Detecting episomal or integrated human papillomavirus 16 DNA using an exonuclease V-qPCR-based assay.

Screening for human papillomavirus (HPV) integration into host cell chromosomes typically requires large amounts of time and reagents. We developed a rapid and sensitive assay based on exonuclease V (ExoV) and quantitative polymerase chain reaction (qPCR) to determine HPV genome configurations in cell lines and tissues. We established the assay using genomic DNA from cell lines known to harbor integrated or episomal HPV16. DNA was incubated with ExoV, which is specific for linear DNA, and the DNA fraction resistant to digestion was measured by qPCR. The percent of DNA resistant to ExoV digestion was calculated relative to undigested DNA for determination of episomal or integrated HPV16. The ExoV assay was accurate, capable of distinguishing episomal from integrated HPV16 in cell lines and tissues. Future applications of the ExoV assay may include screening of HPV genome configurations in the progression of HPV-associated cancers.

Inhibition of Epstein-Barr Virus Replication in Human Papillomavirus-Immortalized Keratinocytes.

Epstein-Barr virus (EBV) is implicated in the pathogenesis of human papillomavirus (HPV)-associated oropharyngeal squamous cell carcinoma (OSCC). EBV-associated cancers harbor a latent EBV infection characterized by a lack of viral replication and the expression of viral oncogenes. Cellular changes promoted by HPV are comparable to those shown to facilitate EBV latency, though whether HPV-positive cells support a latent EBV infection has not been demonstrated. Using a model of direct EBV infection into HPV16-immortalized tonsillar cells grown in organotypic raft culture, we showed robust EBV replication in HPV-negative rafts but little to no replication in HPV-immortalized rafts. The reduced EBV replication was independent of immortalization, as human telomerase-immortalized normal oral keratinocytes supported robust EBV replication. Furthermore, we observed reduced EBV lytic gene expression and increased expression of EBER1, a noncoding RNA highly expressed in latently infected cells, in the presence of HPV. The use of human foreskin keratinocyte rafts expressing the HPV16 E6 and/or E7 oncogene(s) (HPV E6 and E7 rafts) showed that E7 was sufficient to reduce EBV replication. EBV replication is dependent upon epithelial differentiation and the differentiation-dependent expression of the transcription factors KLF4 and PRDM1. While KLF4 and PRDM1 levels were unaltered, the expression levels of KLF4 transcriptional targets, including late differentiation markers, were reduced in HPV E6 and E7 rafts compared to their levels in parental rafts. However, the HPV E7-mediated block in EBV replication correlated with delayed expression of early differentiation markers. Overall, this study reveals an HPV16-mediated block in EBV replication, through E7, that may facilitate EBV latency and long-term persistence in the tumor context.IMPORTANCE Using a model examining the establishment of EBV infection in HPV-immortalized tissues, we showed an HPV-induced interruption of the normal EBV life cycle reminiscent of a latent EBV infection. Our data support the notion that a persistent EBV epithelial infection depends upon preexisting cellular alterations and suggest the ability of HPV to promote such changes. More importantly, these findings introduce a model for how EBV coinfection may influence HPV-positive (HPV-pos) OSCC pathogenesis. Latently EBV-infected epithelial cells, as well as other EBV-associated head-and-neck carcinomas, exhibit oncogenic phenotypes commonly seen in HPV-pos OSCC. Therefore, an HPV-induced shift in the EBV life cycle toward latency would not only facilitate EBV persistence but also provide additional viral oncogene expression, which can contribute to the rapid progression of HPV-pos OSCC. These findings provide a step toward defining a role for EBV as a cofactor in HPV-positive oropharyngeal tumors.

Epstein-Barr virus in the pathogenesis of oral cancers.

Epstein-Barr virus (EBV) is a ubiquitous gamma-herpesvirus that establishes a lifelong persistent infection in the oral cavity and is intermittently shed in the saliva. EBV exhibits a biphasic life cycle, supported by its dual tropism for B lymphocytes and epithelial cells, which allows the virus to be transmitted within oral lymphoid tissues. While infection is often benign, EBV is associated with a number of lymphomas and carcinomas that arise in the oral cavity and at other anatomical sites. Incomplete association of EBV in cancer has questioned if EBV is merely a passenger or a driver of the tumorigenic process. However, the ability of EBV to immortalize B cells and its prevalence in a subset of cancers has implicated EBV as a carcinogenic cofactor in cellular contexts where the viral life cycle is altered. In many cases, EBV likely acts as an agent of tumor progression rather than tumor initiation, conferring malignant phenotypes observed in EBV-positive cancers. Given that the oral cavity serves as the main site of EBV residence and transmission, here we review the prevalence of EBV in oral malignancies and the mechanisms by which EBV acts as an agent of tumor progression.

The interaction between human papillomavirus and other viruses.

The etiological role of human papillomavirus (HPV) in anogenital tract and head and neck cancers is well established. However, only a low percentage of HPV-positive women develop cancer, indicating that HPV is necessary but not sufficient in carcinogenesis. Several biological and environmental cofactors have been implicated in the development of HPV-associated carcinoma that include immune status, hormonal changes, parity, dietary habits, tobacco usage, and co-infection with other sexually transmissible agents. Such cofactors likely contribute to HPV persistent infection through diverse mechanisms related to immune control, efficiency of HPV infection, and influences on tumor initiation and progression. Conversely, HPV co-infection with other factors may also harbor anti-tumor effects. Here, we review epidemiological and experimental studies investigating human immunodeficiency virus (HIV), herpes simplex virus (HSV) 1 and 2, human cytomegalovirus (HCMV), Epstein-Barr virus (EBV), BK virus (BKV), JC virus (JCV), and adeno-associated virus (AAV) as viral cofactors in or therapeutic factors against the development of genital and oral HPV-associated carcinomas.

What is the best predictor of the atherogenic LDL subclass phenotype 'pattern B' in patients with type 2 diabetes mellitus?

BACKGROUND: The atherogenic lipoprotein phenotype 'pattern B' comprises a predominance of small-dense low-density lipoprotein (sdLDL). Gradient gel electrophoresis (GGE) is considered a 'gold standard' method for identifying this phenotype, but is impractical for routine laboratory use. The low-density lipoprotein cholesterol:apolipoprotein-B (LDL-C:Apo-B) ratio has been advocated as a surrogate marker for sdLDL and a direct assay for sdLDL has recently become available. We compared the sdLDL assay and LDL-C:Apo-B with more established lipid parameters to predict the presence of 'pattern B' phenotype. METHOD: Blood was collected from 97 fasted subjects on three separate occasions. Total cholesterol, triglyceride, Apo-B and sdLDL were measured; LDL- and HDL-cholesterol were determined after ultracentrifugation. The predominant LDL particle size and phenotype were assigned by GGE. RESULTS: 'Pattern B' phenotype was identified in 36% of samples. Peak particle size showed a positive correlation with HDL-cholesterol and a negative correlation with triglyceride and Apo-B. Receiver operating curve (ROC) analysis showed triglyceride:HDL-C ratio and triglyceride alone to be the best predictors of 'pattern B' phenotype, with area under the curve (AUC) being 0.87 and 0.84, respectively. AUCs for sdLDL (0.74) and LDL-C:Apo-B (0.71) were significantly lower (P < 0.05). A high sdLDL concentration had the greatest specificity (95%) and positive predictive value (74%) for 'pattern B' phenotype, but low sensitivity (43%). CONCLUSION: Direct measurement of sdLDL provided the most specific predictor of 'pattern B' phenotype, whereas triglyceride:HDL-C ratio or triglycerides alone, parameters readily available in most laboratories, were the best predictors by ROC analysis.

The fungicide ciclopirox inhibits lymphatic endothelial cell tube formation by suppressing VEGFR-3-mediated ERK signaling pathway.

Ciclopirox olamine (CPX), an off-patent antifungal agent used to treat mycoses of skin and nails, has recently been demonstrated to be a potential anticancer agent. However, the underlying mechanism is not well understood. Here, for the first time, we show that CPX inhibited lymphangiogenesis in an in vitro model (tube formation). This effect was, in part, associated with inhibition of vascular endothelial growth factor receptor-3 (VEGFR-3) expression, as overexpression of VEGFR-3 conferred partial resistance to CPX inhibitory effect on tube formation in lymphatic endothelial cells (LECs), whereas downregulation of VEGFR-3 mimicked the effect of CPX, blocking the tube formation. Further study revealed that CPX did not alter mRNA level, but inhibited protein synthesis and promoted protein degradation of VEGFR-3. In addition, we found that CPX inhibited phosphorylation of the extracellular signal-related kinase 1/2 (ERK1/2), a downstream effector of VEGFR-3. Overexpression of VEGFR-3 attenuated CPX inhibition of ERK1/2 phosphorylation, whereas downregulation of VEGFR-3 inhibited ERK1/2 phosphorylation in LECs. Ectopic expression of constitutively active mitogen-activated protein kinase kinase 1 (MKK1) resulted in activation of ERK1/2 and partially prevented CPX inhibition of LEC tube formation. The results suggest that CPX inhibits LEC tube formation at least, in part, through inhibiting VEGFR-3-mediated ERK signaling pathway.

Effects of fenofibrate on renal function in patients with type 2 diabetes mellitus: the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) Study.

AIMS/HYPOTHESIS: Fenofibrate caused an acute, sustained plasma creatinine increase in the Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) and Action to Control Cardiovascular Risk in Diabetes (ACCORD) studies. We assessed fenofibrate's renal effects overall and in a FIELD washout sub-study. METHODS: Type 2 diabetic patients (n = 9,795) aged 50 to 75 years were randomly assigned to fenofibrate (n = 4,895) or placebo (n = 4,900) for 5 years, after 6 weeks fenofibrate run-in. Albuminuria (urinary albumin/creatinine ratio measured at baseline, year 2 and close-out) and estimated GFR, measured four to six monthly according to the Modification of Diet in Renal Disease Study, were pre-specified endpoints. Plasma creatinine was re-measured 8 weeks after treatment cessation at close-out (washout sub-study, n = 661). Analysis was by intention-to-treat. RESULTS: During fenofibrate run-in, plasma creatinine increased by 10.0 µmol/l (p < 0.001), but quickly reversed on placebo assignment. It remained higher on fenofibrate than on placebo, but the chronic rise was slower (1.62 vs 1.89 µmol/l annually, p = 0.01), with less estimated GFR loss (1.19 vs 2.03 ml min(-1) 1.73 m(-2) annually, p < 0.001). After washout, estimated GFR had fallen less from baseline on fenofibrate (1.9 ml min(-1) 1.73 m(-2), p = 0.065) than on placebo (6.9 ml min(-1) 1.73 m(-2), p < 0.001), sparing 5.0 ml min(-1) 1.73 m(-2) (95% CI 2.3-7.7, p < 0.001). Greater preservation of estimated GFR with fenofibrate was observed with baseline hypertriacylglycerolaemia (n = 169 vs 491 without) alone, or combined with low HDL-cholesterol (n = 140 vs 520 without) and reductions of ≥ 0.48 mmol/l in triacylglycerol over the active run-in period (pre-randomisation) (n = 356 vs 303 without). Fenofibrate reduced urine albumin concentrations and hence albumin/creatinine ratio by 24% vs 11% (p < 0.001; mean difference 14% [95% CI 9-18]; p < 0.001), with 14% less progression and 18% more albuminuria regression (p < 0.001) than in participants on placebo. End-stage renal event frequency was similar (n = 21 vs 26, p = 0.48). CONCLUSIONS/INTERPRETATION: Fenofibrate reduced albuminuria and slowed estimated GFR loss over 5 years, despite initially and reversibly increasing plasma creatinine. Fenofibrate may delay albuminuria and GFR impairment in type 2 diabetes patients. Confirmatory studies are merited. TRIAL REGISTRATION: ISRCTN64783481.

Plasma sex hormone-binding globulin, corticosteroid-binding globulin, cortisol, and free cortisol levels in outpatients attending a lipid disorders clinic: a cross-sectional study of 1137 subjects.

We measured plasma sex hormone-binding globulin (SHBG), corticosteroid-binding globulin (CBG), and total cortisol, and calculated free plasma cortisol in 1 137 subjects attending a hospital outpatient lipid disorders clinic to investigate whether or not these analytes correlated with the degree of insulin resistance and the presence of the metabolic syndrome. In both males and females, plasma SHBG correlated inversely with anthropometric measures and with fasting glucose, insulin, insulin resistance, and triglycerides, and positively with HDL-cholesterol. However, in males with the metabolic syndrome, unlike females, the relationship between SHBG, some anthropometric measures, fasting glucose, insulin, and HDL-cholesterol were lost, which suggests that in males SHBG may not co-cluster with other components of the metabolic syndrome. In males and males with the metabolic syndrome, total plasma cortisol and calculated plasma free cortisol correlated positively with fasting glucose. Corticosteroid-binding globulin correlated inversely with percentage body fat and positively with HDL-cholesterol in males with and without the metabolic syndrome. CBG correlated negatively with age in both sexes. Overall, the results confirm the finding that SHBG is a marker of insulin resistance in males and females and that SHBG is associated with fasting triglycerides in males with the metabolic syndrome. Importantly, SHBG could be considered a stronger component of the metabolic syndrome in females than in males. However, the aetiological role of CBG and cortisol in insulin resistance is uncertain, although in males, cortisol and CBG could be subtly related to the degree of insulin resistance.

Comparison of indices of insulin resistance with metabolic syndrome classifications to predict the development of impaired fasting glucose in overweight and obese subjects: a 3-year prospective study.

OBJECTIVE: To compare the ability of biochemical indices of insulin resistance (IR) with metabolic syndrome (MetS) classifications to predict changes in blood glucose control over a 3-year period in overweight and obese subjects. DESIGN: This was a longitudinal, prospective study, with data collected at baseline, 18 and 36 months. SUBJECTS AND METHODS: A total of 175 overweight (body mass index (BMI)>25 kg m(-2)) and obese (BMI>30 kg m(-2)) subjects were enrolled in the study. The IR indices assessed included fasting insulin concentration, the insulin/glucose-derived indices, homeostasis assessment model of insulin resistance (HOMA-IR) and quantitative insulin sensitivity check index (QUICKI), the insulin/triglyceride-derived McAuley index, plasma adiponectin concentration and the triglyceride (trig) and high-density lipoprotein (HDL)-cholesterol ratio (trig:HDL). The two MetS classifications were assessed according to the definitions of the National Cholesterol Education Program-Third Adult Treatment Panel (NCEP-ATPIII) and the International Diabetes Federation (IDF). The potential of the IR indices and MetS classifications at baseline to predict the development of impaired fasting glucose (IFG) was examined using receiver-operator characteristic (ROC) curve analysis and analysis of variance. RESULTS: Complete data were collected on 158 subjects. In all, 51 (32%) subjects developed IFG during the study. The analysis of variance showed significant differences between the IFG and normoglycaemic group in the baseline values of the McAuley index, trig:HDL, plasma adiponectin concentration and prevalence of the MetS. The ROC curve analysis confirmed this result and showed that the strongest predictors of IFG were baseline trig:HDL and IDF MetS classification, followed in order by the McAuley index, plasma adiponectin concentration and NCEP-ATPIII MetS classification. In contrast, the baseline values of fasting insulin, HOMA-IR and QUICKI did not predict IFG. DISCUSSION: This study showed that the IR indices, derived, in part, from plasma triglyceride concentration, were sensitive predictors for the development of IFG in normoglycaemic overweight and obese subjects. Indices derived from glucose and insulin did not identify this at-risk group. The study also showed that the presence of MetS and its abnormalities of an increased trig:HDL ratio and low plasma adiponectin concentration were all sensitive predictors of IFG.

Dental microwear texture analysis of two families of subfossil lemurs from Madagascar.

This study employs dental microwear texture analysis to reconstruct the diets of two families of subfossil lemurs from Madagascar, the archaeolemurids and megaladapids. This technique is based on three-dimensional surface measurements utilizing a white-light confocal profiler and scale-sensitive fractal analysis. Data were recorded for six texture variables previously used successfully to distinguish between living primates with known dietary differences. Statistical analyses revealed that the archaeolemurids and megaladapids have overlapping microwear texture signatures, suggesting that the two families occasionally depended on resources with similar mechanical properties. Even so, moderate variation in most attributes is evident, and results suggest potential differences in the foods consumed by the two families. The microwear pattern for the megaladapids indicates a preference for tougher foods, such as many leaves, while that of the archaeolemurids is consistent with the consumption of harder foods. The results also indicate some intraspecific differences among taxa within each family. This evidence suggests that the archaeolemurids and megaladapids, like many living primates, likely consumed a variety of food types.

Plasma levels of sex hormone-binding globulin, corticosteroid-binding globulin and cortisol in overweight subjects who develop impaired fasting glucose: a 3-year prospective study.

Circulating sex hormone-binding globulin (SHBG), corticosteroid-binding globulin (CBG), and total and calculated free cortisol were measured in 206 overweight subjects to investigate whether or not they were markers of insulin resistance. Measurements were carried out on two occasions 36 months apart and subjects were grouped according to fasting plasma glucose. Fifty-one subjects, with a normal basal fasting glucose (<5.6 mmol/l) developed impaired fasting glucose 3 years later (> or = 5.6 mmol/l). Analysis either in toto or based on gender showed a highly significant increase in fasting insulin and insulin resistance, a modest increase in body mass index (BMI), but importantly no change in plasma SHBG, CBG, or cortisol concentrations. Subjects (n=101) with a normal fasting glucose both at baseline (<5.6 mmol/l) and at 36 months showed no significant change in fasting insulin, insulin resistance, SHBG, CBG, cortisol, or BMI. Cross-sectional analysis of the study population showed that plasma SHBG correlated negatively with insulin resistance both in men and women. Overall SHBG at baseline was not predictive of changes in fasting glucose. In females, plasma CBG correlated negatively with BMI. The major finding is that overweight subjects who developed impaired fasting glucose showed no significant change in plasma SHBG, CBG or cortisol, and therefore these indices are probably not early markers of insulin resistance in overweight subjects.

Epstein-Barr virus shed in saliva is high in B-cell-tropic glycoprotein gp42.

Epstein-Barr virus is an orally transmitted human herpesvirus that infects epithelial cells and establishes latency in memory B lymphocytes. Movement of virus between the two cell types is facilitated by changes in amounts of an envelope glycoprotein, gp42, which are effected by interaction of gp42 with HLA class II in a B cell. Here we used the differential ability of virus to bind to CD21-positive B cells and CD21-negative epithelial cells, which is also influenced by levels of gp42, to determine that the majority of virus shed in saliva is derived from an HLA class II-negative cell.

Short-term statin treatment improves endothelial function and neurohormonal imbalance in normocholesterolaemic patients with non-ischaemic heart failure.

OBJECTIVES: To investigate the effect of short-term statin treatment on impaired endothelium-dependent vasodilatation and haemodynamic abnormalities typically occurring in chronic heart failure (CHF). METHODS: In a double-blind, crossover study endothelium-dependent vasodilatation was measured in conduit and resistance vessels of 23 patients with non-ischaemic CHF after 6 weeks of placebo and 40 mg atorvastatin. The haemodynamic impact was assessed by cardioendocrine hormones, echocardiography and clinical indicators of CHF. RESULTS: Cholesterol concentrations were population average (low density lipoprotein 3.56 (SEM 0.16) mmol/l, triglycerides 1.70 (0.20) mmol/l and high density lipoprotein 1.17 (0.07) mmol/l). In resistance vessels, the area under the curve ratio during acetylcholine infusion increased from 9.2 (1.9) with placebo to 12.2 (2.1) with statin (p < 0.01). This improvement was reversed during co-infusion with the nitric oxide antagonist N(G)-monomethyl-L-arginine. In conduit arteries, flow-mediated dilatation increased from 5.64 (SEM 0.88)% with placebo to 6.83 (0.97)% with statin (p < 0.05). Endothelium-independent vasodilatation did not change (p = 0.68 for conduit and p = 0.45 for resistance vessels). Endothelin 1 and atrial natriuretic peptide (ANP) decreased from 1.57 (0.08) and 51.3 (1.0) with placebo to 1.42 (0.09) pg/ml (p < 0.05) and 42.1 (7.5) pmol/l (p < 0.05), respectively, with statin. CONCLUSIONS: In patients with non-ischaemic CHF and population-average cholesterol concentrations, short-term statin treatment improves endothelial function in conduit and resistance vessels and lowers plasma endothelin 1 and ANP concentrations.

Genetic screening of patients with familial hypercholesterolaemia (FH): a New Zealand perspective.

Using denaturing high performance liquid chromatography (DHPLC) to screen the LDL receptor gene of people with familial hypercholesterolaemia (FH) in Christchurch, New Zealand, we have identified mutations in 65 patients (44 different mutations, of which 15 are novel). We also test family members of probands for the mutation identified in their relative, allowing diagnosis of affected children and those without classical FH symptoms. This screening programme is helpful to clinicians and benefits FH patients and their families, and has provided us with a pool of LDL receptor variants on which to base research into this disease.

The postprandial state does not impair endothelial function in women with type 2 diabetes irrespective of glycaemic control.

AIMS/HYPOTHESIS: The postprandial state has been shown to be associated with endothelial dysfunction, a predictor of cardiovascular morbidity. In type 2 diabetes, postprandial metabolic excursions are prolonged and exaggerated, but less pronounced if glycaemic control is optimised. We investigated the impact of improved glycaemic control on endothelial function in the postprandial state. METHODS: We studied 19 postmenopausal women with type 2 diabetes and ten non-diabetic subjects. Participants with diabetes were re-studied 3 months after intensive glucose regulation. We measured forearm blood flow by strain gauge plethysmography during rest, during acetylcholine infusion and post ischaemia in the fasting state, and again 3 hours after a mixed meal (660 kcal, 55% fat). RESULTS: Endothelium-dependent vasodilation was impaired in the diabetic group (p<0.005) and improved following an HbA1c reduction of 0.96% (p<0.05 for high-dose acetylcholine infusion). Postprandial metabolic excursions were higher in the diabetic group (p<0.001, p<0.01 and p<0.05 for glucose, insulin and triglycerides respectively). Resting forearm blood flow increased in all groups after the meal (p<0.005). There was no difference in fasting and postprandial endothelium-dependent vasodilation before and after improved glucose regulation in either group. CONCLUSIONS/INTERPRETATION: The postprandial state does not impair endothelial function in non-diabetic women and does not make pre-existing endothelial dysfunction worse in women with type 2 diabetes, irrespective of glycaemic control.

Prospective audit of conversion from regular to lispro insulin during routine clinical care.

BACKGROUND: Randomized controlled trials show that lispro insulin has the potential to improve glycaemic control. Observational, practice-based studies provide information that is complementary to that obtained from randomized controlled trials and results of both types of studies are of relevance when advising patients of likely outcomes during routine clinical care. AIMS: This prospective audit aimed to determine whether conversion from regular (short-acting, soluble) preprandial insulin to lispro during routine clinical care improved glycated haemoglobin. METHODS: Eligible patients were those using regular insulin before main meals and a basal neutral protamine Hagedorn (NPH) insulin. Study group patients were those who chose to convert to lispro insulin. Patients who elected not to change their regimen were used as a comparison group. Follow up was for a minimum of 1 year. RESULTS: Glycated haemoglobin (HbA(1c)) and body mass index showed no change in either the study or comparison groups. Post-hoc analysis revealed that the patients most likely to improve their HbA(1c) on lispro were those with a higher baseline HbA(1c). Patients using lispro reported a decreased frequency of hypoglycaemia and improved convenience of use. CONCLUSIONS: Administration of lispro insulin was perceived by patients as convenient to use and was also associated with less hypoglycaemia when compared with the use of regular insulin. There was, however, no improvement in HbA(1c). This finding may be informative when advising patients during routine clinical care of the likely metabolic outcome of changing their insulin regimen.

Plasma sex hormone-binding globulin rather than corticosteroid-binding globulin is a marker of insulin resistance in obese adult males.

AIM: Plasma levels of corticosteroid-binding globulin (CBG) and sex hormone-binding globulin (SHBG) may be regulated by insulin. The aim of this study was to test the hypothesis that these steroid-binding proteins are markers of insulin resistance and obesity in adult patients with the metabolic syndrome. METHODS: Fasting blood samples were obtained from 108 male and 88 female overweight adult patients who had varying degrees of dyslipidaemia, adiposity and insulin resistance. We measured plasma levels of SHBG and CBG and investigated their correlation with insulin resistance [homeostasis model assessment (HOMA) % sensitivity] and anthropometric markers of adiposity. RESULTS: In male patients, plasma SHBG correlated positively with HOMA (% sensitivity) and negatively with anthropometric measurements, including body mass index, waist circumference (cm) and percentage body fat. There was no correlation with CBG and any other parameter in the male patients. The female patients were treated as two groups, those not using oral contraceptives or hormone replacement therapy (n = 67) and those taking steroid medications (n = 21). Female patients using steroid medications had significantly higher SHBG levels but neither group showed any correlation between SHBG, insulin resistance and adiposity. Correlation studies of CBG with other parameters in the female subgroups did not reach statistical significance. CONCLUSIONS: We conclude that plasma SHBG is another surrogate marker for insulin resistance in obese males but not in obese females. It also appears that plasma CBG is not a useful marker of insulin resistance in patients with the metabolic syndrome.

Plasma adiponectin in overweight, nondiabetic individuals with or without insulin resistance.

AIM: Adiponectin is a protein produced exclusively by adipocytes with putative insulin-sensitizing and anti-atherogenic properties. This cross-sectional study investigated the relationship between plasma adiponectin and a range of anthropometric, glycaemic, lipid and inflammatory parameters in overweight and obese subjects expressing characteristics of the metabolic syndrome. METHODS: Subjects were selected for the study from a clinical database, if they were non-diabetic, overweight [body mass index (BMI) > 25] and had features of the metabolic syndrome. The subjects were grouped according to BMI (25-30, 31-35 and >35 kg/m2) and then stratified for insulin resistance [homeostasis model assessment (HOMA) %S]. One hundred and ninety-seven patients (109 males and 88 females) were selected for the study by taking an equal number with the highest and lowest HOMA indices from each of the three BMI groups. Plasma adiponectin concentration was measured in duplicate by radioimmunoassay, and the relationship between these levels and the other parameters was investigated using correlation and multiple linear regression analyses. RESULTS: Plasma adiponectin concentration was higher in females than males (median 10.3 vs. 7.1 micro g/ml, p < 0.001) despite being matched for BMI. In both genders, adiponectin levels were inversely related to BMI, waist circumference, percentage body fat, insulin resistance and the fasting plasma concentration of leptin. A direct correlation in both sexes was found between adiponectin levels and high-density lipoprotein (HDL)-cholesterol, apolipoprotein A1 and age. Multiple linear regression analyses showed that the independent determinants of low plasma adiponectin concentrations were gender, age, BMI, insulin resistance and HDL-cholesterol. An association between reduced adiponectin and increased high-sensitivity plasma C-reactive protein concentration was observed only in female subjects and was independent of anthropometric variables. Our observation that adiponectin levels increase with age differs from the majority of other studies and may simply reflect the demographics of the population studied. CONCLUSIONS: This study shows that adiponectin is an important molecular link between obesity, insulin resistance and atherogenic lipoproteins. It is possible that plasma adiponectin concentration may be a convenient marker for identifying subjects with the metabolic syndrome who may progress to impaired glucose tolerance. Longitudinal studies are required in order to verify this clinical application of adiponectin.