Associations between provider-assigned Apgar score and neonatal race.

BACKGROUND: For decades, the Apgar scoring system has been used to evaluate neonatal status and determine need for resuscitation or escalation in care, such as admission to a neonatal intensive care unit. However, the variation and accuracy of provider-assigned Apgar scores across neonatal racial groups have yet to be evaluated. OBJECTIVE: This study aimed to investigate how provider-assigned Apgar scores vary by neonatal race independently of clinical factors and umbilical cord gas values. STUDY DESIGN: We conducted a retrospective cohort study at an urban academic medical center. All live births at ≥23 weeks and 0 days of gestation from January 1, 2019 through December 31, 2019 with complete data available were included. Data were queried from the electronic medical record and included race, ethnicity, gestational age of neonate, umbilical cord gas values (umbilical artery pH and base deficit), admission to the neonatal intensive care unit, and presence of maternal-fetal complications. Primary outcome measures were neonates' Apgar scores at 1 and 5 minutes. Color Apgar score and admission to the neonatal intensive care unit served as secondary outcome measures. We performed 3 partially proportional ordinal regression models controlling for an increasing number of covariates, with Model 1, the baseline model, adjusted for gestational age, Model 2 additionally adjusted for umbilical cord gases, and Model 3 additionally adjusted for maternal medical conditions and pregnancy complications. RESULTS: A total of 977 neonates met selection criteria; 553 (56.6%) were Black. Providers assigned Black neonates significantly lower Apgar scores at 1 minute (odds ratio, 0.63; 95% confidence interval, 0.49-0.80) and 5 minutes (odds ratio, 0.64; 95% confidence interval, 0.47-0.87), when controlling for umbilical artery gases, gestational age, and maternal-fetal complications. This difference seemed related to significantly lower assigned color Apgar scores at 1 minute when controlling for all the above factors (odds ratio, 0.52; 95% confidence interval, 0.39-0.68). Providers admitted full-term Black neonates to the neonatal intensive care unit at higher rates than non-Black neonates when controlling for all factors (odds ratio, 1.29; 95% confidence interval, 0.94-1.77). Black neonates did not have more abnormal cord gas values (mean umbilical artery pH of 7.259 for Black vs 7.256 for non-Black neonates), which would have supported their admission to the neonatal intensive care unit. CONCLUSION: Providers applied inaccurate Apgar scores to Black neonates given that the umbilical cord gases were not in agreement with lower Apgar scores. These inaccuracies may be a factor in unnecessary admissions to neonatal intensive care units, and suggest that colorism and racial biases exist among healthcare providers.

Development of a Novel, Low-Cost, Low-Fidelity Simulation Model for Pudendal Nerve Block Application.

Background: Pudendal nerve block is an important alternative to neuraxial anesthesia, yet studies demonstrate that 3% to 50% of pudendal nerve blocks are ineffective. Lack of clinician training is the most common cause, and there are no simulation models currently described. Objective: To develop and test a novel, low-cost, low-fidelity simulation model for training residents in the placement of a pudendal nerve block. Methods: A pudendal nerve block model was developed using commonly found supplies, with a cost of $20.57. First-year to fourth-year obstetrics and gynecology (OB/GYN) and family medicine (FM) residents were invited to 1 of 4 pudendal nerve block 1-hour simulation sessions from December 2019 to March 2021 during their required teaching sessions. Expert faculty led a discussion of pudendal nerve blocks, then participants practiced with the described model. A survey about the model was created by the authors and administrated prior to and immediately after the session. Pre- and post-surveys were analyzed by Wilcoxon signed rank tests, and Bonferroni correction was performed. Results: Thirty-four out of a total of 36 eligible residents participated (94%). Residents showed improvement in knowledge (median pre-simulation score 43.99 compared with 70.06 post-simulation, P<.00625) and self-assessed confidence (median pre-simulation score 1.7 compared with 3.2 post-simulation, P<.00625) of a pudendal block placement after simulation training. Conclusions: This new, low-cost, reusable, low-fidelity simulation model for pudendal nerve block placement improved knowledge and confidence in OB/GYN and FM residents after 1 hour of simulation training.

The importance of prototype similarity for physical activity: Cross-sectional and longitudinal associations in a large sample of young adolescents.

OBJECTIVES: Physical activity declines during adolescence. The Theory of Planned Behaviour (TPB) is a useful framework for investigating activity but leaves variance unexplained. We explored the utility of a dual-process approach using the TPB and the Prototype Willingness Model (PWM) to investigate correlates of physical activity, and 1-year change in physical activity, among a large sample of adolescents. DESIGN: A cross-sectional and longitudinal analysis of baseline and follow-up data from the Fit to Study cluster-randomized trial. METHODS: A total of 9,699 secondary school pupils at baseline and 4,632 at follow-up (mean age = 12.5 years) completed measures of past week physical activity and constructs from both behaviour-change models, at time-points 1 year apart. Cross-sectional analyses used multilevel, stepwise regression models to measure the strength of associations between model constructs and physical activity, and variance in behaviour explained by PWM over and above TPB. In longitudinal analyses, change scores were calculated by subtracting follow-up from baseline scores. Models controlling for trial treatment status measured the strength of associations between change scores, and variance explained. RESULTS: At baseline, after controlling for past behaviour, physically active prototype similarity had the strongest relationship with activity after the intention to be active. Change in prototype similarity had the strongest relationship with change in activity after the change in intention and attitudes. Prototype perceptions and willingness explained additional variance in behaviour. CONCLUSION: A dual-process model incorporating prototype perceptions could more usefully predict physical activity than models based on rational expectations alone. Behaviour-change interventions promoting an active self-image could be tested for effects on physical activity.

A qualitative examination of the usability of a digital cognitive behavioral therapy for insomnia program after stroke.

OBJECTIVE: Sleep is commonly impaired after stroke. Cognitive Behavioral Therapy for Insomnia (CBT-I) is the first-line recommended treatment for sleep difficulty. "Sleepio" is a digital CBT-I program, allowing delivery of this treatment at scale. However, Sleepio has not yet been tested specifically in people with stroke. Before doing so, we wanted to explore the experience of people with stroke using the program, and potential barriers to completion. METHOD: Community dwelling survivors of stroke (n = 11, 41-78 years of age, 6 male) were given access to Sleepio. Participants discussed their experiences with the program during a semi-structured interview, which was analyzed using thematic analysis. RESULTS: We found four common themes: (1) positive and negative experiences impacted engagement with the program, (2) motivation to follow the program was proportional to perceived severity of sleep problem, (3) impractical advice for people with stroke, (4) difficulty operating the program. CONCLUSION: Sleepio can be used by some people at the chronic stage of stroke. However, some barriers to completion were highlighted, and not all suggestions were deemed practical for everyone. We therefore suggest possible adaptations which may make the program more easily usable and engaging for survivors of stroke with varying impairments.

Exploring activity levels in physical education lessons in the UK: a cross-sectional examination of activity types and fitness levels.

OBJECTIVES: To establish pupil fitness levels, and the relationship to global norms and physical education (PE) enjoyment. To measure and describe physical activity (PA) levels during secondary school PE lessons, in the context of recommended levels, and how levels vary with activity and lesson type. METHODS: A cross-sectional design; 10 697 pupils aged 12.5 (SD 0.30) years; pupils who completed a multistage fitness test and wore accelerometers to measure PA during PE lessons. Multilevel models estimated fitness and PE activity levels, accounting for school and class-level clustering. RESULTS: Cardiorespiratory fitness was higher in boys than girls (ß=-0.48; 95% CI -0.56 to -0.39, p<0.001), within absolute terms 51% of boys and 54% of girls above the 50th percentile of global norms. On average, pupils spent 23.8% of PE lessons in moderate-to-vigorous PA (MVPA), and 7.1% in vigorous PA (VPA). Fitness-focused lessons recorded most VPA in co-educational (ß=1.09; 95% CI 0.43 to 1.74) and boys-only lessons (ß=0.32; 95% CI -0.21 to 0.85). In girls-only lessons, track athletics recorded most VPA (ß=0.13; 95% CI -0.50 to 0.75) and net/wall/racket games (ß=0.97; 95% CI 0.12 to 1.82) the most MVPA. For all lesson types, field athletics was least active (ß=-0.85; 95% CI -1.33 to -0.36). There was a relationship of enjoyment of PE to fitness (ß=1.03; 95% CI 0.83 to 1.23), and this relationship did not vary with sex (ß=-0.14 to 0.23; 95% CI -0.16 to 0.60). CONCLUSIONS: PE lessons were inactive compared with current guidelines. We propose that if we are to continue to develop a range of sporting skills in schools at the same time as increasing levels of fitness and PA, there is a need to introduce additional sessions of PE activity focused on increasing physical activity. TRIAL REGISTRATION NUMBER: NCT03286725.

Multimodal Imaging Brain Markers in Early Adolescence Are Linked with a Physically Active Lifestyle.

The World Health Organization promotes physical exercise and a healthy lifestyle as means to improve youth development. However, relationships between physical lifestyle and human brain development are not fully understood. Here, we asked whether a human brain-physical latent mode of covariation underpins the relationship between physical activity, fitness, and physical health measures with multimodal neuroimaging markers. In 50 12-year old school pupils (26 females), we acquired multimodal whole-brain MRI, characterizing brain structure, microstructure, function, myelin content, and blood perfusion. We also acquired physical variables measuring objective fitness levels, 7 d physical activity, body mass index, heart rate, and blood pressure. Using canonical correlation analysis, we unravel a latent mode of brain-physical covariation, independent of demographics, school, or socioeconomic status. We show that MRI metrics with greater involvement in this mode also showed spatially extended patterns across the brain. Specifically, global patterns of greater gray matter perfusion, volume, cortical surface area, greater white matter extra-neurite density, and resting state networks activity covaried positively with measures reflecting a physically active phenotype (high fit, low sedentary individuals). Showing that a physically active lifestyle is linked with systems-level brain MRI metrics, these results suggest widespread associations relating to several biological processes. These results support the notion of close brain-body relationships and underline the importance of investigating modifiable lifestyle factors not only for physical health but also for brain health early in adolescence.SIGNIFICANCE STATEMENT An active lifestyle is key for healthy development. In this work, we answer the following question: How do brain neuroimaging markers relate with young adolescents' level of physical activity, fitness, and physical health? Combining advanced whole-brain multimodal MRI metrics with computational approaches, we show a robust relationship between physically active lifestyles and spatially extended, multimodal brain imaging-derived phenotypes. Suggesting a wider effect on brain neuroimaging metrics than previously thought, this work underlies the importance of studying physical lifestyle, as well as other brain-body relationships in an effort to foster brain health at this crucial stage in development.

Exploring the public health potential of RED January, a social media campaign supporting physical activity in the community for mental health: a qualitative study.

STATEMENT OF PROBLEM: RED January is an annual social media campaign challenging individuals to be physically active every day during January, and highlighting the potential for improvements in mood and wellbeing. Our aim was to explore elements of the challenge that motivate engagement with, and sustained participation in, physical activity for mental health. METHOD: RED January registrants (n= 55,772, female = 45,802; 82%) were invited to take part. Volunteers supplied information on sex, age band and moderate-to-vigorous physical activity in the past week. Forty registrants (24 female), recruited in December 2019 using a purposive sampling approach to identify a maximum-variation sample, participated in semi-structured interviews (31 face-to-face) after completing the challenge. The resulting transcripts were thematically analysed, using the Framework method. RESULTS: Two main themes relating to motivation were identified. 'Pleasure' referred to how daily activity promoted physical enjoyment and positive affective states via engaging with the environment, finding mental space and peace, and enjoyable social interactions. 'Purpose' referred to the experiences of engaging with the campaign, and observed changes in health outcomes. These included setting flexible and appropriate goals, measuring and reviewing progress, noting wider biological and behavioural changes, and receiving support from the social media community. Points for consideration were feelings of failure when not achieving self-imposed targets, the unintended facilitation of obsessive exercising, and social media posts that triggered negative thoughts among a minority of participants. CONCLUSIONS: Findings suggest RED January may have potential as a public health resource. The challenge might not suit individuals with severe disorders.

Rapid Implementation of Telehealth Services During the COVID-19 Pandemic.

Telehealth is an important tool utilized to provide remote clinical care and has increased in prevalence during the coronavirus disease of 2019 (COVID-19) pandemic. It allows providers to conduct safe, timely, and high-quality ambulatory care for patients without increasing risk of disease exposure for both parties. Major organizations including the Centers for Disease Control and Prevention and American College of Obstetrics and Gynecology have released recommendations encouraging the use of telehealth systems for patient care. In obstetrics and gynecology, practice of telehealth has not been commonplace and no practical procedural guidelines have been published. The authors have created such guidelines for use of telehealth in a moderate-risk academic generalist practice in response to the COVID-19 pandemic. This document highlights the process to determine which obstetrics and gynecology patients are candidates for telehealth, the frequency of follow-up, and the technical aspects of designing and delivering a de novo telehealth system. The guidelines were vital in providing structure amid a sudden transition in an academic setting while ensuring patient and provider safety.

Associations between fitness, physical activity and mental health in a community sample of young British adolescents: baseline data from the Fit to Study trial.

OBJECTIVES: To examine relationships between fitness, physical activity and psychosocial problems among English secondary school pupils and to explore how components of physically active lifestyles are associated with mental health and well-being. METHODS: A total of 7385 participants aged 11-13 took a fitness test and completed self-reported measures of physical activity, attitudes to activity, psychosocial problems and self-esteem during the Fit to Study trial. Multilevel regression, which modelled school-level cluster effects, estimated relationships between activity, fitness and psychosocial problems; canonical correlation analysis (CCA) explored modes of covariation between active lifestyle and mental health variables. Models were adjusted for covariates of sex, free school meal status, age, and time and location of assessments. RESULTS: Higher fitness was linked with fewer internalising problems (ß=-0.23; 95% CI -0.26 to -0.21; p<0.001). More activity was also related to fewer internalising symptoms (ß=-0.24; 95% CI -0.27 to -0.20; p<0.001); the relationship between activity and internalising problems was significantly stronger for boys than for girls. Fitness and activity were also favourably related to externalising symptoms, with smaller effect sizes. One significant CCA mode, with a canonical correlation of 0.52 (p=0.001), was characterised high cross-loadings for positive attitudes to activity (0.46) and habitual activity (0.42) among lifestyle variables; and for physical and global self-esteem (0.47 and 0.42) among mental health variables. CONCLUSION: Model-based and data-driven analysis methods indicate fitness as well as physical activity are linked to adolescent mental health. If effect direction is established, fitness monitoring could complement physical activity measurement when tracking public health.

Effects of gender, activity type, class location and class composition on physical activity levels experienced during physical education classes in British secondary schools: a pilot cross-sectional study.

BACKGROUND: Pupils in secondary schools do not meet the targets for physical activity levels during physical education (PE) sessions, and there is a lack of data on the vigorous physical activity domain (VPA) in PE known to be positively associated with cardio metabolic health While PE session intensity depends on a variety of factors, the large majority of studies investigating these factors have not taken into account the nested structure of this type of data set. Therefore, the aim of this study was to investigate the relationship between various factors (gender, activity type, class location and class composition) and various activity levels during PE classes in secondary schools, using a multi-level statistical approach. METHODS: Year eight (12-13 years old) adolescents (201 boys and 106 girls) from six schools were fitted with accelerometers during one PE session each, to determine the percentage (%) of the PE session time spent in sedentary (SPA), light (LPA), moderate (MPA), vigorous (VPA) and moderate-to-vigorous (MVPA) intensity levels. Two- and three-level (pupils, n = 307; classes, n = 13, schools, n = 6) mixed-effect models were used to assess the relationship between accelerometer-measured physical activity levels (% of class time spent in various activity levels) and gender, activity type, class location and composition. RESULTS: Participants engaged in MVPA and VPA for 30.7 ± 1.2% and 11.5 ± 0.8% of PE classes, respectively. Overall, no significant association between gender or class composition and PA was shown. A significant relationship between activity type and PA was observed, with Artistic classes significantly less active than Fitness classes for VPA (5.4 ± 4.5 vs. 12.5 ± 7.1%, p = 0.043, d:1.19). We also found a significant association between class location and PA, with significantly less time spent in SPA (24.8 ± 4.8% vs. 30.0 ± 3.4%, p = 0.042, d:0.77) and significantly more time spent in VPA (12.4 ± 3.7% vs. 7.6 ± 2.0%, p = 0.022, d:1.93) and MVPA (32.3 ± 6.7% vs.24.8 ± 3.8%, p = 0.024, d:1.33) in outdoors vs. indoors classes. CONCLUSIONS: The results suggest that class location and activity type could be associated with the intensity of PA in PE. It is essential to take into account the clustered nature of this type of data in similar studies if the sample size allows it.

Fit to Study: Reflections on designing and implementing a large-scale randomized controlled trial in secondary schools.

BACKGROUND: The randomised controlled trial (RCT) design is increasingly common among studies seeking good-quality evidence to advance educational neuroscience, but conducting RCTs in schools is challenging. Fit to Study, one of six such trials funded by the Education Endowment Foundation and Wellcome Trust, tested an intervention to increase vigorous physical activity during PE lessons on maths attainment among pupils aged 12-13. This review of designing and conducting an RCT in 104 schools is intended as a resource on which researchers might draw for future studies. METHOD: We consider intervention design and delivery; recruitment, retention, trial management, data collection and analysis including ethical considerations and working with evaluators. RESULTS: Teacher training, intervention delivery and data collection during large-scale RCTs require a flexible approach appropriate to educational settings, which in turn entails planning and resources. CONCLUSION: Simple interventions, with few outcome measures and minimal missing data, are preferable to more complex designs.

Perceptions of active and inactive prototypes are associated with objective measures of physical activity in adolescents.

The benefits of physical activity are known, but the proportion of adolescents meeting daily activity guidelines remains low. The Theory of Planned Behaviour (TPB), which assumes reasoned intentions explain actions, is a useful framework for predicting activity, but it leaves variance unexplained. The Prototype Willingness Model (PWM) which builds on the TPB, proposes a reasoned action pathway and a second social reactive pathway in which perceptions of social images, or prototypes, explain actions via behavioural willingness. We explored whether variables in the PWM's social reactive pathway explained variance in an objective measure of daily activity, over and above the reasoned action path. Participants aged 12-13 (n = 205) were invited to complete measures of constructs in the PWM and to wear an accelerometer for the next seven days. Overall, 126 students (65 males) participated. Reasoned intentions, attitudes and subjective norms explained 12.8% of variance in activity. Prototype perceptions and willingness explained an additional 13.1% of variance. Participants' perceived similarity to active prototypes, and unfavourable perceptions of inactive prototypes, significantly predicted activity. There were no significant differences between sexes on psychological variables. These findings highlight the importance of targeting prototype perceptions to encourage physical activity in this age group.

Unspoken Playground Rules Discourage Adolescent Physical Activity in School: A Focus Group Study of Constructs in the Prototype Willingness Model.

The health benefits of exercise in school are recognized, yet physical activity continues to decline during early adolescence despite numerous interventions. In this study, we investigated whether the prototype willingness model, an account of adolescent decision making that includes both reasoned behavioral choices and unplanned responses to social environments, might improve understanding of physical activity in school. We conducted focus groups with British pupils aged 12 to 13 years and used deductive thematic analysis to search for themes relating to the model. Participants described reasoned decisions about physical activity outside school and unplanned choices to be inactive during break, in response to social contexts described as more "judgmental" than in primary school. Social contexts appeared characterized by anxiety about competence, negative peer evaluation, and inactive playground norms. The prototype willingness model might more fully explain physical activity in school than reasoned behavioral models alone, indicating potential for interventions targeting anxieties about playground social environments.

Mutations in the NDP gene: contribution to Norrie disease, familial exudative vitreoretinopathy and retinopathy of prematurity.

BACKGROUND: To examine the contribution of mutations within the Norrie disease (NDP) gene to the clinically similar retinal diseases Norrie disease, X-linked familial exudative vitreoretinopathy (FEVR), Coat's disease and retinopathy of prematurity (ROP). METHODS: A dataset comprising 13 Norrie-FEVR, one Coat's disease, 31 ROP patients and 90 ex-premature babies of <32 weeks' gestation underwent an ophthalmologic examination and were screened for mutations within the NDP gene by direct DNA sequencing, denaturing high-performance liquid chromatography or gel electrophoresis. Controls were only screened using denaturing high-performance liquid chromatography and gel electrophoresis. Confirmation of mutations identified was obtained by DNA sequencing. RESULTS: Evidence for two novel mutations in the NDP gene was presented: Leu103Val in one FEVR patient and His43Arg in monozygotic twin Norrie disease patients. Furthermore, a previously described 14-bp deletion located in the 5' unstranslated region of the NDP gene was detected in three cases of regressed ROP. A second heterozygotic 14-bp deletion was detected in an unaffected ex-premature girl. Only two of the 13 Norrie-FEVR index cases had the full features of Norrie disease with deafness and mental retardation. CONCLUSION: Two novel mutations within the coding region of the NDP gene were found, one associated with a severe disease phenotypes of Norrie disease and the other with FEVR. A deletion within the non-coding region was associated with only mild-regressed ROP, despite the presence of low birthweight, prematurity and exposure to oxygen. In full-term children with retinal detachment only 15% appear to have the full features of Norrie disease and this is important for counselling parents on the possible long-term outcome.

Exercise and insulin-mediated capillary recruitment in muscle.

Blood flow to contracting muscles is increased rapidly and is redistributed within the muscle. Recent research has highlighted that insulin causes similar changes, but these are absent in insulin resistance, resulting in impaired insulin-mediated muscle glucose uptake. Understanding the mechanisms and interactions between contraction- and insulin-mediated alterations in blood flow within muscle may reveal new approaches to overcome insulin resistance.

Skeletal muscle contraction stimulates capillary recruitment and glucose uptake in insulin-resistant obese Zucker rats.

Exercise and insulin increase muscle glucose uptake by different mechanisms and also increase capillary recruitment, which is proposed to facilitate access for hormones and nutrients. The genetically obese Zucker rat shows impaired insulin- but not contraction-mediated glucose uptake in muscle. Recently, we have shown the genetically obese Zucker rats to have impaired insulin-mediated capillary recruitment and proposed that this contributes to the insulin resistance of muscle in vivo. Because this might imply a general loss of recruitable capillaries, we now assess responses to contraction in muscles of 18 +/- 3-wk-old lean and obese Zucker rats in vivo. Field stimulation (2 Hz, 0.1 ms) was conducted for 1 h on one leg of anesthetized instrumented rats, and measurements were made of femoral blood flow (FBF), heart rate (HR), blood pressure (BP), hindleg metabolism of 1-methylxanthine (a measure of capillary recruitment), hindleg glucose uptake (HGU), and lower leg muscle glucose uptake by 2-deoxyglucose (R'g). Lean animals (311 +/- 9 g) developed tension at 219 +/- 27 g/g muscle with no change in BP but with significant increases in HR, FBF, HGU, 1-MX metabolism, and R'g (P < 0.05), compared with nonstimulated control leans. Obese animals (469 +/- 7 g) developed tension at 265 +/- 31 g/g muscle with no change in HR or BP but with significant increases in FBF, HGU, 1-MX metabolism, and R'g (P < 0.05) compared with nonstimulated control obese rats. Muscle contraction of lean animals led to a greater increase in lower leg R'g, similar responses in HGU and 1-MX, and a smaller increase in FBF than in obese animals. A tight correlation between FBF and capillary recruitment was noted for all data (P < 0.001). It is concluded that contraction-mediated muscle capillary recruitment and glucose uptake are essentially normal in the obese Zucker rat and that control of FBF and capillary recruitment in exercise is closely linked.

TNF-alpha acutely inhibits vascular effects of physiological but not high insulin or contraction.

TNF-alpha is elevated in many states of insulin resistance, and acutely administered TNF-alpha in vivo inhibits insulin-mediated hemodynamic effects and glucose uptake in muscle. In this study, we assess whether the inhibitory effects of TNF-alpha are affected by insulin dose or muscle contraction. Whole body glucose infusion rate (GIR), femoral blood flow (FBF), hindleg vascular resistance, hindleg glucose uptake (HGU), 2-deoxyglucose uptake into muscles of the lower leg (R'g) and hindleg metabolism of infused 1-methylxanthine (1-MX), a measure of capillary recruitment, were determined. Three groups were studied with and without infusion of TNF-alpha: euglycemic insulin-clamped, one-leg field-stimulated (2 Hz, 0.1 ms at 30 V), and saline-infused control anesthetized rats. Insulin infusions were 3, 10, or 30 mU x kg-1 x min-1 for 2 h x 1-MX metabolism was maximally increased by all three doses of insulin. GIR, HGU, and R'g were maximal at 10 mU and FBF was maximal at 30 mU of insulin. Contraction increased FBF, HGU, and 1-MX. TNF-alpha (0.5 microg x kg-1 x h-1) totally blocked the 3 and 10 mU insulin-mediated increases in FBF and 1-MX, and partly blocked GIR, HGU, and R'g. None of the increases due to twitch contraction was affected by TNF-alpha, and only the increase in FBF due to 30 mU of insulin was partly affected. We conclude that muscle capillary recruitment and glucose uptake due to high levels of insulin or muscle contraction under twitch stimuli at 2 Hz are resistant to TNF-alpha. These findings may have implications for ameliorating muscle insulin resistance resulting from increased plasma TNF-alpha and for the differing mechanisms by which contraction and insulin recruit capillary flow in muscle.

Insulin-mediated hemodynamic changes are impaired in muscle of Zucker obese rats.

Insulin-mediated hemodynamic effects in muscle were assessed in relation to insulin resistance in obese and lean Zucker rats. Whole-body glucose infusion rate (GIR), femoral blood flow (FBF), hindleg glucose extraction (HGE), hindleg glucose uptake (HGU), 2-deoxyglucose (DG) uptake into muscles of the lower leg (R(g)), and metabolism of infused 1-methylxanthine (1-MX) to measure capillary recruitment were determined for isogylcemic (4.8 +/- 0.2 mmol/l, lean; 11.7 +/- 0.6 mmol/l, obese) insulin-clamped (20 mU. min(-1). kg(-1) x 2 h) and saline-infused control anesthetized age-matched (20 weeks) lean and obese animals. Obese rats (445 +/- 5 g) were less responsive to insulin than lean animals (322 +/- 4 g) for GIR (7.7 +/- 1.4 vs. 22.2 +/- 1.1 mg. min(-1). kg(-1), respectively), and when compared with saline-infused controls there was no increase due to insulin by obese rats in FBF, HGE, HGU, and R(g) of soleus, plantaris, red gastrocnemius, white gastrocnemius, extensor digitorum longus (EDL), or tibialis muscles. In contrast, lean animals showed marked increases due to insulin in FBF (5.3-fold), HGE (5-fold), HGU (8-fold), and R(g) ( approximately 5.6-fold). Basal (saline) hindleg 1-MX metabolism was 1.5-fold higher in lean than in obese Zucker rats, and insulin increased in only that of the lean. Hindleg 1-MX metabolism in the obese decreased slightly in response to insulin, thus postinsulin lean was 2.6-fold that of the postinsulin obese. We conclude that muscle insulin resistance of obese Zucker rats is accompanied by impaired hemodynamic responses to insulin, including capillary recruitment and FBF.