 10-day high sodium diet (150 mmol/24 h NaCl supplement) to determine salt-sensitivity status. Participants showed a significant increase in urinary sodium excretion (24+/-19 to 224+/-65 mmol/24 h) and were identified as salt-sensitive if their mean blood pressure increase was >/=5 mm Hg from the low to high sodium diet. Sixteen salt-sensitive and 42 salt-resistant subjects were then randomly assigned to either a 3-week high potassium diet (80 mmol/24 h) or usual diet control group. Urinary potassium excretion significantly increased in the treatment group (35+/-7 to 57+/-21 mmol/24 h). At baseline, a significantly greater percentage of salt-sensitive (44%) compared with salt-resistant (7%) subjects were nondippers on the basis of diastolic blood pressure classifications (P<0.04). After the dietary intervention, all of the salt-sensitive subjects in the high potassium group achieved dipper status as a result of a drop in nocturnal diastolic blood pressure (daytime, 69 versus 67 mm Hg; nighttime, 69 versus 57 mm Hg). No significant group differences in cardiovascular reactivity were observed. These results suggest that a positive relationship between dietary potassium intake and blood pressure modulation can still exist even when daytime blood pressure is unchanged by a high potassium diet.

Ambulatory blood pressure nondipping status in salt-sensitive and salt-resistant black adolescents

This study examined the relationship between salt sensitivity and ambulatory blood pressure in 53 healthy black adolescents. Salt sensitivity was defined as an increase in mean blood pressure greater than or exceeding 5 mm Hg from a 5-day low-salt diet (50 mmol/24 h) to a 10-day high-salt diet (150 mmol/24 h NaCl supplement). Sixteen subjects were salt sensitive and 37 subjects were salt resistant (showed < 5 mm Hg increase in mean blood pressure). Subjects were classified as dippers (> or =10% decrease in blood pressure from awake to asleep) based on their 24-h ambulatory blood pressure values. Nondippers showed higher systolic, diastolic, and mean asleep blood pressures than dippers (P < .05 for all). Salt-sensitive subjects showed greater daytime diastolic and mean blood pressures than salt-resistant subjects (P < .05 for both). A significantly greater percentage of nondippers were salt sensitive, compared with salt resistant for diastolic blood pressure (P < .001) and mean blood pressure (P < .05). For both of these blood pressure measures, 50% of the salt-sensitive subjects had a nondipping status, compared with only 5.4% of the salt-resistant subjects for diastolic blood pressure, and 18.9% of the salt-resistant subjects for mean blood pressure. These results are the first to indicate that salt sensitivity is associated with nondipper blood pressure status in a black normotensive adolescent population.

Symptomatic age-related macular degeneration in Asian patients

PURPOSE

To characterize retinal and fluorescein angiographic findings of Asian patients with symptoms secondary to age-related macular degeneration (ARMD).

METHODS

We retrospectively reviewed 453 consecutive medical records corresponding to fluorescein angiograms performed between November 1992 and November 1995 to identify Asian patients with symptomatic ARMD. Presenting visual symptoms, best-corrected Snellen visual acuities, and retinal examination findings were determined from the medical records. Fundus photos and fluorescein angiograms were reviewed.

RESULTS

There were 26 symptomatic eyes in 19 Asian patients with a median age of 73 years. Presenting visual symptoms included decreased visual acuity (19 eyes), metamorphopsia (5 eyes), or scotoma (2 eyes). Retinal findings included occult choroidal neovascularization (CNV) in 5 (19%) eyes, serous pigment epithelial detachment (PED) in 8 (31%) eyes, PED with CNV in 5 (19%) eyes, drusen in 5 (19%) eyes, retinal pigment epithelial atrophy in 1 (4%) eye, vitreous hemorrhage in 1 (4%) eye, and a disciform scar in 1 (4%) eye.

CONCLUSION

In this cohort of Asian patients with ARMD, the majority of symptomatic eyes had either CNV (46%) or serous PED (31%).

Structural features of the aldose reductase and aldehyde reductase inhibitor-binding sites

The three-dimensional structures of aldose reductase and aldehyde reductase, members of the aldo-keto reductase superfamily, are composed of similar alpha/beta TIM-barrels. However, examination of the structures reveals that the inhibitor-binding site of aldose reductase differs from that of aldehyde reductase due to the participation of non-conserved residues in its formation. This information will be useful in the design of inhibitors to prevent or delay diabetic retinopathy. A review of the structures of the inhibitor-binding sites is presented.

Gynecologic cancers metastatic to the breast

BACKGROUND

We report a series of gynecologic cancers metastatic to the breast, illustrating the diagnostic and prognostic implications of this rare event.

STUDY DESIGN

By reviewing the gynecologic oncology data base, we identified 10 women with gynecologic cancer metastatic to the breast who were treated at Indiana University School of Medicine between August 1978 and February 1995. Medical records were reviewed for pertinent data concerning the presentation, evaluation, and treatment of the primary gynecologic malignancy and the metastatic breast tumor.

RESULTS

The mean patient age was 56.8 years (range, 30-80 years). The most common gynecologic malignancy was ovarian cancer (five patients), followed by cervical cancer (two patients) and cancers of the vagina, endometrium, or peritoneum (one patient each). A palpable solitary breast mass was found in 8 of 10 patients (80%), and the upper outer quadrant of the breast was the most common site of tumor involvement. One woman presented with examination findings resembling inflammatory breast cancer, and one patient presented with multiple firm subcutaneous nodules. Despite further treatment, which in all cases consisted of systemic chemotherapy, 83% of the patients died with a breast metastasis within 1 year of presentation.

CONCLUSIONS

Secondary breast malignancy should be suspected in any patient with a breast tumor and a known history of gynecologic cancer. A breast metastasis implies widespread tumor dissemination and a poor prognosis. Radical breast surgery should be avoided.

The role of divalent cations in structure and function of murine adenosine deaminase

For murine adenosine deaminase, we have determined that a single zinc or cobalt cofactor bound in a high affinity site is required for catalytic function while metal ions bound at an additional site(s) inhibit the enzyme. A catalytically inactive apoenzyme of murine adenosine deaminase was produced by dialysis in the presence of specific zinc chelators in an acidic buffer. This represents the first production of the apoenzyme and demonstrates a rigorous method for removing the occult cofactor. Restoration to the holoenzyme is achieved with stoichiometric amounts of either Zn2+ or Co2+ yielding at least 95% of initial activity. Far UV CD and fluorescence spectra are the same for both the apo- and holoenzyme, providing evidence that removal of the cofactor does not alter secondary or tertiary structure. The substrate binding site remains functional as determined by similar quenching measured by tryptophan fluorescence of apo- or holoenzyme upon mixing with the transition state analog, deoxycoformycin. Excess levels of adenosine or N6- methyladenosine incubated with the apoenzyme prior to the addition of metal prevent restoration, suggesting that the cofactor adds through the substrate binding cleft. The cations Ca2+, Cd2+, Cr2+, Cu+, Cu2+, Mn2+, Fe2+, Fe3+, Pb2+, or Mg2+ did not restore adenosine deaminase activity to the apoenzyme. Mn2+, Cu2+, and Zn2+ were found to be competitive inhibitors of the holoenzyme with respect to substrate and Cd2+ and Co2+ were noncompetitive inhibitors. Weak inhibition (Ki > or = 1000 microM) was noted for Ca2+, Fe2+, and Fe3+.

Specifically targeted modification of human aldose reductase by physiological disulfides

Aldose reductase is inactivated by physiological disulfides such as GSSG and cystine. To study the mechanism of disulfide-induced enzyme inactivation, we examined the rate and extent of enzyme inactivation using wild-type human aldose reductase and mutants containing cysteine-to-serine substitutions at positions 80 (C80S), 298 (C298S), and 303 (C303S). The wild-type, C80S, and C303S enzymes lost >80% activity following incubation with GSSG, whereas the C298S mutant was not affected. Loss of activity correlated with enzyme thiolation. The binary enzyme-NADP+ complex was less susceptible to enzyme thiolation than the apoenzyme. These results suggest that thiolation of human aldose reductase occurs predominantly at Cys-298. Energy minimization of a hypothetical enzyme complex modified by glutathione at Cys-298 revealed that the glycyl carboxylate of glutathione may participate in a charged interaction with His-110 in a manner strikingly similar to that involving the carboxylate group of the potent aldose reductase inhibitor Zopolrestat. In contrast to what was observed with GSSG and cystine, cystamine inactivated the wild-type enzyme as well as all three cysteine mutants. This suggests that cystamine-induced inactivation of aldose reductase does not involve modification of cysteines exclusively at position 80, 298, or 303.

Site-directed mutagenesis of histidine 238 in mouse adenosine deaminase: substitution of histidine 238 does not impede hydroxylate formation

His 238, a conserved amino acid located in hydrogen-bonding distance from C-6 of the substrate in the active site of murine adenosine deaminase (mADA) and postulated to play an important role in catalysis, was altered into an alanine, a glutamate, and an arginine using site-directed mutagenesis. The Ala and Glu substitutions did not result in changes of the secondary or tertiary structure, while the Arg mutation caused local perturbations in tertiary structure and quenched the emission of one or more enzyme tryptophans. Neither the Glu or Arg mutations affected substrate binding affinity. By contrast, the Ala mutation enhanced substrate and inhibitor binding by 20-fold. The most inactive of the mutants, Glu 238, had a kcat/K(m) 4 x 10(-6) lower than the wild-type value, suggesting that a positive charge on His 238 is important for proper catalytic function. The Ala 238 mutant was the most active ADA, with a kcat/K(m) 2 x 10(-3) lower than the wild-type value. NMR spectroscopy and crystallography revealed that this mutant is able to catalyze hydration of purine riboside, a ground-state analog of the reaction. These results collectively show that His 238 is not required for formation of the hydroxylate used in the deamination and may instead have an important electrostatic role.

Variability in salt sensitivity classifications in black male versus female adolescents

Salt sensitivity (changes in blood pressure in response to alterations in salt intake) may be a risk factor for hypertension. In the present study, we examined the prevalence of salt sensitivity based on two different classifications in healthy black male and female adolescents (aged 13 to 16 years). A total of 135 black adolescents participated in a 50 mmol/24 h low sodium diet for 5 days and a 150 mmol/24 h NaCl supplement for 10 days. Dietary compliance was defined as sodium excretion less than or equal to 50 mmol/24 h for the low sodium diet and greater than or equal to 165 mmol/24h for the high NaCl supplement. Salt sensitivity was defined by two classifications: (1) as a decrease in mean blood pressure greater than or equal to 5 mm Hg from baseline to the low sodium diet, and (2) as an increase in mean blood pressure greater than or equal to 5 mm Hg from the low sodium diet to the high NaCl supplement. With classification 1, 14% of boys were identified as salt sensitive compared with 22% of girls. With classification 2, however, 31% of boys were identified as salt sensitive compared with 18% of girls. Analyses based on changes in systolic pressure demonstrated similar findings across sex, although overall classifications based on systolic pressure yielded a greater percentage of salt-sensitive subjects. These sex differences in classification patterns were not due to differences in other important variables, such as changes in sodium excretion, potassium excretion, or Quetelet index. These results suggest that the prevalence of salt sensitivity differs by sex depending on the type of protocol used for the classification of salt sensitivity in a black pediatric population.

Probing the functional role of two conserved active site aspartates in mouse adenosine deaminase

Two adjacent aspartates, Asp 295 and Asp 296, playing major roles in the reaction catalyzed by mouse adenosine deaminase (mADA) were altered using site-directed mutagenesis. These mutants were expressed and purified from an ADA-deficient bacterial strain and characterized. Circular dichroism spectroscopy shows the mutants to have unperturbed secondary structure. Their zinc content compares well to that of wild-type enzyme. Changing Asp 295 to a glutamate decreases the kcat but does not alter the Km for adenosine, confirming the importance of this residue in the catalytic process and its minimal role in substrate binding. The crystal structure of the D295E mutant reveals a displacement of the catalytic water from the active site due to the longer glutamate side chain, resulting in the mutant's inability to turn over the substrate. In contrast, Asp 296 mutants exhibit markedly increased Km values, establishing this residue's critical role in substrate binding. The Asp 296->Ala mutation causes a 70-fold increase in the Km for adenosine and retains 0.001% of the wild-type kcat/Km value, whereas the ASP 296->Asn mutant has a 10-fold higher Km and retains 1% of the wild-type kcat/Km value. The structure of the D296A mutant shows that the impaired binding of substrate is caused by the loss of a single hydrogen bond between a carboxylate oxygen and N7 of the purine ring. These results and others discussed below are in agreement with the postulated role of the adjacent aspartates in the catalytic mechanism for mADA.

Theoretical study of inhibition of adenosine deaminase by (8R)-coformycin and (8R)-deoxycoformycin

Molecular dynamics and free energy simulations were performed to examine the binding of (8R)-deoxycoformycin and (8R)-coformycin to adenosine deaminase. The two inhibitors differ only at the 2' position of the sugar ring; the sugar moiety of conformycin is ribose, while it is deoxyribose for deoxycoformycin. The 100 ps molecular dynamics trajectories reveal that Asp 19 and His 17 interact strongly with the 5' hydroxyl group of the sugar moiety of both inhibitors and appear to play an important role in binding the sugar. The 2' and 3' groups of the sugars are near the protein-water interface and can be stabilized by either protein residues or water. The flexibility of the residues at the opening of the active site helps to explain the modest difference in binding of the two inhibitors and how substrates/inhibitors can enter an otherwise inaccessible binding site.