Effects of the National Cholesterol Education Program's Step I and Step II dietary intervention programs on cardiovascular disease risk factors: a meta-analysis

BACKGROUND: Plasma lipid and lipoprotein responses have been variable in dietary intervention studies. OBJECTIVE: The objective of this study was to evaluate the effects of the National Cholesterol Education Program's Step I and Step II dietary interventions on major cardiovascular disease risk factors using meta-analysis. DESIGN: MEDLINE was used to select 37 dietary intervention studies in free-living subjects published from 1981 to 1997. RESULTS: Step I and Step II dietary interventions significantly decreased plasma lipids and lipoproteins. Plasma total cholesterol (TC), LDL cholesterol, triacylglycerol, and TC:HDL cholesterol decreased by 0.63 mmol/L (10%), 0.49 mmol/L (12%), 0.17 mmol/L (8%), and 0.50 (10%), respectively, in Step I intervention studies, and by 0.81 mmol/L (13%), 0.65 mmol/L (16%), 0.19 mmol/L (8%), and 0.34 (7%), respectively, in Step II intervention studies (P < 0.01 for all). HDL cholesterol decreased by 7% (P = 0.05) in response to Step II but not to Step I dietary interventions. Positive correlations between changes in dietary total and saturated fatty acids and changes in TC and LDL and HDL cholesterol were observed (r = 0.59, 0.61, and 0.46, respectively; P < 0.001). Multiple regression analyses showed that for every 1% decrease in energy consumed as dietary saturated fatty acid, TC decreased by 0.056 mmol/L and LDL cholesterol by 0.05 mmol/L. Moreover, for every 1-kg decrease in body weight, triacylglycerol decreased by 0.011 mmol/L and HDL cholesterol increased by 0.011 mmol/L. Exercise resulted in greater decreases in TC, LDL cholesterol, and triacylglycerol and prevented the decrease in HDL cholesterol associated with low-fat diets. CONCLUSION: Step I and Step II dietary interventions have multiple beneficial effects on important cardiovascular disease risk factors.     

The effect of vigorous treadmill exercise on adipose tissue development in the Zucker rat

Four-week-old male lean and obese Zucker rats were subjected to intense daily exercise for a 10-week period. The exercise regimen used (running 6 days/week for 90 min/day on a treadmill at 1.3 Km/h at an 8 per cent grade) was designed to maximize the amount of exercise performed. Lean and obese runners (LR and OR) gained significantly less weight than sedentary controls (LS and OS). Food intake was lower in LR and unchanged in OR compared with control animals. Exercise increased adrenal weight in runners of both phenotypes. Gastrocnemius muscle weight was significantly higher in OR compared to OS. Despite the intense exercise regimen, carcass fat of OR was reduced only 12 per cent versus OS. In contrast, exercise decreased carcass fat by 32 per cent in LR versus LS. This decrease in body fat of LR was due to smaller adipocytes. Exercise did not affect adipocyte size in obese rats. However, OR had fewer carcass adipocytes. These results indicate that exercise had substantially different effects on adipose tissue cellularity of lean and obese rats. The results of the present study indicate that a program of intense treadmill exercise initiated immediately post weaning only modestly reduced adipose tissue growth in obese Zucker rats. Furthermore, it did not normalize body composition.     

An acid-stable insulin-like growth factor (IGF)-binding protein from pig serum inhibits binding of IGF-I and IGF-II to vascular endothelial cells

The effects of a porcine insulin-like growth factor (IGF)-binding protein on binding of IGF-I and IGF-II to porcine aortic endothelial cells (PAEC) were determined. Binding of 125I-labelled IGF-I and -II to IGF receptors was inhibited by IGF-binding protein. IGF-binding protein inhibited binding of IGF-I and -II in a dose-dependent manner with half-maximal inhibition occurring at 5.43 and 108 micrograms/l respectively. A 125I-labelled IGF-I--IGF-binding protein complex, formed by incubating 125I-labelled IGF-I with IGF-binding protein overnight at 4 degrees C, did not effectively bind to endothelial IGF receptors. Addition of IGF-binding protein to PAEC previously incubated with IGF-I caused a marked dissociation of bound IGF-I (47% dissociation within 12h). These results indicate that the acid-stable IGF-binding protein which appears to be a part of the 150 kDa GH-dependent binding protein, blocks binding of IGF-I and -II by the IGF receptors and appears to exhibit a higher affinity for IGF-I than the endothelial type-I IGF receptor. The ramifications of this latter point with respect to transfer of circulating IGFs (bound to their IGF-binding proteins) across the vascular endothelium are not clear.     

Effects of porcine growth hormone and insulin-like growth factor-I (IGF-I) on immunoreactive IGF-binding protein concentration in pigs

A specific radioimmunoassay (RIA) was established for an acid-stable insulin-like growth factor-binding protein (IGF-BP) isolated from porcine serum. The RIA recognizes a GH-dependent 150 kDa protein in porcine serum; therefore we postulate that the acid-stable IGF-BP is a component of the high molecular weight IGF-BP in porcine serum. The IGF-BP concentration was assayed in porcine serum (normal, 2.44 mg/l; hypophysectomized, 0.83 mg/l; serum from a GH-treated pig, 4.72 mg/l), porcine colostrum (2.55 mg/l), milk (0.91 mg/l), and amniotic (1.82-3.14 mg/l), allantoic (2.94-3.58 mg/l) and follicular (2.28 mg/l) fluids. Serum concentrations of IGF-BP were significantly increased (63%) in pigs chronically injected with porcine GH (pGH) (70 micrograms/kg body weight per day for 17 days). Concentrations of IGF-BP did not change in porcine serum following acute challenges with pGH (10-1000 micrograms/kg body weight) or IGF-I (4 or 8 mg per pig). This is the first report of a specific RIA for the porcine GH-dependent IGF-BP. Our results indicate that this IGF-BP is found in a wide variety of biological fluids and that its concentration appears to be regulated by pGH but not by IGF-I.     

Antagonism of insulin action in cultured pig adipose tissue by pituitary and recombinant porcine growth hormone: potentiation by hydrocortisone

The effects of physiological levels of pituitary porcine GH (ppGH) and recombinant pGH (rpGH) on lipogenesis in pig adipose tissue incubated with insulin and hydrocortisone (HC) were measured in short term (2-h) incubations and after long term culture (50 h). HC (50 ng/ml) had no effect on lipogenesis in 2-h incubations; however, HC and insulin (10 ng/ml) maintained the lipogenic capacity of cultured tissue at rates comparable to those in fresh adipose tissue. Neither ppGH nor rpGH (1 and 10 ng/ml, respectively) had any effect in short term incubations. After 50 h of culture, ppGH and rpGH both directly antagonized the ability of insulin to maintain lipogenesis; however, this antagonism was markedly enhanced by HC. The present study is the first to demonstrate a direct antagonism of insulin action by ppGH and rpGH in pig adipose tissue, and a marked potentiation of this antagonism by HC. This intrinsic property of pGH may account, in part, for the decrease in adipose tissue growth rates in pigs treated chronically with pGH.     

The Reliable Digit Span Test in Chronic Pain: Classification Accuracy in Detecting Malingered Pain-Related Disability

This study used criterion groups validation (known-groups design) to examine the classification accuracy of the Reliable Digit Span test (RDS) in a large group of chronic pain patients referred for psychological evaluation. The sample consisted of 612 patients classified into one of six groups based on evidence of malingered pain-related disability (MPRD): No-Incentive, Not MPRD; Incentive-Only, Not MPRD; Indeterminate; Possible MPRD; Probable MPRD; Definite MPRD. A total of 30 college student simulators were also included. Lower average RDS scores and higher rates of RDS failure were seen in patients classified as MPRD and in simulators. Consistent with previous literature in a variety of populations, RDS < = 6 provided the most accurate differentiation between MPRD and non-MPRD pain patients. Clinical implications are discussed.     

Abnormal dynamic functional connectivity is linked to recovery after acute ischemic stroke

The aim of the current study was to explore the whole‐brain dynamic functional connectivity patterns in acute ischemic stroke (AIS) patients and their relation to short and long‐term stroke severity. We investigated resting‐state functional MRI‐based dynamic functional connectivity of 41 AIS patients two to five days after symptom onset. Re‐occurring dynamic connectivity configurations were obtained using a sliding window approach and k‐means clustering. We evaluated differences in dynamic patterns between three NIHSS‐stroke severity defined groups (mildly, moderately, and severely affected patients). Furthermore, we built Bayesian hierarchical models to evaluate the predictive capacity of dynamic connectivity and examine the interrelation with clinical measures, such as white matter hyperintensity lesions. Finally, we established correlation analyses between dynamic connectivity and AIS severity as well as 90‐day neurological recovery (ΔNIHSS). We identified three distinct dynamic connectivity configurations acutely post‐stroke. More severely affected patients spent significantly more time in a configuration that was characterized by particularly strong connectivity and isolated processing of functional brain domains (three‐level ANOVA: p < .05, post hoc t tests: p < .05, FDR‐corrected). Configuration‐specific time estimates possessed predictive capacity of stroke severity in addition to the one of clinical measures. Recovery, as indexed by the realized change of the NIHSS over time, was significantly linked to the dynamic connectivity between bilateral intraparietal lobule and left angular gyrus (Pearson''s r = −.68, p = .003, FDR‐corrected). Our findings demonstrate transiently increased isolated information processing in multiple functional domains in case of severe AIS. Dynamic connectivity involving default mode network components significantly correlated with recovery in the first 3 months poststroke.     

An Association between Asthma and BMI in Adolescents: Results from the California Healthy Kids Survey

We examined the relationship between asthma prevalence and BMI in a cross-sectional survey of 471,969 adolescents. The size of the survey allowed us to investigate this relationship with much greater resolution than previously possible. Both lifetime and current asthma prevalence increased monotonically with increasing BMI, starting with individuals as low as the 45th to 55th percentiles of BMI. The pattern was similar between males and females and among six racial/ethnic groups. The results suggest that weight reduction even among persons not classified as overweight or obese may be an important component of asthma management.