Lack of PI 3-kinase isoform p110alpha impairs SMC differentiation and proliferation and promotes aortic aneurysm formation

Background

Proliferation and phenotypic modulation of vascular smooth muscle cells (SMCs) significantly contribute to the functionality of the aortic wall. Dysregulation of underlying signal transduction pathways impairs the vessel wall structure and promote the development and progression of abdominal aortic aneurysms (AAA). The PI 3-kinase (PI3K) isoform p110α is activated downstream of receptor tyrosine kinases (RTKs) and represents the most relevant PI3K isoform in SMCs.

Aim

This project follows the hypothesis that p110α deficiency impairs proliferation and phenotypic modulation of SMCs as well as the structure of the extracellular matrix (ECM) and therefore promotes the development and progression of AAA. It was investigated how p110α deficiency affects the plasticity of SMCs, the production and structure of ECM components, and the formation of AAA.

Methods and results

Western blot analyses showed that SMCs isolated from smooth muscle specific p110α−/− (sm-p110α−/−) mice were characterized by decreased expression of the differentiation markers sm-α-actin, calponin and sm-MHC. Mechanistically, phosphorylation of key modulators of the SMC phenotype – AKT1, AKT2, FOXO1, -3 and -4 as well as GSK3β – was impaired in p110α−/− SMCs after RTK stimulation. These findings indicate that phenotypic modulation of p110α−/− SMCs is restricted. In addition, protein expression of elastin and fibrillin was reduced in p110α−/− SMCs. In silico analysis (MatLab macro CT-FIRE and Curvalign) of the ECM produced by SMCs in vitro revealed a significantly reduced elastin fiber length and width in p110α−/− SMCs compared to fibers produced by WT SMCs (p<0.05). Consistently, aortas from sm-p110α−/− mice showed a significantly higher number of elastic fiber breaks specifically in the thoracic section than WT controls (289±31 mmm–2 versus 190±9 mmm–2, n=5, p=0.015). Aortic aneurysms in sm-p110α−/− mice and wild-type littermates were analyzed using the established porcine pancreatic elastase (PPE) model. PPE was perfused into the infrarenal aorta to induce AAA formation. Ultrasound examination of the aorta revealed an enlarged aortic diameter in all PPE-treated mice. However, the increase in aortic diameter in sm-p110α−/− mice (70.16±10.82% mm, n=9) was significant more pronounced compared to wild-type animals (42.44±5.99%, n=10) (p<0.05). Three days after PPE perfusion, the number of elastic fiber breaks was significantly increased, and amount of proliferating SMCs were decreased in the infrarenal aorta of sm-p110α−/− mice compared to WT controls.

Conclusion

p110α deficiency in SMCs impairs aortic wall structure and promotes the development and progression of aortic aneurysms. Mechanistically, p110α activity maintains a differentiated SMC phenotype as well as the expression and assembly of ECM components. These data identify p110α signaling as a modifiable target for preventive and therapeutic strategies for aortic aneurysms.

Funding Acknowledgement

Type of funding sources: Public grant(s) – National budget only. Main funding source(s): Deutsche Forschungsgemeinschaft

The role of motivation on physical activity and screen time behaviors among parent-adolescent dyads: The FLASHE study

Behavioral theories inform the development of lifestyle interventions to address low participation in physical activity (PA); however, relatively little is known about the value of self-determination theory (SDT) for explaining screen time (ST) behaviors or in extending SDT into a dyadic context. Actor-partner (i.e., parent-adolescent) interdependence models (APIMs) allow for examination of these interpersonal relationships. The purpose of this study was to examine PA and ST among parent-adolescent dyads using the cross-sectional Family Life, Activity, Sun, Health, and Eating (FLASHE) Study. Parent-adolescent dyads provided responses to online surveys addressing PA (n = 1177 dyads) and ST (n = 1489 dyads) behaviors. We examined the influence of SDT-based constructs (perceived competence and motivation) on PA and ST behaviors. Structural equations were used to estimate APIMs in STATA 15.1. Full models provided a good fit to the data. For both PA and ST, perceived competence was more strongly associated with motivation among adolescents compared with parents (PA: β = 0.72 vs. 0.58, ST: β = 0.34 vs. 0.22, p's < 0.001). Parental motivation was associated with parental PA and both adolescent motivation for PA and ST (p's < 0.001). Parental motivation was not associated with adolescent ST-behavior. Adolescent motivation was only associated with parent motivation for PA. In the FLASHE study, SDT constructs extend acceptably to the dyadic setting, with PA models providing a slightly better fit to the data than ST models. Longitudinal studies that target perceived competence and the self-regulation of motivation in parents and their adolescents are a next logical step to understanding both PA and ST behaviors.

Changes in Physical Activity and Television Viewing From Pre-pregnancy Through Postpartum Among a Socioeconomically Disadvantaged Perinatal Adolescent Population

STUDY OBJECTIVE

Adolescent pregnancy contributes to accelerated trajectories of adiposity and cardiometabolic diseases. Two potentially low-cost prevention strategies include promoting physical activity (PA) and limiting television (TV) viewing. Few studies have explored these behavior patterns in perinatal adolescents. This study sought to characterize PA and TV viewing in a socioeconomically disadvantaged perinatal adolescent population.

DESIGN, SETTING, PARTICIPANTS, AND INTERVENTIONS

A cross-sectional, retrospective, 10-item survey was used to explore behavior patterns in 79 predominantly Black (86%) postpartum adolescents.

MAIN OUTCOME MEASURES

Outcomes included self-reported changes in PA from pre-pregnancy through pregnancy, and 7-day recall of PA and TV viewing in postpartum.

RESULTS

The majority of adolescents (66%) reported being active on ≥3 days/week in pre-pregnancy; however, many reported low PA (≤2 days/wk) in their first (59%), second (66%), and third (54%) trimesters. Adolescents who reported being active on ≥5 days/wk in pre-pregnancy (19%) experienced first trimester PA decline, which subsequently plateaued. This group remained the most active throughout pregnancy. In postpartum, over half (54%) of all adolescents reported low PA and irrespective of PA, spent considerable time watching TV (median = 1680.0 minutes, inerquartile range = 2940).

CONCLUSION

Interventions promoting PA coupled with reducing TV viewing during pregnancy and in postpartum may benefit perinatal adolescents. The findings from this study suggest that PA history is a predictor of gestational PA, and low PA and high TV viewing in postpartum underscore the need for behavioral intervention. Conducting a brief assessment of PA history in early gestation may offer important insight.

Implementation of a Community Walking Program (Walk On!) for Functionally-Limited Older Adults

BACKGROUND

Walking interventions improve physical function, reduce fall risk, and prevent mobility disability-even in those with compromised walking ability. However, most prior studies have been conducted in controlled research settings, with no dissemination of an evidence-based walking program for older adults who have mobility limitations and/or are socially isolated.

OBJECTIVES

This study reports data on the feasibility and acceptability of a community-based walking program (Walk On!) for older adults who are functionally limited, and assesses changes in physical function among attendees. The program sessions focused on long-distance walking, and took place for one-hour, for two days/week, and for 12 weeks at a time.

DESIGN

Pilot implementation study.

SETTING

Local church in Winston-Salem, NC.

PARTICIPANTS

49 program participants; Measurements: Physical function battery and satisfaction survey data, as well as formative evaluation data from six attendees of a focus group, are reported.

RESULTS

The majority of the participants were >75 years (71%), female (65%), and presented with low levels of physical function (usual gait speed=0.79±0.16; 30.6% used an assistive device). Satisfaction with the program was high (100% would recommend it to others) and focus group results were overwhelmingly positive. Mean attendance to scheduled sessions was 77%±21%, and 63% of participants attended at least 75% of scheduled sessions (n=8 attended 100%). On average, participants improved their 6-min walk distance by 8.9%, their SPPB score by 15.4%, their timed-up-go time by 9.0%, and their usual gait speed by 11.4%.

CONCLUSION

The results of the initial evaluation of Walk On! show high feasibility and acceptability of the program, as well as efficacy for improving physical function. Further research is needed to evaluate a delivery method for wider implementation of the program and to definitively test its effectiveness for improving function and other health benefits.

APOL1 Long-term Kidney Transplantation Outcomes Network (APOLLO): Design and Rationale

INTRODUCTION

Much of the higher risk for end-stage kidney disease (ESKD) in African American individuals relates to ancestry-specific variation in the apolipoprotein L1 gene (APOL1). Relative to kidneys from European American deceased-donors, kidneys from African American deceased-donors have shorter allograft survival and African American living-kidney donors more often develop ESKD. The National Institutes of Health (NIH)-sponsored APOL1 Long-term Kidney Transplantation Outcomes Network (APOLLO) is prospectively assessing kidney allograft survival from donors with recent African ancestry based on donor and recipient APOL1 genotypes.

METHODS

APOLLO will evaluate outcomes from 2614 deceased kidney donor-recipient pairs, as well as additional living-kidney donor-recipient pairs and unpaired deceased-donor kidneys.

RESULTS

The United Network for Organ Sharing (UNOS), Association of Organ Procurement Organizations, American Society of Transplantation, American Society for Histocompatibility and Immunogenetics, and nearly all U.S. kidney transplant programs, organ procurement organizations (OPOs), and histocompatibility laboratories are participating in this observational study. APOLLO employs a central institutional review board (cIRB) and maintains voluntary partnerships with OPOs and histocompatibility laboratories. A Community Advisory Council composed of African American individuals with a personal or family history of kidney disease has advised the NIH Project Office and Steering Committee since inception. UNOS is providing data for outcome analyses.

CONCLUSION

This article describes unique aspects of the protocol, design, and performance of APOLLO. Results will guide use of APOL1 genotypic data to improve the assessment of quality in deceased-donor kidneys and could increase numbers of transplanted kidneys, reduce rates of discard, and improve the safety of living-kidney donation.

Ensuring respect for persons in COMPASS: a cluster randomised pragmatic clinical trial

Cluster randomised clinical trials present unique challenges in meeting ethical obligations to those who are treated at a randomised site. Obtaining informed consent for research within the context of clinical care is one such challenge. In order to solve this problem it is important that an informed consent process be effective and efficient, and that it does not impede the research or the healthcare. The innovative approach to informed consent employed in the COMPASS study demonstrates the feasibility of upholding ethical standards without imposing undue burden on clinical workflows, staff members or patients who may participate in the research by virtue of their presence in a cluster randomised facility. The COMPASS study included 40 randomised sites and compared the effectiveness of a postacute stroke intervention with standard care. Each site provided either the comprehensive postacute stroke intervention or standard care according to the randomisation assignment. Working together, the study team, institutional review board and members of the community designed an ethically appropriate and operationally reasonable consent process which was carried out successfully at all randomised sites. This achievement is noteworthy because it demonstrates how to effectively conduct appropriate informed consent in cluster randomised trials, and because it provides a model that can easily be adapted for other pragmatic studies. With this innovative approach to informed consent, patients have access to the information they need about research occurring where they are seeking care, and medical researchers can conduct their studies without ethical concerns or unreasonable logistical impediments.

TRIAL REGISTRATION NUMBER

NCT02588664, recruiting. This article covers the development of consent process that is currentlty being employed in the study.

Physical activity and family-based obesity treatment: a review of expert recommendations on physical activity in youth

Targeting physical inactivity in children is pertinent to aiding in the decrease of childhood obesity rates. Only 33% of adolescents are obtaining the recommended goal of at least 60 min of physical activity per day. The objectives of this review are to summarize professional recommendations for physical activity and exercise in children and adolescents, and identify family-centred strategies that can be implemented by weight management clinicians. Clinically oriented recommendations and policy statements from professional organizations were identified through literature and internet searches, summarized using rubrics of aerobic, muscle strengthening and bone strengthening exercise, then examined for details on family-based focus, inclusion of child developmental stage and age, and application to the prevention and treatment of obesity. Current recommendations give guidelines for the amount of physical activity that children should acquire and how many days a week activities should occur. However, available guidelines need an improved approach to addressing the role of the parents and caregivers in targeting physical activity and weight management in youth. Efforts must be taken in order to make sure that the types of physical activity offered are both suitable and enjoyable. Sports, games, free play and other age appropriate activities are adequate ways to increase moderate to vigorous physical activity in children. Differentiating physical activities types in accordance with developmental stage, level of enjoyment, and family characteristics is needed to establish sustainable habits. One paediatric obesity program has developed approaches to teaching families fun and engaging ways to be active together.

The effect of supplementation with alkaline potassium salts on bone metabolism: a meta-analysis

The role of acid-base metabolism in bone health is controversial. In this meta-analysis, potassium bicarbonate and potassium citrate lowered urinary calcium and acid excretion and reduced the excretion of the bone resorption marker NTX. These salts may thus be beneficial to bone health by conserving bone mineral.

INTRODUCTION

The role of acid-base homeostasis as a determinant of bone health and the contribution of supplemental alkali in promoting skeletal integrity remain a subject of debate. The objective of this study was, therefore, to conduct a meta-analysis to assess the effects of supplemental potassium bicarbonate (KHCO3) and potassium citrate (KCitr) on urinary calcium and acid excretion, markers of bone turnover and bone mineral density (BMD) and to compare their effects with that of potassium chloride (KCl).

METHODS

A total of 14 studies of the effect of alkaline potassium salts on calcium metabolism and bone health, identified by a systematic literature search, were analysed with Review Manager (Version 5; The Cochrane Collaboration) using a random-effects model. Authors were contacted to provide missing data as required. Results are presented as the standardised (SMD) or unstandardized mean difference (MD) (95 % confidence intervals).

RESULTS

Urinary calcium excretion was lowered by intervention with both KHCO3 (P = 0.04) and KCitr (P = 0.01), as was net acid excretion (NAE) (P = 0.002 for KHCO3 and P = 0.0008 for KCitr). Both salts significantly lowered the bone resorption marker NTX (P < 0.00001). There was no effect on bone formation markers or BMD. KHCO3 and KCitr lowered calcium excretion to a greater extent than did KCl.

CONCLUSIONS

This meta-analysis confirms that supplementation with alkaline potassium salts leads to significant reduction in renal calcium excretion and acid excretion, compatible with the concept of increased buffering of hydrogen ions by raised circulating bicarbonate. The observed reduction in bone resorption indicates a potential benefit to bone health.

Carotid arterial stiffness and its relationship to exercise intolerance in older patients with heart failure and preserved ejection fraction

Heart failure with a preserved ejection fraction (HFpEF) is the dominant form of heart failure in the older population. The primary chronic symptom in HFpEF is severe exercise intolerance; however, its pathophysiology and therapy are not well understood. We tested the hypothesis that older patients with HFpEF have increased arterial stiffness beyond what occurs with normal aging and that this contributes to their severe exercise intolerance. Sixty-nine patients ≥60 years of age with HFpEF and 62 healthy volunteers (24 young healthy subjects ≤30 years and 38 older healthy subjects ≥60 years old) were examined. Carotid arterial stiffness was assessed using high-resolution ultrasound, and peak exercise oxygen consumption was measured using expired gas analysis. Peak exercise oxygen consumption was severely reduced in the HFpEF patients compared with older healthy subjects (14.1±2.9 versus 19.7±3.7 mL/kg per minute; P<0.001) and in both was reduced compared with young healthy subjects (32.0±7.2 mL/kg per minute; both P<0.001). In HFpEF compared with older healthy subjects, carotid arterial distensibility was reduced (0.97±0.45 versus 1.33±0.55×10(-3) mm Hg(-1); P=0.008) and Young's elastic modulus was increased (1320±884 versus 925±530 kPa; P<0.02). Carotid arterial distensibility was directly (0.28; P=0.02) and Young's elastic modulus was inversely (-0.32; P=0.01) related to peak exercise oxygen consumption. Carotid arterial distensibility is decreased in HFpEF beyond the changes attributed to normal aging and is related to peak exercise oxygen consumption. This supports the hypothesis that increased arterial stiffness contributes to exercise intolerance in HFpEF and is a potential therapeutic target.

Global analysis of Oja's flow for neural networks

A detailed study of Oja's learning equation in neural networks is undertaken in this paper. Not only are such fundamental issues as existence, uniqueness, and representation of solutions completely resolved, but also the convergence issue is resolved. It is shown that the solution of Oja's equation is exponentially convergent to an equilibrium from any initial value. Moreover, the necessary and sufficient conditions are given on the initial value for the solution to converge to a dominant eigenspace of the associated autocorrelation matrix. As a by-product, this result confirms one of Oja's conjectures that the solution converges to the principal eigenspace from almost all initial values. Some other characteristics of the limiting solution are also revealed. These facilitate the determination of the limiting solution in advance using only the initial information. Two examples are analyzed demonstrating the explicit dependence of the limiting solution on the initial value. In another respect, it is found that Oja's equation is the gradient flow of generalized Rayleigh quotients on a Stiefel manifold.

A randomized double-blind trial of enalapril in older patients with heart failure and preserved ejection fraction: effects on exercise tolerance and arterial distensibility

BACKGROUND

Exercise intolerance is the primary symptom in older patients with heart failure and preserved ejection fraction (HFPEF); however, little is known regarding its mechanisms and therapy.

METHODS AND RESULTS

Seventy-one stable elderly (70+/-1 years) patients (80% women) with compensated HFPEF and controlled blood pressure were randomized into a 12-month follow-up double-blind trial of enalapril 20 mg/d versus placebo. Assessments were peak exercise oxygen consumption; 6-minute walk test; Minnesota Living with HF Questionnaire; MRI; Doppler echocardiography; and vascular ultrasound. Compliance by pill count was excellent (94%). Twenty-five patients in the enalapril group versus 34 in the placebo group completed the 12-month follow-up. During follow-up, there was no difference in the primary outcome of peak exercise oxygen consumption (enalapril, 14.5+/-3.2 mL/kg/min; placebo, 14.3+/-3.4 mL/kg/min; P=0.99), or in 6-minute walk distance, aortic distensibility (the primary mechanistic outcome), left ventricle mass, or neurohormonal profile. The effect size of enalapril on peak exercise oxygen consumption was small (0.7%; 95% CI, 4.2% to 5.6%). There was a trend toward improved Minnesota Living with HF Questionnaire total score (P=0.07), a modest reduction in systolic blood pressure at peak exercise (P=0.02), and a marginal improvement in carotid arterial distensibility (P=0.04).

CONCLUSIONS

In stable, older patients with compensated HFPEF and controlled blood pressure, 12 months of enalapril did not improve exercise capacity or aortic distensibility. These data, combined with those from large clinical event trials, suggest that angiotensin inhibition does not substantially improve key long-term clinical outcomes in this group of patients. This finding contrasts sharply with observations in HF with reduced EF and highlights our incomplete understanding of this important and common disorder.

Endurance exercise training in older patients with heart failure: results from a randomized, controlled, single-blind trial

OBJECTIVES

To test the hypothesis that exercise training (ET) improves exercise capacity and other clinical outcomes in older persons with heart failure with reduced ejection fraction (HfrEF).

DESIGN

Randomized, controlled, single-blind trial.

SETTING

Outpatient cardiac rehabilitation program.

PARTICIPANTS

Fifty-nine patients aged 60 and older with HFrEF recruited from hospital records and referring physicians were randomly assigned to a 16-week supervised ET program (n=30) or an attention-control, nonexercise, usual care control group (n=29).

INTERVENTION

Sixteen-week supervised ET program of endurance exercise (walking and stationary cycling) three times per week for 30 to 40 minutes at moderate intensity regulated according to heart rate and perceived exertion.

MEASUREMENTS

Individuals blinded to group assignment assessed four domains pivotal to HFrEF pathophysiology: exercise performance, left ventricular (LV) function, neuroendocrine activation, and health-related quality of life (QOL).

RESULTS

At follow-up, the ET group had significantly greater exercise time and workload than the control group, but there were no significant differences between the groups for the primary outcomes: peak exercise oxygen consumption (VO(2) peak), ventilatory anaerobic threshold (VAT), 6-minute walk distance, QOL, LV volumes, EF, or diastolic filling. Other than serum aldosterone, there were no significant differences after ET in other neuroendocrine measurements. Despite a lack of a group "training" effect, a subset (26%) of individuals increased VO(2) peak by 10% or more and improved other clinical variables as well.

CONCLUSION

In older patients with HFrEF, ET failed to produce consistent benefits in any of the four pivotal domains of HF that were examined, although the heterogeneous response of older patients with HFrEF to ET requires further investigation to better determine which patients with HFrEF will respond favorably to ET.

Assessment of cardiovascular risk in collegiate football players and nonathletes

Collegiate American football players may be at risk for cardiovascular disease.

OBJECTIVE

to compare cardiovascular disease risk factors and cardiovascular structure and function parameters of football players, stratified by position, to a group of sedentary, nonathletes.

PARTICIPANTS

twenty-six collegiate football players and 13 nonathletes participated in this study.

METHODS

blood pressures, anthropometrics, and blood chemistries were obtained and analyzed using standardized procedures. Resting echocardiography was used to evaluate cardiac morphology and function. Brachial artery flow-mediated dilation was assessed using high-resolution ultrasonography.

RESULTS

the prevalence of the metabolic syndrome was significantly higher amongst the linemen compared to the skill-position players (46% versus 0%, p < .05). Mildly abnormal wall thickness was noted in 20% of the football players. No significant differences in vascular function were observed between the groups.

CONCLUSIONS

the increased prevalence of the metabolic syndrome and its components in the collegiate linemen may increase cardiovascular disease risk.

A cross-sectional examination of growth indicators from Nicaraguan adolescent girls: a comparison of anthropometric data from their Guatemalan counterparts

BACKGROUND

Few studies have examined growth data from adolescent girls in Latin America and almost none have been conducted in Nicaragua. Thus this study examines growth data from Nicaraguan adolescent girls.

AIM

This study describes cross-sectional growth data from a sample of Nicaraguan girls. These data are compared with data from Mexican-US and Guatemalan girls. It is hypothesized that (a) Mexican-US and Guatemalan wealthy ladina girls will show better indicators of nutritional status when compared with the Nicaraguan girls, and (b) the Nicaraguan girls will show similar anthropometric indicators when compared with poor Guatemalan girls.

SUBJECTS AND METHODS

Anthropometric and age at menarche data were collected from a sample of 154 adolescent girls ages 10-17 years living in Managua, Nicaragua.

RESULTS

The findings revealed that these girls are significantly shorter and lighter than US, Mexican-US and wealthy Guatemalan adolescent girls. These girls are also significantly taller and heavier than their poor Guatemalan counterparts.

CONCLUSION

This study reveals that the Nicaraguan girls are undernourished when compared with other Latin American girls living in an improved overall environment. The data also reveal that the Nicaraguan girls have better indicators of nutritional status when compared with a cohort of poor Guatemalan girls.

The relationship of a 6-min walk to VO(2 peak) and VT in older heart failure patients

PURPOSE

To evaluate the relationship between a 6-min walk test (6-MWT) to peak oxygen consumption (VO(2 peak)) and ventilatory threshold (VT) in older heart failure (HF) patients, to validate the equation by Cahalin et al., and to develop a new equation to improve the prediction of VO(2 peak) from 6-MWT.

METHODS

Older patients (>65 yr) with systolic or diastolic HF (N=97) performed an exercise test to peak exertion on an upright bicycle ergometer using an incremental protocol. Gas exchange measures were collected along with continuous electrocardiograph monitoring. 6-MWT was performed on an indoor track at a self-selected pace under standardized conditions. The formula of Cahalin et al. was used to predict VO(2 peak) from 6-MWT, and a new equation was generated from the measured VO(2 peak)-6-MWT relationship from this investigation.

RESULTS

The correlation between 6-MWT and measured VO(2 peak) was moderate (r=0.54) with a standard error of estimate (SEE) of 2.48 mL.kg.min. The correlation between 6-MWT and VT was weak (r=0.23), whereas the correlation between VO(2 peak) and VT was strong (r=0.74). Correlations between the measured and predicted VO(2 peak) values were moderate (r=0.54) for both prediction equations, and the SEE was 2.83 versus 1.34 mL.kg.min for the Cahalin et al. and the new equation, respectively.

CONCLUSION

These results indicate that 6-MWT does not accurately predict functional capacity in older HF patients, and questions the validity of using this test to determine functional capacity in older HF patients. Predicting VO(2 peak) from equations using 6-MWT also results in substantial variability and, consequently, should not be used in older HF patients where an accurate determination of functional capacity is essential.

The Medical College of Georgia Fitkid project: the relations between program attendance and changes in outcomes in year 1

OBJECTIVE

To investigate the relations of attendance of children in an after-school physical activity (PA) program to changes in body composition and cardiovascular fitness (CVF).

DESIGN

Eight-month after-school PA-based intervention.

SUBJECTS

In all, 278 third-grade boys and girls from nine elementary schools (age, 8.7 y (s.d. = 0.6 y), body mass index (BMI) 19.1 kg/m2 (s.d. = 4.4) and percent body fat (%BF) 26.0 (s.d. = 9.0)).

MEASUREMENTS

Body composition (from dual-energy X-ray absorptiometry), BMI (from height and weight), waist circumference (WC) and CVF (from the YMCA submaximal bench-stepping test).

RESULTS

There was a significant negative linear trend between level of attendance in the after-school program and change in %BF and fat mass; there was also a significant positive linear trend between program attendance and change in CVF. There was a marginally significant linear trend between program attendance and fat-free mass. Greater increases in bone mineral density were observed with higher program attendance. Changes in BMI and WC were not influenced by program attendance.

CONCLUSION

Understanding the dose-response effect of PA on health outcomes, particularly body composition, in children is crucial in our effort to prevent overweight and its health consequences. Since there is limited data available to base PA dose recommendations for youths, findings from this study are relevant, and suggest that greater health benefits can be obtained in young children with more frequent participation in PA.

Validity and Reliability of the North Carolina 6-Minute Cycle Test

PURPOSE

The purposes of this investigation were to determine (1) if the 6-minute cycle (6MC) test is a valid and reliable measure of physical performance in cardiac patients and (2) if physiologic responses to the 6-minute walk (6MW) and 6MC tests differ in men and women.

METHODS

Subjects were 101 phase II cardiac rehabilitation patients aged 40 to 79 years. Each subject performed a maximal graded exercise test (MGXT), a 6MW test, and three 6MC tests on separate days.

RESULTS

Pearson product moment correlation r values ranged from 0.78 to 0.89 (P = .001) when the three 6MC tests were compared with one another, indicating good test/retest reliability. The 6MC tests were all significantly and positively correlated to 6MW distance (P < .01), with r values ranging from 0.55 to 0.59. Each 6MC test was also correlated with maximal graded exercise test total time (P < .01), with r values ranging from 0.51 to 0.63, and with estimated maximal metabolic equivalents (P < .01), with r values ranging from 0.44 to 0.60. Although heart rate, systolic blood pressure, rate-pressure product, and rating of perceived exertion values for men were greater during the 6MC test than during the 6MW test (P < .001), no differences were seen in these parameters between tests in women (P = .166 to.260), with the exception of a greater exercise rating of perceived exertion seen during the 6MC test(P = .009).

CONCLUSION

The North Carolina 6MC test seems to provide a valid and reliable measure of functional abilities in phase II cardiac rehabilitation participants. Men generally present with greater heart rate, systolic blood pressure, and rate-pressure product values during this test than do the women when compared with a standard 6MW test.

Menin molecular interactions: insights into normal functions and tumorigenesis

Multiple endocrine neoplasia type 1 (MEN1) is an autosomal dominant disease predisposed by heterozygous germline mutations in the MEN1 tumor suppressor gene. Biallelic loss of MEN1 resulting from small mutation and/or loss of heterozygosity occurs in a large tissue spectrum of MEN1 tumors or non-hereditary tumors. Mouse models of MEN1 underexpression or overexpression have also supported the tumor-suppressor effect of the MEN1 gene. Menin, the 610-amino-acid protein encoded by MEN1, is expressed ubiquitously and found predominantly in the nucleus. Sequence analyses do not reveal motifs of known function other than two nuclear localization sequences. Menin has been found to partner in vitro with a variety of proteins that comprise transcription factors, DNA processing factors, DNA repair proteins, and cytoskeletal proteins. The diverse functions of menin interactors suggest roles for menin in multiple biological pathways. Inactivation of menin switches its JunD partner from a downstream action of growth suppression to growth promotion. This is a plausible mechanism for menin tumorigenesis.

Effects of body mass index on the accuracy of an electronic pedometer

Electronic pedometers are accurate for assessing steps taken while walking in normal weight adults but the accuracy of these devices has not been tested in overweight and obese men and women. The primary purpose of this study was to assess the accuracy of an electronic pedometer for measuring steps taken at various walking speeds in groups of adults with variations in body mass index (BMI). The secondary purpose was to determine if the manufacturer recommended position is the best placement position for overweight and obese adults. Participants were categorized into one of three BMI categories identified by the World Health Organization: normal (N = 25; < 25 kg x m(-2)), overweight (N = 24; 25 - 29.9 kg x m(-2)), or obese (N = 17; > or = 30 kg x m(-2)). Participants walked on a treadmill for 3 min at 54, 67, 80, 94, and 107 m x min(-1) for a total of 15 min. During the treadmill walking, three electronic pedometers tallied steps taken. The pedometers were placed at the waist level, one on the anterior mid-line of the thigh (front; manufacturer recommended placement), one on the mid-axillary line (side), and one on the posterior mid-line of the thigh (back). Concurrently, a researcher counted steps using a hand-tally counter. Category of BMI did not affect the accuracy of the pedometer at any walking speed (54 m x min(-1), p = 0.991; 67 m x min(-1), p = 0.556; 80 m x min(-1), p = 0.591; 94 m x min(-1), p = 0.426; 107 m x min(-1), p = 0.869). At 54 m x min(-1), the front, side, and back pedometers significantly underestimated hand-tally counted steps by 20 % (p < 0.001), 33 % (p < 0.001), and 26 % (p < 0.001), respectively. At 67 m x min(-1) the front, side, and back pedometers significantly underestimated hand-tally counted steps by 7 % (p = 0.027), 13 % (p < 0.001), 11 % (p = 0.002), respectively. The steps recorded by the electronic pedometers placed at the front, side and back of the waist were not significantly different than steps counted by the hand-tally counter at speeds of 80 m x min(-1) and higher for all subjects combined. An electronic pedometer accurately quantified steps walked at speeds of 80 m x min(-1) or faster in persons with a normal BMI and those classified as overweight or obese. The placement of the pedometer on the front, side or back of the waistband did not affect accuracy of the pedometer for counting steps.

Increasing daily walking improves glucose tolerance in overweight women

BACKGROUND

Physical activity (PA) has been shown to benefit glucose tolerance. Walking is a convenient low-impact mode of PA and is reported to be the most commonly performed activity for those with diabetes. The purpose of this study was to determine whether a recommendation to accumulate 10,000 steps/day for 8 weeks was effective at improving glucose tolerance in overweight, inactive women.

METHODS

Eighteen women (53.3 +/- 7.0 years old, 35.0 +/- 5.1 kg/m(2)) with a family history of type 2 diabetes completed a 4-week control period followed by an 8-week walking program with no changes in diet. The walking program provided a goal of accumulating at least 10,000 steps/day, monitored by a pedometer.

RESULTS

During the control period, participants walked 4972 steps/day. During the intervention period, the participants increased their accumulated steps/day by 85% to 9213, which resulted in beneficial changes in 2-h postload glucose levels (P < 0.001), AUC(glucose) (P = 0.025), systolic blood pressure (P < 0.001), and diastolic blood pressure (P = 0.002). There were no changes in body mass, body fat percentage, and waist circumference during the walking intervention.

CONCLUSIONS

The 10,000 steps/day recommendation resulted in improved glucose tolerance and a reduction in systolic and diastolic blood pressure in overweight women at risk for type 2 diabetes. This demonstrates that activity can be accumulated throughout the day and does not have to result in weight loss to benefit this population.

Discovery of the first non-peptide antagonist of the motilin receptor

A first-in-class non-peptide antagonist of the motilin receptor was identified through electronic screening of our corporate database against a 3D pharmacophore. The pharmacophore was developed from the motilin 22 residue endogenous peptide using NMR structural data, principles of peptide folding, and peptide structure activity relationships. The NMR data supported helical content within the peptide, and both the hydrophobic staple and N-capping box motifs were identified in the motilin sequence. The conformational features of these motifs were imposed on the peptide structure, providing a constrained conformer as a starting point for database searching. A trisubstituted cyclopentene lead was identified directly from the electronic search. Compounds in this series inhibit the binding of 125I-motilin to human antral smooth muscle membrane and antagonize motilin-induced intracellular calcium mobilization in cells expressing the human motilin receptor. A potent compound developed through optimization, RWJ 68023, is active in binding and cell-based functional assays and is also effective in inhibiting motilin-induced contractility in segments of rabbit duodenum. This orally active compound is currently undergoing clinical evaluation for the treatment of gastrointestinal disorders associated with altered motility.

cDNA array analysis identifies thymic LCK as upregulated in moderate murine zinc deficiency before T-lymphocyte population changes

The detrimental sequelae of severe zinc deficiency on the thymus and T-lymphocyte compartment of the mammalian immune system have been established, but underlying mechanisms remain unknown. Hypothesizing that the alterations in T-lymphocyte number and function observed during zinc deficiency may result from changes in gene expression, we sought to compare thymic mRNA expression profiles of zinc-deficient and zinc-normal mice utilizing cDNA arrays. For our murine model described herein, 3 wk of dietary zinc deficiency did not perturb food intake or growth rate in young adult, outbred mice, but significantly depressed multiple parameters of zinc status. Furthermore, fluorescence-activated cell sorting (FACS) analysis demonstrated no changes in thymocyte populations expressing the cell surface markers CD3, CD4 or CD8, establishing that observed changes in mRNA abundances were not attributable to different thymocyte populations. Yet notably, at this moderate level of zinc deficiency, cDNA array analysis identified four potentially zinc-regulated mRNAs whose modulation was confirmed independently, twice, using both semiquantitative and real-time quantitative reverse transcription-polymerase chain reaction. Expression of one of these genes (myeloid cell leukemia sequence-1) was depressed, whereas the others [DNA damage repair and recombination protein 23B, the mouse laminin receptor and the lymphocyte-specific protein tyrosine kinase (LCK)] were elevated in the zinc-deficient mice. Further Western analysis demonstrated that the zinc binding protein LCK was elevated in these zinc-deficient mice. Results demonstrate that 3 wk of dietary zinc insufficiency can alter specific thymic mRNA and protein abundances before alterations occur in thymocyte development as detectable by FACS analysis.

Modulation of intestinal gene expression by dietary zinc status: effectiveness of cDNA arrays for expression profiling of a single nutrient deficiency

Mammalian nutritional status affects the homeostatic balance of multiple physiological processes and their associated gene expression. Although DNA array analysis can monitor large numbers of genes, there are no reports of expression profiling of a micronutrient deficiency in an intact animal system. In this report, we have tested the feasibility of using cDNA arrays to compare the global changes in expression of genes of known function that occur in the early stages of rodent zinc deficiency. The gene-modulating effects of this deficiency were demonstrated by real-time quantitative PCR measurements of altered mRNA levels for metallothionein 1, zinc transporter 2, and uroguanylin, all of which have been previously documented as zinc-regulated genes. As a result of the low level of inherent noise within this model system and application of a recently reported statistical tool for statistical analysis of microarrays [Tusher, V.G., Tibshirani, R. & Chu, G. (2001) Proc. Natl. Acad. Sci. USA 98, 5116-5121], we demonstrate the ability to reproducibly identify the modest changes in mRNA abundance produced by this single micronutrient deficiency. Among the genes identified by this array profile are intestinal genes that influence signaling pathways, growth, transcription, redox, and energy utilization. Additionally, the influence of dietary zinc supply on the expression of some of these genes was confirmed by real-time quantitative PCR. Overall, these data support the effectiveness of cDNA array expression profiling to investigate the pleiotropic effects of specific nutrients and may provide an approach to establishing markers for assessment of nutritional status.

Regulation of both gene expression and protein stability provides genetically assisted target evaluation (GATE) for microbial target validation

The attempt to develop novel antibiotics, active against organisms resistant to current therapies, has led researchers to seek and explore new drug targets. The rapid sequencing and analysis of entire microbial genomes has identified large numbers of genes that may be sufficiently different from their human counterparts to be exploited as targets for antimicrobial treatment. As a first step, the importance of the various putative targets for microbial growth and survival must be assessed. Emerging validation technologies are becoming increasingly sophisticated and, in certain cases, allow prioritisation of the best targets. In this paper, genetically assisted target evaluation (GATE) is introduced as a versatile target validation technology. GATE concomitantly manipulates both synthesis and stability of the targeted protein using copper ions as an effector. This technology allows rapid quantitation of the lethal consequences of inactivation of targeted gene products in Saccharomyces cerevisiae. Additional tools can then be applied to extend these results into pathogenic organisms, such as Candida albicans.

Heterologous expression of Trypanosoma cruzi trans-sialidase in Leishmania major enhances virulence

Earlier studies showed that mice primed for a few hours with the trans-sialidase (TS) of Trypanosoma cruzi, the agent of Chagas' disease, become highly susceptible to trypanosomal infection. These studies suggest that TS affects parasite virulence independent of antigenic stimulation. Potentially, TS could enhance or reduce the virulence of heterologous microbes depending on the mechanism of TS action and on the type of immune response elicited by the particular parasite. We tested this hypothesis by expressing heterologous TS in Leishmania major, a protozoan parasite that causes cutaneous leishmaniasis and lacks TS and the TS product alpha2-3-linked sialic acid. Leishmania cells transfected with a T. cruzi TS expression construct made high levels of active enzyme, which was present in the promastigotes and shed into the extracellular milieu. TS expression did not affect L. major binding to and entry into cultured macrophages or its tropism for macrophage infection in vivo. However, TS-expressing L. major exhibited elevated virulence in BALB/c mice, as determined by lesion progression, parasite numbers, and macro- and microscopic examination of cutaneous lesions. Several genetic tests proved that the enhanced virulence was directly attributable to TS expression. The results are consistent with TS functioning to sabotage the mouse immune system to confer a growth advantage on T. cruzi and transgenic L. major. These data suggest that heterologous expression of T. cruzi virulence factors in Leishmania may provide a new approach for dissecting their function in vivo.

Measurement of Orem's basic conditioning factors: a review of published research

The purpose of this review was to examine published research on basic conditioning factors described in Orem's self-care deficit theory of nursing, in order to identify operational definitions, measurement strategies, and the results of the analyses. Thirty-five research articles published between 1987 and 1997 met the criteria for inclusion in the review. Consensus or lack of consensus in operational definitions for specific factors was determined and successful measurement methods were identified. Recommendations are made for revising conceptual and operational definitions. Suggested measurement strategies for the factors are discussed.

The relationship of self-concept and self-care in children with cancer

The purposes of this descriptive study were to examine the relationships between self-concept and (a) self-care, (b) dependent-care, and (c) basic conditioning factors for children with cancer, and to compare the self-concept of children on- and off-therapy. The theoretical framework was Orem's self-care deficit theory of nursing. The sample consisted of 74 children with cancer and their mothers. Results showed small but significant correlations between variables, providing some evidence that if children had higher self-concept scores they performed more self-care activities and received more dependent-care from their mothers. The self-concept scores of the on- and off-therapy groups were not significantly different. This study supports Orem's theory and reinforces the need to promote positive self-concept.

Design and discovery of RWJ 22108--a novel bronchoselective calcium channel blocker

A series of cyclic sulfone dihydropyridines ranging in sulfone ring size from five to nine membered have been evaluated for calcium antagonist activity. Increasing the sulfone ring size from 5 to 8 membered resulted in a two orders of magnitude in vitro potency increase. Aromatic substitution which favored tracheal effects over aortic effects was found to be 2-NO2 and 2-Cl, 6-F. The ester side chain which was found to maximize in vivo activity was the N-benzyl-N-methyl aminoethyl moiety. Combination of all these structural features resulted in RWJ 22108, a bronchoselective calcium channel blocker which preclinically exhibits an antiasthmatic profile.

Response of rat adrenal neuropeptide Y and tyrosine hydroxylase mRNA to acute stress is enhanced by long-term voluntary exercise

Neuropeptide Y (NPY) and catecholamines are synthesized in response to stress. Adrenal NPY mRNA and tyrosine hydroxylase (TH) mRNA were measured by Northern analysis 2 h after a single 20 min bout of shaker stress in exercised and sedentary male Sprague-Dawley rats. Long-term exercise (18 weeks of voluntary wheel running) alone did not significantly alter adrenal NPY mRNA or TH mRNA levels. However, increases in stress-induced NPY and TH mRNA abundances were significantly enhanced by long-term exercise (P < 0.01). These results suggest that long-term physical activity may enhance the ability to synthesize NPY and catecholamines under conditions of stress.

Insertional mutagenesis by a modified in vitro Ty1 transposition system

Transposable elements are useful tools for insertional mutagenesis and have many potential applications in the characterization of complex genomes. Here we describe a system which facilitates the construction of large transposon insertion libraries useful for genome sequencing and functional genomic analysis. We developed two transposons, TyK and TyK'GFP+, which can be introduced into target DNAs by Ty1-mediated transposition in vitro, and several modifications which decrease the frequency of false transposition events and direct the recovery of transpositions into passenger rather than vector DNA. Insertions of TyK'GFP+ additionally may yield fusions to the Aequorea green fluorescent protein (GFP), useful in studies of gene expression and protein targeting. Transposition in vitro was obtained into target DNAs of up to 50 kb in size, restriction mapping showed insertion to be relatively random, and the sequence of 55 insertion sites showed neither strong site nor base compositional preference. Our data suggest that TyK-based artificial transposons will be suitable for a variety of genetic applications in many organisms.

Adjustment responses of children and their mothers to cancer: self-care and anxiety

PURPOSE/OBJECTIVES

To examine children's and their mothers' adjustment responses (self-care and anxiety) to cancer.

DESIGN

A descriptive multivariate study.

SETTING

Two metropolitan pediatric oncology clinics.

SAMPLE

A nonprobability sample of 74.9-18 year olds diagnosed with cancer and their mothers.

METHOD

Children completed two questionnaires--the Children's Self-Care Performance Questionnaire and Children's State-Trait Anxiety Inventory. Mothers completed the Dependent Care Agent Performance Questionnaire, the State-Trait Anxiety Inventory, and a demographic data form.

FINDINGS

Multivariate analysis of variance indicated that children off therapy and their mothers had better adjustment responses than those on therapy. Basic conditioning factors significantly predicted children's self-care practices and state and trait anxiety as well as mothers' dependent-care and state anxiety. A significant canonical correlation surfaced between the set of children's adjustment responses and the set of mothers' adjustment responses.

CONCLUSIONS

Children who have completed treatment for cancer and their mothers have better adjustment responses than those still receiving therapy. Basic conditioning factors predict adjustment responses, and a relationship exists between the adjustment responses of children and those of their mothers.

IMPLICATIONS FOR NURSING PRACTICE

Further research is needed to investigate children's self-care practices, determine mothers' dependent-care practices, and compare children with cancer to a normative sample. In clinical practice nurses must consider the profound effect of cancer on the mother and child the anxiety levels of children with cancer and their mothers, and the influence of these individuals on each other.

Testing Orem's theory of self-care deficit: dependent care agent performance for children

The purpose of this study was to test Orem's theory of self-care deficit, one of three constituent theories included in her general self-care deficit theory of nursing. Specifically, the relationship between dependent care agent performance and basic conditioning factors was examined. Dependent care agent performance for children was defined as health promotion and self-care activities provided by a responsible adult on behalf of the child. The Dependent Care Agent Questionnaire was used with a sample of 380 mothers of children from ages 1 to 16 years. The hypothesis that basic conditioning factors influenced dependent care agent performance was supported (R2 = .13, p = .0001).

Genistein suppresses mammary cancer in rats

Female Sprague-Dawley CD rats were injected s.c. with 5 mg genistein, a soy phytoestrogen, or 20 microliters of the vehicle, dimethylsulfoxide (DMSO), on days 2,4 and 6 postpartum. At day 50, they were exposed to 80 micrograms dimethylbenz[a]anthracene (DMBA)/g body wt. Animals treated neonatally with genistein as compared to DMSO had increased latency and reduced incidence and multiplicity of DMBA-induced mammary adenocarcinomas. Mammary whole mount analysis showed that 50 day old female rats treated neonatally with genistein had fewer terminal end buds. Cell proliferation studies revealed that 50 day old genistein-treated rats had lower percentages and total numbers of cells in the S-phase of the cell cycle in terminal end buds, terminal ducts, lobules I and lobules II. In genistein-treated as compared to vehicle-treated female rats, vaginal openings occurred earlier, the estrus cycle was disrupted and the uterine-ovarian weights were smaller. In 50 day old genistein-treated females there were atretic antral follicles, fewer corpora lutea, and lower circulating progesterone but not estradiol-17 beta concentrations. In 21 day old rats treated neonatally with genistein, mammary glands were larger and there were more terminal end buds and terminal ducts, and more proliferative activity in all terminal ductals structures. It appears that neonatal genistein-treatment exerted its chemoprevention action by acting directly to enhance maturation of terminal ductal structures and by altering the endocrine system to reduce cell proliferation in the mammary gland.

Measuring the self-care practice of children and adolescents: instrument development

PURPOSE

To develop an instrument to measure the self-care practice of children and adolescents.

SUBJECTS

471 students, age 9-18, in 4th-12th grade.

METHODS

This methodological study involved item development and testing the instrument for reliability, readability, and construct validity.

FINDINGS

Study findings for the 35-item Child and Adolescent Self-Care Practice Questionnaire included a coefficient alpha of .83 and moderate correlations with two self-care agency instruments. Factors corresponding to the self-care requisites in Orem's model were identified using a LISREL confirmatory factor analysis approach.

CONCLUSIONS & IMPLICATIONS FOR NURSING

The Child and Adolescent Self-Care Practice Questionnaire can be used in further research to determine how children and adolescents perform as self-care agents. Activities are identified and measured, intervention strategies to improve behaviors can be planned.

Identification and sequencing of the Thermotoga maritima lacZ gene, part of a divergently transcribed operon

The lacZ gene encoding a beta-galactosidase (beta Gal) from the hyperthermophile Thermotoga maritima was cloned on an 11-kb fragment by complementation of an Escherichia coli lacZ deletion stain. The nucleotide sequence of the structural gene and two other ORFs found within a 6317-bp region were determined. The deduced amino acid (aa) sequence of the Tt. maritima beta Gal predicts a 1037-aa polypeptide with a calculated M(r) of 122,312. The translated sequence is 30% similar to nine other beta Gal sequences from bacteria and one yeast. Alignment of the Tt. maritima beta Gal with these other sequences reveals that the residues responsible for Mg2+ binding, catalysis and substrate recognition are conserved in the thermophilic enzyme. Sequence analysis also revealed the presence of a divergently transcribed operon containing at least two other genes 5' to lacZ. These ORFs encode proteins homologous to a second family of beta Gal found in Bacillus species and to an ATP-dependent family of bacterial oligopeptide transport proteins.

Deletion of fowlpox virus homologues of vaccinia virus genes between the 3 beta-hydroxysteroid dehydrogenase (A44L) and DNA ligase (A50R) genes

A fragment of 4156 bp of fowlpox virus (FPV) genomic DNA contains homologues of vaccinia virus 3 beta-hydroxysteroid dehydrogenase/delta 5-delta 4 isomerase (3 beta-HSD; A44L) and DNA ligase (A50R) genes. The FPV locus has clearly been rearranged relative to that of vaccinia virus as homologues of genes A45R to A49R, including the thymidylate kinase and a gene with homology to superoxide dismutase, are deleted. The deleted genes are replaced by two open reading frames: for a serine proteinase inhibitor with homology to vaccinia virus gene K2L and for a protein with no significant homology to proteins in the databases. In addition, the FPV homologues of A44L and A50R are in the same polarity in FPV whereas they are in opposite polarities in vaccinia virus. Increased 3 beta-HSD activity has been demonstrated in cells infected with either of two different strains of FPV or with canarypox virus.

Children's knowledge and affective response to AIDS

Given the urgency of the AIDS crisis, the current emphasis is on prevention of the disease. School-age children may be considered a vulnerable population at risk for future development of HIV infection. Prevention needs to involve educational programs founded on children's knowledge and beliefs about AIDS. Scant literature exists on children's cognition and affective response to AIDS. In this study, 58 school-age children were interviewed to determine their attitudes, beliefs, and emotional response to AIDS. Findings indicate that, in this sample, children had little specific knowledge of AIDS etiology, transmission, or treatment. They expressed negative emotional response to the discussion of AIDS. Health educational programs need to be designed to target children's need for accurate AIDS information that reflects their developmental stage.

Measurement of regional blood oxygenation and cerebral hemodynamics

An echo planar linewidth mapping technique, Shufflebutt, has allowed temporal measurements of changes in linewidth caused by static inhomogeneities (delta LWSI) and transverse relaxation rate (delta R2) in models of hypoxia and hypercapnia. We demonstrate these changes are due to intravascular susceptibility differences/(delta chi) between the blood and tissue. Contrast agent injections at a delta chi equivalent to that of deoxygenated blood showed a twofold difference between the contrast agent and physiological anoxia values. Hypercapnia decreased both delta LWSI and delta R2 consistent with an increase in blood oxygenation. We attribute these findings to constant oxygen extraction during an increase in blood flow, resulting in less deoxygenated venous blood and thus reduced delta chi. For in vivo perturbations we found that delta R2/delta R2' approximately 0.33, a ratio much different from that measured in whole blood phantoms (delta R2/delta R2' approximately 2). This demonstrates that signal changes in these studies are produced predominantly by dephasing of extravascular protons due to field inhomogeneities produced by intravascular deoxygenated hemoglobin (deoxyHb).

RWJ 26629, a new potassium channel opener and vascular smooth muscle relaxant: a potential antihypertensive and antianginal agent

The effects of trans-5,6-dihydro-6-hydroxy-5,5-dimethyl-2-nitro-7-(2-oxopiperidin -1-yl)-7H- thieno[3,2-b]pyran (RWJ 26629) were compared with those of the standard potassium channel opener cromakalim and several standard calcium channel blockers. RWJ 26629 lowered the mean arterial blood pressure in conscious spontaneously hypertensive (ED30 = 10 micrograms/kg p.o. or 8 micrograms/kg i.v.) and renal hypertensive (15 micrograms/kg p.o.) rats, conscious renal hypertensive (ED20 = 4 micrograms/kg p.o.) and normotensive (ED20 = 5 micrograms/kg p.o. or 2 micrograms/kg i.v.) dogs and anesthetized rhesus monkeys (ED20 = 6 micrograms/kg i.v.). RWJ 26629 was more potent than cromakalim and had a maximal activity greater than the calcium channel blockers. At antihypertensive doses, RWJ 26629 had no significant effect on cardiac force, cardiac output, stroke volume or stroke work in dogs and had little or no effect on renal, carotid or femoral blood flow or vascular resistance. RWJ 26629 was also selective for antihypertensive activity in rats compared with its ability to inhibit intestinal motility. However, RWJ 26629 did relax contracted pulmonary smooth muscle in vivo at antihypertensive doses. All compounds tested caused reflex tachycardia in conscious dogs, although this effect was lowest for RWJ 26629. Most importantly, RWJ 26629 potently and selectively increased coronary blood flow with a potency and duration of action greater than that of cromakalim or nifedipine without affecting contractile force. In vitro, RWJ 26629 selectively relaxed precontracted coronary arteries compared with its effect on femoral arteries.(ABSTRACT TRUNCATED AT 250 WORDS)

RWJ-22108--a novel airway tissue--selective calcium channel blocker

RWJ-22108 is a novel calcium entry blocker that has potential therapeutic use as an antiasthmatic agent. Although displaying typical potent inhibition of 45Ca uptake into aortic rings (IC50 = 7.1 nM) and displacement of [3H]nitrendipine from cardiac membranes (IC50 = 137 nM), RWJ-22108 demonstrates tissue selectivity in the inhibition of KCl-induced contractions. RWJ-22108 inhibits the calcium-dependent contraction of canine bronchiolar smooth muscle with an IC50 of 5.7 nM. The IC50 femoral artery/IC50 bronchiolar ratios are 2.85, 8.02, 1.47 and 1.96 for nifedipine, RWJ-22108, verapamil, and gallopamil, respectively. Furthermore, this selectivity ratio (range 2.8-5.5) of RWJ-22108 is also observed when inhibition of other pulmonary and cardiovascular smooth muscles are compared. Using canine tracheal muscle and rabbit aortae, the IC50 aorta/IC50 trachea ratio is 1.75 for RWJ-22108 compared to approximately 0.5 for several calcium blocker standards. These results indicate that in vitro RWJ-22108 is a bronchoselective calcium channel blocker.

Alterations of highly conserved residues in the regulatory domain of nitrogen regulator I (NtrC) of Escherichia coli

Transcription of many nitrogen-regulated (Ntr) genes requires the phosphorylated form of nitrogen regulator I (NRI, or NtrC), which binds to sites that are analogous to eukaryotic enhancers. A highly conserved regulatory domain contains the site of phosphorylation and controls the function of NRI. We analyzed the effects of substitutions in highly conserved residues that are part of the active site of phosphorylation of NRI in Escherichia coli. Fourteen substitutions of aspartate 54, the site of phosphorylation, impaired the response to nitrogen deprivation. Only one of these variants, NRI D-54-->E (NRI-D54E), could significantly stimulate transcription from glnAp2, the major promoter of the glnALG operon. Cells with this variant grew with arginine as a nitrogen source. Experiments with purified components showed that unphosphorylated NRI-D54E stimulated transcription. In contrast, substitutions at aspartate 11 were not as deleterious as those at aspartate 54. Finally, we showed that NRI-K103R, in which arginine replaces the absolutely conserved lysine, is functionally active and efficiently phosphorylated. This substitution appears to stabilize the phosphoaspartate of NRI. The differences between our results and those from study of homologous proteins suggest that there may be significant differences in the way highly conserved residues participate in the transition to the activated state.