Determining the Suitability of Registries for Embedding Clinical Trials in the United States: A Project of the Clinical Trials Transformation Initiative.

BACKGROUND: Patient registries are organized systems that use observational methods to collect uniform data on specified outcomes in a population defined by a particular disease, condition, or exposure. Data collected in registries often coincide with data that could support clinical trials. Integrating clinical trials within registries to create registry-embedded clinical trials offers opportunities to reduce duplicative data collection, identify and recruit patients more efficiently, decrease time to database lock, accelerate time to regulatory decision-making, and reduce clinical trial costs. This article describes a project of the Clinical Trials Transformation Initiative (CTTI) intended to help clinical trials researchers determine when a registry could potentially serve as the platform for the conduct of a clinical trial. METHODS: Through a review of registry-embedded clinical trials and commentaries, semi-structured interviews with experts, and a multi-stakeholder expert meeting, the project team addressed how to identify and describe essential registry characteristics, practices, and processes required to for conducting embedded clinical trials intended for regulatory submissions in the United States. RESULTS: Recommendations, suggested practices, and decision trees that facilitate the assessment of whether a registry is suitable for embedding clinical trials were developed, as well as considerations for the design of new registries. Essential registry characteristics include relevancy, robustness, reliability, and assurance of patient protections. CONCLUSIONS: The project identifies a clear role for registries in creating a sustainable and reusable infrastructure to conduct clinical trials. Adoption of these recommendations will facilitate the ability to perform high-quality and efficient prospective registry-based clinical trials.

Methods and Issues to Consider for Detection of Safety Signals From Spontaneous Reporting Databases: A Report of the DIA Bayesian Safety Signal Detection Working Group.

Spontaneous reporting (SR) adverse event system databases, large observational databases, large clinical trials, and large health records databases comprise repositories of information that may be useful for early detection of potential harms associated with drugs, devices, and vaccines. All of the data sources include many different adverse events and many medical products, so that any approach designed to detect "important" signals of potential harm must have adequate specificity to protect against false alarms yet provide satisfactory sensitivity for detecting issues that really need further investigation. Algorithms for evaluating potential risks using information from these sources, especially SR databases, have been described in the literature. The algorithms may seek to identify potential product-event associations without any prior specifications, to identify events associated with a particular product or set of products, or to identify products associated with a particular event or set of events. This article provides recommendations for using information from postmarketing spontaneous adverse event reporting databases to provide insight into risks of potential harm expressed by safety signals and offers guidance regarding appropriate methods, both frequentist and Bayesian, to use in various situations as a function of the objective of the analysis.

Recent Statistical Contributions to Medical Device Development.

Clinical trials in the development of new medical device products are in many ways analogous to clinical trials in the development of new drug or biologic products. However, the differences are important and not always intuitive to a statistician with only experience supporting development of drug and biologic products. In this paper we discuss some of the interesting differences with focus on the statistical innovation that is coming out of the medical device area. We discuss examples of the differences in clinical trial design and effects of these differences on clinical development programs.

Semiparametric Bayesian commensurate survival model for post-market medical device surveillance with non-exchangeable historical data.

Trial investigators often have a primary interest in the estimation of the survival curve in a population for which there exists acceptable historical information from which to borrow strength. However, borrowing strength from a historical trial that is non-exchangeable with the current trial can result in biased conclusions. In this article we propose a fully Bayesian semiparametric method for the purpose of attenuating bias and increasing efficiency when jointly modeling time-to-event data from two possibly non-exchangeable sources of information. We illustrate the mechanics of our methods by applying them to a pair of post-market surveillance datasets regarding adverse events in persons on dialysis that had either a bare metal or drug-eluting stent implanted during a cardiac revascularization surgery. We finish with a discussion of the advantages and limitations of this approach to evidence synthesis, as well as directions for future work in this area. The article's Supplementary Materials offer simulations to show our procedure's bias, mean squared error, and coverage probability properties in a variety of settings.

Bayesian adaptive design for device surveillance.

BACKGROUND: Postmarket device surveillance studies often have important primary objectives tied to estimating a survival function at some future time $$T$$ with a certain amount of precision. PURPOSE: This article presents the details and various operating characteristics of a Bayesian adaptive design for device surveillance, as well as a method for estimating a sample size vector (determined by the maximum sample size and a preset number of interim looks) that will deliver the desired power. METHODS: We adopt a Bayesian adaptive framework, which recognizes the fact that persons enrolled in a study report their results over time, not all at once. At each interim look, we assess whether we expect to achieve our goals with only the current group or the achievement of such goals is extremely unlikely even for the maximum sample size. RESULTS: Our Bayesian adaptive design can outperform two nonadaptive frequentist methods currently recommended by Food and Drug Administration (FDA) guidance documents in many settings. LIMITATIONS: Our method's performance can be sensitive to model misspecification and changes in the trial's enrollment rate. CONCLUSIONS: The proposed design provides a more efficient framework for conducting postmarket surveillance of medical devices.

Longitudinal inspiratory capacity changes in chronic obstructive pulmonary disease.

BACKGROUND: The changes in inspiratory capacity (IC) over time in chronic obstructive pulmonary disease (COPD) patients are unknown. The Understanding Potential Long-term Impacts on Function with Tiotropium (UPLIFT®) trial included IC measurements. METHODS: IC analysis from UPLIFT® (N = 5992) was performed at 1 and 6 months, and every 6 months through 4 years. Annualized rate of decline in pre- and post-bronchodilator IC and mean differences at each time point were analyzed by mixed-effects models. The relationships between baseline IC and exacerbation rate and mortality were explored using Cox regression analysis. RESULTS: Baseline characteristics: age, 65 years; 75% men; post-bronchodilator forced expiratory volume in 1 second, 1.32 L (48% predicted); pre- and post-bronchodilator IC, 2.03 and 2.33 L. Mean IC rate of decline (mL/year) was 34 ± 2 (1.7% of baseline) and 50 ± 3 (2.1% of baseline) pre- and post-bronchodilator, respectively, without significant between-group differences. Morning pre-bronchodilator (trough) IC improved with tiotropium versus placebo: 124 mL (1 month), 103 mL (1 year), 107 mL (2 years), 98 mL (3 years), and 97 mL (4 years) (all p < 0.001). Post-bronchodilator improvements were similar between treatment groups. Lower baseline IC values were associated with reduced time to first exacerbation. For the lowest quartile (n = 1413) the values in months were 14.3 (11.7-17.0) for tiotropium and 10.3 (8.8-11.7) for controls (p < 0.01). CONCLUSION: IC declines from approximately 34 to 50 mL/year in patients with stage II to IV COPD. Tiotropium treatment does not change the IC decline rate but provides 24-hour improvements in IC sustained over the long term. Trough IC differences suggest that tiotropium provides sustained decrease in end-expiratory lung volume.

Efficacy of tiotropium in COPD patients with FEV1 ≥ 60% participating in the UPLIFT® trial.

GOLD stage II COPD encompasses patients with FEV1 50-80% predicted. A published trials review suggested that benefits of maintenance therapy are limited to patients with FEV1 <60% predicted. We previously reported data demonstrating the efficacy of tiotropium in GOLD stage II disease in the 4-year UPLIFT® trial, and present here a further analysis of a sub-category of GOLD stage II patients with post-bronchodilator FEV1 ≥60% predicted from UPLIFT®. Outcomes included pre- and post-bronchodilator spirometry, exacerbations, SGRQ and mortality. Of the 5,992 UPLIFT® cohort, 1,210 (632 tiotropium, 578 control) had baseline post-bronchodilator FEV1 ≥60% predicted (range 60-78%), mean age was 64 years, 70% were men, and mean SGRQ total score was 39.9 units. Mean annual rate of post-bronchodilator FEV1 decline was 41 (tiotropium) and 49 (control) mL/year (P = 0.07); corresponding pre-bronchodilator values were 32 and 37 mL/year (P = 0.24). Morning pre-drug FEV1 and FVC improvements for tiotropium versus control were 87-127 mL and 139-186 ml, respectively (P < 0.001, all time-points). SGRQ total score improvements (tiotropium-control) were 2.0-3.4 units (P < 0.05 for all); a higher percentage of patients had an improvement of ≥4 units with tiotropium (P <0.05). Tiotropium reduced risk for an exacerbation (HR [95% CI] = 0.83 [0.71, 0.96]) and mortality for the 4-year protocol-defined treatment period (HR [95% CI] = 0.66 [0.45, 0.96]). Tiotropium treatment provides clinical efficacy in patients with GOLD stage II disease with an FEV1 ≥60% predicted, supporting current GOLD guidelines for COPD treatment. (ClinicalTrials.gov number NCT00144339).

Premature discontinuation during the UPLIFT study.

RATIONALE: Placebo-controlled clinical trials on COPD are characterized by premature discontinuation. At present, no clear insight into this phenomenon is available. OBJECTIVE: To obtain better insight into the phenomenon of premature discontinuation. METHODS: We analyzed the pattern of discontinuation in the UPLIFT-trial. MEASUREMENTS AND MAIN RESULTS: Premature discontinuation was substantial and greater in the placebo than in the tiotropium group (45 vs. 37%, p < 0.001). Patients discontinuing were characterized by more severe COPD (p < 0.0001), greater number of pack years (p < 0.002), smaller pre-bronchodilator and post-bronchodilator FEV(1) (p < 0.0001 for both), and worse SGRQ scores (p < 0.0001). Rates of decline of FEV(1) and SGRQ were greater in non-completers (p < 0.0001 for both). The latter differences increased over time indicating that the evolution of variables in time was related to trial completion. The risks of exacerbations and hospitalizations were greater in non-completers. In logistic regression analysis BMI, post-bronchodilator FEV(1), male gender and treatment with tiotropium were positively related to trial completion, whereas age, worse SGRQ, female gender, current smoking and assignment to the placebo group were negatively related. CONCLUSION: Assignment to the control group is related to premature discontinuation. Discontinuation was important and selective in this large trial. Pulmonary function, health-related quality of life and smoking are the most important other variables related to discontinuation. The evolution of variables during the trial is also related to discontinuation. Complete follow-up of discontinued patients may provide better insight into the efficacy of medication in future trials.

Preliminary report: Zn-alpha2-glycoprotein genotype and serum levels are associated with serum lipids.

Zn-alpha2-glycoprotein (ZAG) is a serum protein implicated in cancer cachexia and lipolysis. Our aim was to investigate serum levels of ZAG and polymorphisms in the ZAG gene in relation to serum lipids in man. Serum levels of ZAG correlated with serum levels of cholesterol (P = .00088) in healthy subjects and during weight loss (P = .059). The ZAG genotype was associated with total cholesterol (P = .014) and low-density lipoprotein cholesterol (P = .026) in healthy subjects, and the associations were replicated in an additional cohort (P = .0017 and P = .060, respectively). Our data indicate that ZAG plays a role in lipid metabolism.

Effect of tiotropium on outcomes in patients with moderate chronic obstructive pulmonary disease (UPLIFT): a prespecified subgroup analysis of a randomised controlled trial.

BACKGROUND: The beneficial effects of pharmacotherapy for chronic obstructive pulmonary disease (COPD) are well established. However, there are few data for treatment in the early stages of the disease. We examined the effect of tiotropium on outcomes in a large subgroup of patients with moderate COPD. METHODS: The Understanding Potential Long-Term Impacts on Function with Tiotropium (UPLIFT) study was a randomised, double-blind, placebo-controlled trial undertaken in 487 centres in 37 countries. 5993 patients aged 40 years or more with COPD were randomly assigned to receive 4 years of treatment with either once daily tiotropium (18 microg; n=2987) or matching placebo (n=3006), delivered by an inhalation device. Randomisation was by computer-generated blocks of four, with stratification according to study site. In a prespecified subgroup analysis, we investigated the effects of tiotropium in patients with Global Initiative for Chronic Obstructive Lung Disease (GOLD) stage II disease. Primary endpoints were the yearly rates of decline in prebronchodilator forced expiratory volume in 1 s (FEV(1)) and in postbronchodilator FEV(1), beginning on day 30 until completion of double-blind treatment. The analysis included all patients who had at least three measurements of pulmonary function. This study is registered with ClinicalTrials.gov, number NCT00144339. FINDINGS: 2739 participants (mean age 64 years [SD 9]) had GOLD stage II disease at randomisation (tiotropium, n=1384; control, n=1355), with a mean postbronchodilator FEV(1) of 1.63 L (SD 0.37; 59% of predicted value). 1218 patients in the tiotropium group and 1157 in the control group had three or more measurements of postbronchodilator pulmonary function after day 30 and were included in the analysis. The rate of decline of mean postbronchodilator FEV(1) was lower in the tiotropium group than in the control group (43 mL per year [SE 2] vs 49 mL per year [SE 2], p=0.024). For prebronchodilator pulmonary function, 1221 patients in the tiotropium group and 1158 in the control group had three or more measurements and were included in the analysis. The rate of decline of mean prebronchodilator FEV(1) did not differ between groups (35 mL per year [SE 2] vs 37 mL per year [SE 2]; p=0.38). Health status, measured with the St George's Respiratory Questionnaire, was better at all timepoints in the tiotropium group than in the control group (p

Acute hyperinsulinemia raises plasma interleukin-6 in both nondiabetic and type 2 diabetes mellitus subjects, and this effect is inversely associated with body mass index.

Hyperinsulinemia is a characteristic of type 2 diabetes mellitus (T2DM) and is believed to play a role in the low-grade inflammation seen in T2DM. The main aim was to study the effect of hyperinsulinemia on adipokines in individuals with different levels of insulin resistance, glycemia, and obesity. Three groups of sex-matched subjects were studied: young healthy subjects (YS; n = 10; mean age, 26 years; body mass index [BMI], 22 kg/m(2)), patients with T2DM (DS; n = 10; 61 years; BMI, 27 kg/m(2)), and age- and BMI-matched controls to DS (CS; n = 10; 60 years; BMI, 27 kg/m(2)). Plasma concentrations of adipokines were measured during a hyperinsulinemic euglycemic clamp lasting 4 hours. Moreover, insulin-stimulated glucose uptake in isolated adipocytes was analyzed to address adipose tissue insulin sensitivity. Plasma interleukin (IL)-6 increased significantly (P < or = .01) in all 3 groups during hyperinsulinemia. However, the increase was smaller in both DS (P = .06) and CS (P < .05) compared with YS (approximately 2.5-fold vs approximately 4-fold). A significant increase of plasma tumor necrosis factor (TNF) alpha was observed only in YS. There were only minor or inconsistent effects on adiponectin, leptin, and high-sensitivity C-reactive protein levels during hyperinsulinemia. Insulin-induced rise in IL-6 correlated negatively to BMI (P = .001), waist to hip ratio (P = .05), and baseline (fasting) insulin (P = .03) and IL-6 (P = .02) levels and positively to insulin-stimulated glucose uptake in isolated adipocytes (P = .07). There was no association with age or insulin sensitivity. In a multivariate analysis, also including T2DM/no T2DM, an independent correlation (inverse) was found only between BMI and fold change of IL-6 (r(2) = 0.41 for model, P < .005). Hyperinsulinemia per se can produce an increase in plasma IL-6 and TNFalpha, and this can potentially contribute to the low-grade inflammation seen in obesity and T2DM. However, obesity seems to attenuate the ability of an acute increase in insulin to further raise circulating levels of IL-6 and possibly TNFalpha.

Cell death-inducing DFF45-like effector C is reduced by caloric restriction and regulates adipocyte lipid metabolism.

Members of the cell death-inducing DFF45-like effector (CIDE) gene family have been shown to regulate lipid metabolism. In this article, we report that the third member of the human CIDE family, CIDEC, is down-regulated in response to a reduced caloric intake. The down-regulation was demonstrated by microarray and real-time polymerase chain reaction analysis of subcutaneous adipose tissue in 2 independent studies on obese patients undergoing treatment with a very low calorie diet. By analysis of CIDEC expression in 65 human tissues, we conclude that human CIDEC is predominantly expressed in subcutaneous adipocytes. Together, these observations led us to investigate the effect of decreased CIDEC expression in cultured 3T3-L1 adipocytes. Small interfering RNA-mediated knockdown of CIDEC resulted in an increased basal release of nonesterified fatty acids, decreased responsiveness to adrenergic stimulation of lipolysis, and increased oxidation of endogenous fatty acids. Thus, we suggest that CIDEC is a regulator of adipocyte lipid metabolism and may be important for the adipocyte to adapt to changes in energy availability.

Relations of adipose tissue CIDEA gene expression to basal metabolic rate, energy restriction, and obesity: population-based and dietary intervention studies.

CONTEXT: Cell death-inducing DNA fragmentation factor-alpha-like effector A (CIDEA) could be a potential target for the treatment of obesity via the modulation of metabolic rate, based on the findings that CIDEA inhibits the brown adipose tissue uncoupling process in rodents. OBJECTIVES: Our objects were to investigate the putative link between CIDEA and basal metabolic rate in humans and to elucidate further the role of CIDEA in human obesity. DESIGN: We have explored CIDEA gene expression in adipose tissue in two different human studies: a cross-sectional and population-based study assessing body composition and metabolic rate (Mölndal Metabolic study, n = 92); and a longitudinal intervention study of obese subjects treated with a very low calorie diet (VLCD) (VLCD study, n = 24). RESULTS: The CIDEA gene was predominantly expressed in adipocytes as compared with other human tissues. CIDEA gene expression in adipose tissue was inversely associated with basal metabolic rate independently of body composition, age, and gender (P = 0.014). The VLCD induced an increase in adipose tissue CIDEA expression (P < 0.0001) with a subsequent decrease in response to refeeding (P < 0.0001). Reduced CIDEA gene expression was associated with a high body fat content (P < 0.0001) and high insulin levels (P < 0.01). No dysregulation of CIDEA expression was observed in individuals with the metabolic syndrome when compared with body mass index-matched controls. In a separate sample of VLCD-treated subjects (n = 10), uncoupling protein 1 expression was reduced during diet (P = 0.0026) and inversely associated with CIDEA expression (P = 0.0014). CONCLUSION: The findings are consistent with the concept that CIDEA plays a role in adipose tissue energy expenditure.

Postnatal testosterone exposure results in insulin resistance, enlarged mesenteric adipocytes, and an atherogenic lipid profile in adult female rats: comparisons with estradiol and dihydrotestosterone.

Postnatal events contribute to features of the metabolic syndrome in adulthood. In this study, postnatally administered testosterone reduced insulin sensitivity and increased the mesenteric fat depot, the size of mesenteric adipocytes, serum levels of total cholesterol, low-density lipoprotein cholesterol, and triglycerides, and the atherogenic index in adult female rats. To assess the involvement of estrogen and androgen receptors in these programming effects, we compared testosterone-exposed rats to rats exposed to estradiol or dihydrotestosterone (DHT). Estradiol-treated rats had lower insulin sensitivity than testosterone-treated rats and, like those rats, had enlarged mesenteric adipocytes and increased triglyceride levels. DHT also reduced insulin sensitivity but did not mimic the other metabolic effects of testosterone. All treated rats were probably anovulatory, but only those treated with testosterone had reduced testosterone levels. This study confirms our previous finding that postnatal administration of testosterone reduces insulin sensitivity in adult female rats and shows that this effect is accompanied by unfavorable changes in mesenteric fat tissue and in serum lipid levels. The findings in the estradiol and DHT groups suggest that estrogen receptors exert stronger metabolic programming effects than androgen receptors. Thus, insults such as sex hormone exposure in early life may have long-lasting effects, thereby creating a predisposition to disturbances in insulin sensitivity, adipose tissue, and lipid profile in adulthood.

Dissociation between adipose tissue expression and serum levels of adiponectin during and after diet-induced weight loss in obese subjects with and without the metabolic syndrome.

The study aimed to examine if dysmetabolic subjects (MetS+) have lower adiponectin gene expression and lower circulating adiponectin levels than non-dysmetabolic obese subjects (MetS-) at baseline, if adiponectin expression and adiponectin concentration rise more in the dysmetabolic group during weight loss, and if v-SNARE Vti1a (vesicle transport soluble NSF attachment protein receptor vps10p tail interacting 1a) expression increases during the weight loss, as a mechanism for increased adiponectin secretion. Twenty-one obese MetS+ and 19 obese MetS- subjects underwent a very low-energy diet for 16 weeks followed by 2 weeks of refeeding. Abdominal subcutaneous adipose tissue biopsies and blood samples were taken before, during, and after dieting for DNA microarray, reverse transcriptase-polymerase chain reaction, and biochemical analyses. Serum adiponectin was also assessed in a sex- and age-matched healthy, nonobese reference group. Weight decreased by 26.3+/-9.8 kg in the MetS+ group and 28.2+/-8.4 kg in the MetS- group with concomitant reductions in insulin, hemoglobin A1c, and triglycerides that were more pronounced in the MetS+ group. Initially, the MetS+ subjects had lower serum adiponectin, but the differences disappeared at week 8, with a continuous increase in serum adiponectin throughout the study in both groups to a level that was higher than in the reference group. The expression of adiponectin and v-SNARE Vti1a did not differ between the groups or over time. In conclusion, obese subjects with the metabolic syndrome had lower circulating adiponectin than subjects without the syndrome. Weight loss increased serum levels of adiponectin without a parallel increase in adiponectin gene expression. The mechanisms involved in the regulation of adiponectin levels merits further investigation.

A new rat model exhibiting both ovarian and metabolic characteristics of polycystic ovary syndrome.

Polycystic ovary syndrome (PCOS) is a complex endocrine and metabolic disorder associated with ovulatory dysfunction, hyperandrogenism, abdominal obesity, and insulin resistance. However, its etiology is unclear, and its management is often unsatisfactory or requires a diversified approach. Here, we describe a new rat PCOS model, the first to exhibit both ovarian and metabolic characteristics of the syndrome. Female rats received the nonaromatizable androgen dihydrotestosterone (DHT) or the aromatase inhibitor letrozole by continuous administration, beginning before puberty, to activate androgen receptors. Adult DHT rats had irregular cycles, polycystic ovaries characterized by cysts formed from atretic follicles, and a diminished granulosa layer. They also displayed metabolic features, including increased body weight, increased body fat, and enlarged mesenteric adipocytes, as well as elevated leptin levels and insulin resistance. All letrozole rats were anovulatory and developed polycystic ovaries with structural changes strikingly similar to those in human PCOS. Our findings suggest that the formation of a "hyperplastic" theca interna reflects the inclusion of luteinized granulosa cells in the cyst wall rather than true hyperplasia. We conclude that the letrozole model is suitable for studies of the ovarian features of human PCOS, while the DHT model is suitable for studies of both ovarian and metabolic features of the syndrome.

The expression of NAD(P)H:quinone oxidoreductase 1 is high in human adipose tissue, reduced by weight loss, and correlates with adiposity, insulin sensitivity, and markers of liver dysfunction.

CONTEXT: We have previously identified nicotinamide adenine dinucleotide phosphate:quinone oxidoreductase 1 (NQO1), an enzyme involved in the protection against oxidative stress, as a gene predominantly expressed in human adipocytes. Studies in mice deficient in NQO1 activity suggest that NQO1 may also play an important role in metabolism. OBJECTIVE: The aim of this study was to explore the expression and regulation of NQO1 in human adipose tissue (AT) and isolated adipocytes. PATIENTS AND RESULTS: The high expression of NQO1 in adipocytes was verified in human adipocytes and AT by real-time PCR. DNA microarray analysis showed that NQO1 was expressed at higher levels in large compared with small adipocytes, isolated from the same fat biopsy. Furthermore, NQO1 mRNA levels were positively correlated with adipocyte size (n = 7; P < 0.002). During an 18-wk diet regime (n = 24; mean weight loss 27 kg), the NQO1 expression in human sc AT was down-regulated (P < 0.0001), and mRNA levels correlated with body mass index (P = 0.0005), sc, and total abdominal AT areas, as determined by computerized tomography (P < 0.0001, both) and metabolic parameters. NQO1 mRNA levels were also positively correlated with aspartate aminotransferase (P = 0.0028) and alanine aminotransferase (P = 0.0219), markers known to be associated with severity of hepatic steatosis. CONCLUSIONS: NQO1 is highly expressed in human AT, particularly in large adipocytes. AT NQO1 expression is reduced during diet-induced weight loss, and the expression levels positively correlate with adiposity, glucose tolerance, and markers of liver dysfunction. Together, these findings indicate a role for NQO1 in the metabolic complications of human obesity.

Separation of human adipocytes by size: hypertrophic fat cells display distinct gene expression.

Enlarged adipocytes are associated with insulin resistance and are an independent predictor of type 2 diabetes. To understand the molecular link between these diseases and adipocyte hypertrophy, we developed a technique to separate human adipocytes from an adipose tissue sample into populations of small cells (mean 57.6+/-3.54 microm) and large cells (mean 100.1+/-3.94 microm). Microarray analysis of the cell populations separated from adipose tissue from three subjects identified 14 genes, of which five immune-related, with more than fourfold higher expression in large cells than small cells. Two of these genes were serum amyloid A (SAA) and transmembrane 4 L six family member 1 (TM4SF1). Real-time RT-PCR analysis of SAA and TM4SF1 expression in adipocytes from seven subjects revealed 19-fold and 22-fold higher expression in the large cells, respectively, and a correlation between adipocyte size and both SAA and TM4SF1 expression. The results were verified using immunohistochemistry. In comparison with 17 other human tissues and cell types by microarray, large adipocytes displayed by far the highest SAA and TM4SF1 expression. Thus, we have identified genes with markedly higher expression in large, compared with small, human adipocytes. These genes may link hypertrophic obesity to insulin resistance/type 2 diabetes.

The expression of inhibin beta B is high in human adipocytes, reduced by weight loss, and correlates to factors implicated in metabolic disease.

Adipose tissue is an endocrine organ that produces and secretes adipokines. The aim of this study was to identify genes predominantly expressed in human subcutaneous adipocytes. For this purpose, an algorithm was developed and DNA microarray expression profiles from 33 human tissues and cell types were used to select genes. Inhibin beta B (INHBB; coding for the activin betaB subunit) was identified and high expression in adipocytes was confirmed by real-time PCR and immunohistochemistry. INHBB expression in adipose tissue was down regulated by diet-induced weight loss (p<0.001). Furthermore, INHBB expression was positively correlated to total (p<0.001) and subcutaneous (p<0.01) adipose tissue areas and serum levels of fasting insulin (p<0.01) and cholesterol (p<0.05). In conclusion, INHBB expression was high in human adipocytes, reduced by weight loss and adipose tissue INHBB mRNA levels correlated to metabolic risk factors. This suggests that activin B produced in adipocytes may play a role in the metabolic syndrome.

Three definitions of the metabolic syndrome: relations to mortality and atherosclerotic morbidity.

BACKGROUND: Different definitions of the metabolic syndrome are used, and at least one of these does not include indices of glucose intolerance and/or insulin resistance as obligatory components. In this paper, we examine the predictive power of indices having and not having these obligatory components. METHODS: A total of 1135 men and women, aged 37-61 years, were randomly selected from the populations of Mölndal and Orebro, Sweden. Mortality rate and incidence of cardiovascular morbidity were analyzed in subjects with and without the metabolic syndrome according to the definitions of WHO (World Health Organization), EGIR (European Group for the study of Insulin Resistance), and ATPIII (Adult Treatment Panel-III Guidelines). Atherosclerotic morbidity was traced until December 2002 and mortality until December 2003. Due to lack of data, our WHO definition does not include information on micro-albuminuria. RESULTS: There were 17 deaths during the 3-8 year follow-up. As compared to subjects without the metabolic syndrome, all-cause mortality was increased significantly in subjects with the syndrome defined according to WHO(non u-alb) (hazards ratio [HR] 2.98, 95% CI 1.07, 8.28, p = 0.036) but not according to EGIR (HR 1.93, 95% CI 0.67, 5.55, p = 0.230) or ATPIII (HR 0.88, 95% CI 0.20, 3.89, p = 0.870). Incident cases of ischemic heart, cerebrovascular, and/or peripheral arterial disease (n = 18) were related to the metabolic syndrome according to WHO(non u-alb) and EGIR but not according to ATPIII. CONCLUSIONS: Inclusion of glucose intolerance and/or insulin resistance as obligatory criteria in the definition of the metabolic syndrome seems to be important for the ability to predict all-cause mortality and incident cardiovascular morbidity.