GooD4Mum: A general practice-based quality improvement collaborative for diabetes prevention in women with previous gestational diabetes

AIMS

Gestational diabetes (GDM) and Type 2 diabetes pose tremendous health and economic burdens as worldwide incidence increases. Primary care-based systematic diabetes screening and prevention programs could be effective in women with previous GDM. GooD4Mum aimed to determine whether a Quality Improvement Collaborative (QIC) would improve postpartum diabetes screening and prevention planning in women with previous GDM in general practice.

METHODS

Fifteen general practices within Victoria (Australia) participated in a 12-month QIC, consisting of baseline and four quarterly audits, guideline-led workshops and Plan-Do-Study-Act feedback cycles after each audit. The primary outcome measures were the proportion of women on local GDM registers completing a diabetes screening test and a diabetes prevention planning consultation within the previous 15 months.

RESULTS

Diabetes screening increased with rates more than doubled from 26% to 61% and postpartum screening increased from 43%-60%. Diabetes prevention planning consultations did not show the same level of increase (0%-10%). The recording of body mass index improved overall (51%-69%) but the number of women with normal body mass index did not.

CONCLUSIONS

GooD4Mum supported increased diabetes screening and the monitoring of high risk women with previous GDM in general practice.

Can the Mediterranean diet lower HbA1c in type 2 diabetes? Results from a randomized cross-over study

BACKGROUND AND AIMS

To investigate the impact of a diet modeled on the traditional Cretan Mediterranean diet on metabolic control and vascular risk in type 2 diabetes.

METHODS AND RESULTS

Twenty-seven subjects (47-77 yrs) with type 2 diabetes were randomly assigned to consume either the intervention diet ad libitum or their usual diet for 12 weeks and then cross over to the alternate diet. Most of the meals and staple foods for the intervention diet were provided. Lipids, glycemic variables, blood pressure, homocysteine, C-reactive protein, plasma carotenoids and body composition (anthropometry and dual energy X-ray absorptiometry) were assessed at baseline, and at the end of both diet periods. Dietary adherence was monitored using plasma carotenoid and fatty acid (FA) analysis, complemented by diet diaries. Compared with usual diet, on the ad libitum Mediterranean intervention diet glycosylated haemoglobin fell from 7.1% (95% CI: 6.5-7.7) to 6.8% (95% CI: 6.3-7.3) (p=0.012) and diet quality improved significantly [plant:animal (g/day) food ratio increased from 1.3 (95% CI: 1.1-1.5) to 5.4 (95% CI: 4.3-6.6) (p<0.001)], plasma lycopene and lutein/zeaxanthin increased (36% and 25%, respectively), plasma saturated and trans FAs decreased, and monounsaturated FAs increased.

CONCLUSION

A traditional moderate-fat Mediterranean diet improves glycemic control and diet quality in men and women with well-controlled type 2 diabetes, without adverse effects on weight.

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.

Ability of traditional lipid ratios and apolipoprotein ratios to predict cardiovascular risk in people with type 2 diabetes

AIMS/HYPOTHESIS

The apolipoprotein B (ApoB):apolipoprotein A (ApoA)-I ratio may be a better indicator of cardiovascular disease (CVD) risk in people with type 2 diabetes than traditional lipid risk markers (LDL-cholesterol, HDL-cholesterol and triacylglycerol), but whether the ApoB:ApoA-I ratio should be used to indicate lipid-lowering therapy is still debated.

METHODS

The Fenofibrate Intervention and Event Lowering in Diabetes (FIELD) study randomised 9,795 patients with type 2 diabetes to fenofibrate (200 mg daily) or placebo and followed them up for a median of 5 years. We compared ApoB, ApoA-I, ApoAII and the ApoB:ApoA-I ratio with traditional lipid variables as predictors of CVD risk. We estimated the HR of the effect of 1 SD difference in baseline concentrations of lipids, apolipoproteins and respective ratios on the risk of CVD events and also used receiver operating characteristic curve analysis.

RESULTS

In the placebo group, the variables best predicting CVD events were non-HDL-cholesterol:HDL-cholesterol, total cholesterol:HDL-cholesterol (HR 1.21, p < 0.001 for both), ApoB:ApoA-I (HR 1.20, p < 0.001), LDL-cholesterol:HDL-cholesterol (HR 1.17, p < 0.001), HDL-cholesterol (HR 0.84, p < 0.001) and ApoA-I (HR 0.85, p < 0.001). In the fenofibrate group, the first four predictors were very similar (but ApoB:ApoA-I was fourth), followed by non-HDL-cholesterol and ApoB. Lipid ratios and ApoB:ApoA-I performed better than any single lipid or apolipoprotein in predicting CVD risk.

CONCLUSIONS/INTERPRETATION

In patients with type 2 diabetes in the FIELD study, traditional lipid ratios were as strong as the ApoB:ApoA-I ratio in predicting CVD risk. The data provide little evidence for replacement of traditional lipids and their ratios with measures of ApoB, ApoA-I and their ratio.

Zebrafish: An in vivo model for the study of neurological diseases

As the population ages, there is a growing need for effective therapies for the treatment of neurological diseases. A limited number of therapeutics are currently available to improve cognitive function and research is limited by the need for in vivo models. Zebrafish have recently become a focus of neurobehavioral studies since larvae display neuropathological and behavioral phenotypes that are quantifiable and relate to those seen in man. Due to the small size of Zebrafish larvae, assays can be undertaken in 96 well plates and as the larvae can live in as little as 200 mul of fluid, only a few milligrams of compound are needed for screening. Thus in vivo analysis of the effects of compounds can be undertaken at much earlier stages in the drug discovery process. This review will look at the utility of the zebrafish in the study of neurological diseases and its role in improving the throughput of candidate compounds in in vivo screens.

Australian Aboriginal people and Torres Strait Islanders have an atherogenic lipid profile that is characterised by low HDL-cholesterol level and small LDL particles

AIM

To characterise lipid profiles for Australian Aboriginal people and Torres Strait Islanders.

METHODS

Community-based, cross-sectional surveys in 1995-1997 including: 407 female and 322 male Australian Aboriginal people and 207 female and 186 male Torres Strait Islanders over 15 years old. A comparator of 78 female (44 with diabetes) and 148 male (73 with diabetes) non-indigenous participants recruited to clinical epidemiological studies was used. Lipids were determined by standard assays and LDL diameter by gradient gel electrophoresis.

RESULTS

Diabetes prevalence was 14.8% and 22.6% among Aboriginal people and Torres Strait Islanders, respectively. LDL size (mean [95% CI (confidence interval)]) was smaller (P<0.05) in non-diabetic Aboriginal (26.02 [25.96-26.07] nm) and Torres Strait Islander women (26.01 [25.92-26.09] nm) than in non-diabetic non-indigenous women (26.29 [26.13-26.44] nm). LDL size correlated (P<0.0005) inversely with triglyceride, WHR, and fasting insulin and positively with HDL-cholesterol. HDL-cholesterol (mean [95% CI] mmol/L) was lower (P<0.0005) in indigenous Australians than in non-indigenous subjects, independent of age, sex, diabetes, WHR, insulin, triglyceride, and LDL size: Aboriginal (non-diabetic women, 0.86 [0.84-0.88]; diabetic women, 0.76 [0.72-0.80]; non-diabetic men, 0.79 [0.76-0.81]; diabetic men, 0.76 [0.71-0.82]); Torres Strait Islander (non-diabetic women, 1.00 [0.95-1.04]; diabetic women, 0.89 [0.83-0.96]; non-diabetic men, 1.00 [0.95-1.04]; diabetic men, 0.87 [0.79-0.96]); non-indigenous (non-diabetic women, 1.49 [1.33-1.67]; diabetic women, 1.12 [1.03-1.21]; non-diabetic men, 1.18 [1.11-1.25]; diabetic men, 1.05 [0.98-1.12]).

CONCLUSIONS

Indigenous Australians have a dyslipidaemia which includes small LDL and very low HDL-cholesterol levels. The dyslipidaemia was equally severe in both genders. Strategies aimed at increasing HDL-cholesterol and LDL size may reduce high CVD risk for indigenous populations.

Increased serum pigment epithelium-derived factor is associated with microvascular complications, vascular stiffness and inflammation in Type 1 diabetes

AIMS

To determine in Type 1 diabetes patients if levels of pigment epithelium-derived factor (PEDF), an anti-angiogenic, anti-inflammatory and antioxidant factor, are increased in individuals with complications and positively related to vascular and renal dysfunction, body mass index, glycated haemoglobin, lipids, inflammation and oxidative stress.

METHODS

Serum PEDF levels were measured by ELISA in a cross-sectional study of 123 Type 1 diabetic patients (71 without and 52 with microvascular complications) and 31 non-diabetic control subjects. PEDF associations with complication status, pulse-wave analysis and biochemical results were explored.

RESULTS

PEDF levels [geometric mean (95% CI)] were increased in patients with complications 8.2 (7.0-9.6) microg/ml, vs. complication-free patients [5.3 (4.7-6.0) microg/ml, P < 0.001] and control subjects [5.3 (4.6-6.1) microg/ml, P < 0.001; anova between three groups, P < 0.001], but did not differ significantly between control subjects and complication-free patients (P > 0.05). In diabetes, PEDF levels correlated (all P < 0.001) with systolic blood pressure (r = 0.317), pulse pressure (r = 0.337), small artery elasticity (r = -0.269), glycated haemoglobin (r = 0.245), body mass index (r = 0.362), renal dysfunction [including serum creatinine (r = 0.491), cystatin C (r = 0.500)], triglycerides (r = 0.367), and inflammation [including log(e)C-reactive protein (CRP; r = 0.329), and soluble vascular cell adhesion molecule-1 (r = 0.363)]. Age, blood urea nitrogen, systolic blood pressure, pulse pressure and log(e)CRP correlated with PEDF levels in control subjects (all P < 0.04). PEDF levels were not significantly correlated with measures of oxidative stress: isoprostanes, oxidized low-density lipoprotein or paraoxonase-1 activity. On stepwise linear regression analysis (all subjects), independent determinants of PEDF levels were renal function, triglycerides, inflammation, small artery elasticity and age (r(2) = 0.427).

CONCLUSIONS

In Type 1 diabetes, serum PEDF levels are associated with microvascular complications, poor vascular health, hyperglycaemia, adiposity and inflammation.

Widespread vascular production of C-reactive protein (CRP) and a relationship between serum CRP, plaque CRP and intimal hypertrophy

OBJECTIVES

Evidence of local vascular production and a relationship between serum hsCRP levels and tissue expression of CRP in subjects with vascular disease would support a direct role for CRP in atherosclerosis.

METHODS AND RESULTS

Vascular tissue from subjects undergoing coronary artery bypass grafting surgery (CABGS) (n=28) and carotid endarterectomy (CEA) (n=25) were studied. Histological samples were assessed for intima-media ratio (IMR) and CRP by immunohistochemistry. CRP mRNA was quantified by real-time polymerase chain reaction. CRP mRNA was seen in all plaques, non-atherosclerotic artery and atrium but no difference in mRNA expression was seen between plaque and non-atherosclerotic tissue. Serum hsCRP correlated with IMR (r=0.64, p=0.001) in non-atherosclerotic arteries and with plaque CRP staining (r=0.57, p=0.009) independent of age, BMI, lipids, diabetes and blood pressure. In a separate patient series, serum hsCRP was measured in aortic and coronary sinus blood from subjects undergoing CABGS or angiography (n=54). There was a coronary circulation hsCRP gradient ([mean+/-S.E.M.] aortic CRP 4.3mg/l+/-0.8 versus coronary sinus 5.8+/-1.2mg/l, p<0.05).

CONCLUSIONS

Widespread vascular CRP mRNA expression, a correlation between serum hsCRP, intimal hypertrophy and plaque CRP, and a coronary hsCRP gradient suggest vascular secretion may contribute to serum CRP levels.

Differential association of C-reactive protein with adiposity in men and women in an Aboriginal community in northeast Arnhem Land of Australia

OBJECTIVE

To examine the relationship between C-reactive protein (CRP), adiposity and other metabolic abnormalities in an Aboriginal community in Northern Australia.

DESIGN

Cross-sectional analysis of data obtained between 2001 and 2003 from 379 Aboriginal people residing in a geographically isolated community.

RESULTS

Mean (95% CI) CRP in women and men was 4.06 cholesterol (3.53, 4.66) mg/l and 3.42 (2.94, 3.97) mg/l, respectively (P=NS). The prevalence of the metabolic syndrome (US National Cholesterol Education [corrected] Program (NCEP) definition) was significantly higher for women than men (41 vs 18%, chi (2)=20.94, P<0.001). C-reactive protein correlated strongly with adiposity in women (waist circumference, waist to hip ratio and body mass index; r>/=0.514, P<0.01) but much less strongly in men (r</=0.221, P<0.05). In a multivariate stepwise linear regression model, waist circumference was the strongest independent predictor explaining 35% of CRP concentration variance in women, but only 5.4% in men (WHR). Incremental increases in CRP concentration across four BMI categories were significant in women (P (linear trend)<0.001) but not in men.

CONCLUSIONS

High CRP levels in the surveyed population are consistent with the high prevalence of vascular disease morbidity and mortality in Aboriginal Australians. The relationship of CRP with increasing body fat was strong and consistent in women but not in men. Prospective studies are needed to elucidate the role of CRP (if any) as a predictive marker for cardiovascular events in this high-risk population.

Traditional risk factor assessment does not capture the extent of cardiovascular risk in systemic lupus erythematosus

BACKGROUND

Systemic lupus erythematosus (SLE) is associated with accelerated atherosclerosis. However, the degree of endothelial dysfunction and its relationship to traditional and novel cardiovascular risk factors have not been examined in SLE.

METHODS

In a case-control design, 35 patients with clinically stable SLE and 35 control subjects matched for age, sex, body mass index and smoking status were studied. Arterial elasticity, lipid profile, homocysteine, measures of inflammation and oxidative stress were determined.

RESULTS

Among traditional vascular risk factors, there was a nonsignificant trend towards lower blood pressure in the control subjects, whereas low-density lipoprotein (LDL) cholesterol levels were significantly lower in the SLE group (2.5 vs 3.3 mmol/L, P < 0.001). Patients with SLE had significantly lower small artery elasticity (SAE; 4.9 vs 7.0 ml/mmHg x 100, P < 0.001) and higher plasma homocysteine (11.4 vs 8.3 mmol/L, P = 0.002) than control subjects. Levels of serum sVCAM-1 (614 vs 494 ng/mL, P = 0.002), oxidized LDL (144 vs 97, P < 0.001) and CD40 ligand (4385 vs 1373 pg/ml, P = 0.001) were significantly higher in SLE. Oxidized LDL levels, older age at SLE diagnosis and higher disease damage scores correlated inversely with SAE but not traditional risk factors.

CONCLUSION

Impaired endothelial function as shown by decreased SAE, and an adverse profile of novel proatherogenic and prothrombotic vascular disease risk factors were prevalent in clinically quiescent SLE. These findings show the vulnerability of patients with SLE for atherosclerosis, and emphasize that assessments based on traditional risk factors alone may be inadequate.

The metabolic syndrome and changing relationship between blood pressure and insulin with age, as observed in Aboriginal and Torres Strait Islander peoples

AIMS

To determine the prevalence of the metabolic syndrome (MS) among Aboriginal and Torres Strait Islander peoples. A further objective was to investigate the relationships between fasting insulin and blood pressure (BP) within these groups with increasing age.

METHODS

A cross-sectional population-based study included 369 Torres Strait Islanders (residing in Torres Strait and Far North Queensland), and 675 Aborigines from central Australia. Data necessary for classification of MS was collected, including fasting and 2-h glucose and insulin, urinary albumin and creatinine, anthropometric measurements, BP, serum lipids.

RESULTS

The ATPIII criteria classified 43% of Torres Strait Islanders and 44% of Aborigines with MS, whereas 32 and 28%, respectively, had the MS according to WHO criteria. Agreement between the two criteria was only modest (kappa coefficient from 0.28 to 0.57). Factor analyses indicated no cluster including both insulin and BP in either population. Significant correlations (P < 0.05) [adjusted for gender, body mass index (BMI) and waist circumference] were observed between BP and fasting insulin: a positive correlation for Torres Strait Islanders aged 15-29 years, and an inverse correlation for Aborigines aged 40 years and older.

CONCLUSION

Torres Strait Islanders and Aborigines had very high prevalences of the MS. Specific population characteristics (high prevalences of central obesity, dyslipidaemia, renal disease) may make the WHO definition preferable to the ATPIII definition in these population groups. The poor agreement between criteria suggests a more precise definition of the metabolic syndrome that is applicable across populations is required. This study showed an inverse relationship with age for the correlation of BP and fasting insulin.

Plasma low-molecular weight fluorescence in type 1 diabetes mellitus

Characteristic tissue fluorescence is associated with advanced glycation end product (AGE) accumulation in experimental diabetes models, but its utility in patients with type 1 diabetes remains to be established. We studied 148 patients with type 1 diabetes and 77 healthy age-matched control subjects. Low-molecular weight (LMW) fluorophore levels were estimated in plasma samples obtained after an overnight fast. Intra- and interassay coefficients of variation were 4.7% and 6.4%, respectively. LMW fluorophore levels were significantly higher in patients with diabetes than in control subjects (6.3 +/- 0.6 AU/mL vs. 4.1 +/- 0.3; P = 0.007). However, all of this difference came from patients with microvascular complications (n = 67, 7.5 +/- 1.3). There was no significant difference in LMW fluorescence between complication-free patients (4.4 +/- 0.2) and control subjects (P > 0.05). On multivariate analysis, LMW fluorophores correlated with measures of renal function (P < 0.05) but not with diabetes per se. In addition, there was no correlation between LMW fluorophores and the markers of oxidative stress or systemic inflammation. Longitudinal and interventional studies are required to determine whether the association between LMW fluorophores and nephropathy is cause or effect.

Oxidized LDL and small LDL particle size are independently predictive of a selective defect in microcirculatory endothelial function in type 2 diabetes

AIM

To explore the associations of LDL (low-density lipoprotein) particle size and oxidized LDL with endothelium-dependent function of the forearm microcirculation in diabetes.

METHODS

Endothelium-dependent function was examined in 43 middle-aged men and women with type 2 diabetes and 10 age-matched controls. All received aspirin to inhibit endothelial cyclo-oxygenase. Forearm blood flow (FBF) was measured using venous occlusion plethysmography with separate administration of acetylcholine (ACh) and bradykinin (BK) into the brachial artery. Endothelium-independent function was assessed using sodium nitroprusside (SNP). N(G)-monomethyl-L-arginine (L-NMMA) was co-infused with ACh (ACh + L-NMMA) and BK (BK + L-NMMA) to assess non-NO-mediated contributions to endothelium-dependent function.

RESULTS

Subjects with diabetes had impaired endothelium-dependent and endothelium-independent function compared with controls (p < 0.01 for ACh, BK and SNP). In multivariate regression analysis, LDL size (r = 0.41 and p = 0.007), oxidized LDL (r = -0.41 and p = 0.007) and duration of diabetes (r = -0.37 and p = 0.02) predicted FBF response to ACh independently of age, gender and systolic blood pressure. There were no associations between LDL size, oxidized LDL, duration of diabetes and FBF response to BK, SNP, ACh + L-NMMA or BK + L-NMMA.

CONCLUSION

In type 2 diabetes, small dense LDL particles, duration of diabetes and oxidized LDL may independently contribute to endothelial dysfunction of the microcirculation. These disturbances may occur via a selective defect, because ACh and BK activate endothelial NO synthase via different G-protein signal transduction pathways.

Expression of GLUT12 in the fetal membranes of the human placenta

The aim of this study was to characterize the expression of the novel glucose transporter GLUT12 in the fetal membranes of the human placenta. RT-PCR and Western blotting of extracts of amnion and choriodecidua from four normal term placentas identified GLUT12 mRNA and protein expression. In all four samples the signals for GLUT12 were markedly stronger in the choriodecidua than in the amnion, whereas the signals for GLUT1, a glucose transporter know to be expressed in fetal membranes, were similar for the two tissues. In further studies, paraffin sections of fetal membranes were analyzed by immunohistochemistry with GLUT12 and GLUT1-specific polyclonal antibodies. GLUT12 immunoreactivity was localized predominantly to the trophoblast cells in the chorion and to a lesser extent to decidual cells and to epithelial and fibroblast cells of the amnion. GLUT1 was localized to chorionic trophoblast cells and amniotic epithelial and fibroblast cells. GLUT12 expression was predominantly cytoplasmic, whereas GLUT1 was associated with the membrane of the cells. These results show that GLUT12 is expressed in cells of human fetal membranes and suggest that GLUT12 may play a role in the facilitation of glucose transport into these cells.

Lipoproteins and diabetic microvascular complications

Risk factors for the microvascular complications (nephropathy and retinopathy) of Type 1 and Type 2 diabetes mellitus and the associated accelerated atherosclerosis include: age, diabetes duration, genetic factors, hyperglycaemia, hypertension, smoking, inflammation, glycation and oxidative stress and dyslipoproteinaemia. Hypertriglyceridaemia, low HDL and small dense LDL are common features of Type 2 diabetes and Type 1 diabetes with poor glycaemic control or renal complications. With the expansion of knowledge and of clinical and research laboratory tools, a broader definition of 'lipid' abnormalities in diabetes is appropriate. Dyslipoproteinaemia encompasses alterations in lipid levels, lipoprotein subclass distribution, composition (including modifications such as non-enzymatic glycation and oxidative damage), lipoprotein-related enzymes, and receptor interactions and subsequent cell signaling. Alterations occur in all lipoprotein classes; chylomicrons, VLDL, LDL, HDL, and Lp(a). There is also emerging evidence implicating lipoprotein related genotypes in the development of diabetic nephropathy and retinopathy. Lipoprotein related mechanisms associated with damage to the cardiovascular system may also be relevant to damage to the renal and ocular microvasculature. Adverse tissue effects are mediated by both alterations in lipoprotein function and adverse cellular responses. Recognition and treatment of lipoprotein-related risk factors, supported by an increasing array of assays and therapeutic agents, may facilitate early recognition and treatment of high complication risk diabetic patients. Further clinical and basic research, including intervention trials, is warranted to guide clinical practice. Optimal lipoprotein management, as part of a multi-faceted approach to diabetes care, may reduce the excessive personal and economic burden of microvascular complications and the related accelerated atherosclerosis.

GLUT12 expression in human placenta in first trimester and term

The aim of this study was to characterize the expression of a novel glucose transporter protein GLUT12 in human placenta. GLUT12 mRNA expression was identified by RT-PCR in extracts from five normal term placentae and in extracts from cultured cells of the JAR, JEG-3 and HTR-8Svneo cell lines. In further studies, paraffin sections of first trimester tissue from chorionic villus sampling and term tissue obtained after delivery were analysed by immunohistology with a GLUT12 specific polyclonal antibody. GLUT12 immunoreactivity was expressed predominantly in the syncytiotrophoblast and in extra-villous trophoblast cells in first trimester tissues at 10, 11 and 12 weeks' gestation. In term tissue, however, GLUT12 staining was not detected in syncytiotrophoblast and was found predominantly in villous vascular smooth muscle cells and villous stromal cells. These results suggest that there is a dynamic spatial and temporal expression pattern for the novel glucose transporter GLUT12 in human placenta.

Novel agents for managing dyslipidaemia

An elevated low-density lipoprotein (LDL) cholesterol level is a strong predictor of coronary heart disease (CHD) risk. Over the past seven years, equally strong evidence has accumulated that lowering LDL cholesterol with HMG-CoA reductase inhibitors or statins reduces CHD risk and there is now widespread use of these agents for the primary and secondary prevention of CHD. Treatment issues remain regarding the appropriate degree of LDL cholesterol reduction and whether, in people with very high levels, it would be preferable to achieve the LDL cholesterol goal with a powerful statin alone or combined with an agent that lowers LDL cholesterol by a different mechanism. The main focus in the development of novel agents is the patient with low high-density lipoprotein (HDL) cholesterol, usually associated with hypertriglyceridaemia. Already prevalent as a risk factor for CHD, this abnormality has been linked with insulin resistance, which is likely to increase greatly over the next decade, along with increasing obesity and diabetes. Agents that have potent HDL cholesterol raising capacity include cholesteryl ester transfer protein (CETP) inhibitors, retinoid X receptor (RXR) selective agonists, specific peroxisome proliferator-activated receptor (PPAR) agonists and oestrogen-like compounds. Another area of development involves agents that will lower both cholesterol and triglyceride levels, such as partial inhibitors of microsomal triglyceride transfer protein (MTP) and perhaps squalene synthase inhibitors and agonists of AMP kinase. Future emphasis will be on correcting all lipid abnormalities for the prevention of CHD, not just lowering LDL cholesterol.

Effects of monounsaturated enriched sunflower oil on CHD risk factors including LDL size and copper-induced LDL oxidation

OBJECTIVE

To compare the effects of a diet high in monounsaturated enriched sunflower oil and a low fat diet on CHD risk factors including in vitro Cu-induced LDL oxidation and LDL size, lipids, lipoproteins, glucose and insulin.

DESIGN

A randomized crossover dietary intervention.

SETTING

Free living individuals.

SUBJECTS

Fourteen healthy males 35 to 55 years of age and 14 healthy postmenopausal women 50 to 60 years of age completed the dietary intervention. Two subjects did not complete the study, and their data were not included.

INTERVENTIONS

A low fat, high carbohydrate diet (22% to 25% of energy from total fat, 7% to 8% of energy from monounsaturated fat and 55% to 60% of energy from carbohydrate) was compared to a monounsatutated enriched sunflower oil (MO) diet (40% to 42% of energy from fat, with 26% to 28% from monounsaturated fat and 40% to 45% of energy from carbohydrate) in an isocaloric substitution. Each dietary period was one month.

RESULTS

Total cholesterol, LDL cholesterol, triglycerides and glucose were not significantly different between the two diets. HDL cholesterol, HDL3 cholesterol and insulin were significantly higher on the MO diet, mean 7%, 7% and 17% higher respectively. Copper-induced LDL oxidation lag phase was significantly longer (mean 18%) after the MO diet compared to the low fat, high carbohydrate diet. LDL particle size was not significantly different.

CONCLUSIONS

The significant increase in LDL oxidation lag phase and the significantly higher HDL cholesterol on the MO diet would be expected to be associated with a decrease in CHD risk.

Vascular function of the peripheral circulation in patients with nephrosis

BACKGROUND

Nephrotic syndrome is associated with abnormal lipoprotein metabolism and increased risk of coronary heart disease. Endothelial dysfunction, an early phase of atherogenesis that manifests as impaired flow-mediated dilation (FMD) of the peripheral circulation, may link these associations.

METHODS

We examined endothelial function of the brachial artery and forearm resistance arteries in 15 patients with nephrosis (NP), 15 patients with primary hyperlipidemia (HL) alone, and 15 normolipidemic, nonproteinuric subjects (NC) matched for age, sex, and weight. The NP and HL groups had similar serum cholesterol and triglyceride concentrations. Post-ischemic FMD (endothelium-dependent) and glyceryl trinitrate-mediated dilation (GTNMD; endothelium-independent) of the brachial artery were studied using ultrasonography and computerized edge detection software. Postischemic forearm blood flow was also measured using plethysmography.

RESULTS

Postischemic FMD of the brachial artery was significantly lower in the NP and HL groups compared with NC group (mean +/- SE): NP 4.91 +/- 0.8%, HL 4.53 +/- 0.6%, NC 8.45 +/- 0.5% (P < 0.001). There were no significant differences among the groups in baseline diameter and GTNMD of the brachial artery, nor in maximal forearm blood flow and flow debt repayment of the forearm microcirculation. Significant differences in FMD among the groups were principally related to differences in serum low-density lipoprotein cholesterol.

CONCLUSIONS

Patients with NP have abnormal endothelium-dependent but preserved endothelium-independent dilation of the brachial artery following an ischemic stimulus. Postischemic forearm microcirculatory function is unimpaired. Dyslipoproteinemia is probably the principal cause of endothelial dysfunction of conduit arteries in patients with NP and the basis for their increased risk of cardiovascular disease.

Insulin resistance as a major determinant of increased coronary heart disease risk in postmenopausal women with Type 2 diabetes mellitus

AIM

To investigate the risk factors associated with clinically defined coronary heart disease (CHD) in women with Type 2 diabetes mellitus (DM).

METHODS

CHD status was assessed via standard history and resting electrocardiogram in 41 postmenopausal diabetic and 41 age- and body mass index-matched normoglycaemic women recruited from a community-based cohort. The following parameters were assessed: body composition by dual energy X-ray absorptiometry, blood pressure, metabolic and lipoprotein profile and haemostatic factors.

RESULTS

Diabetic women with CHD (n = 14) had greater insulin resistance, calculated by homeostasis model assessment (10.2 (7.0-14.8) vs. 6.5 (5.5-7.7), P = 0.010), and higher plasminogen activator inhibitor-1 (PAI-1) levels (45 (29-69) vs. 24 (19-32) ng/ml, P = 0.013), than those without CHD. They also had higher triglycerides (2.9 (2.2-3.8) vs. 2.1 (1.8-2.4) mmol/l, P = 0.016) and a trend towards reduced low-density lipoprotein particle size (25.5 +/- 0.6 vs. 25.8 +/- 0.5 nm, P = 0.097). In a logistic regression model, insulin resistance was a significant independent predictor of CHD status (odds ratio = 1.33, 95% confidence interval = 1.06-1.68, P = 0.015). In contrast, in normoglycaemic women the major risk factors for CHD were elevated cholesterol, apolipoprotein(a), apolipoprotein B and systolic blood pressure (P = 0.018, P = 0.016, P = 0.006 and P = 0.049, respectively).

CONCLUSIONS

Increased insulin resistance in association with elevated PAI-1 and dyslipidaemia appears to underpin the increased risk of CHD in women with Type 2 DM. Therapeutic approaches that increase insulin sensitivity may serve to reduce CHD risk in this vulnerable group. Diabet. Med. 18, 476-482 (2001)

Albuminuria in Australian Aboriginal people: prevalence and associations with components of the metabolic syndrome

AIMS/HYPOTHESIS

To examine the prevalence and associations with the metabolic syndrome of albuminuria among Australian Aboriginal people.

METHODS

Early-morning urine specimens were collected as part of community-based risk factor surveys assessing the prevalence of diabetes and cardiovascular disease in eight remote communities, with a sample size of 1,075 people. Microalbuminuria was defined as urinary albumin : creatinine ratio 3.4-33.9 mg/mmol, macroalbuminuria as albumin: creatinine ratio equal to or greater than 34 mg/mmol.

RESULTS

There were high prevalences of microalbuminuria (men 22.2 %, women 26.9 %) and of macroalbuminuria (men 10.4%, women 13.5%). There were highly statistically significant linear associations of microalbuminuria and macroalbuminuria with increasing number of coexisting components of the metabolic syndrome (hypertension, glucose intolerance, dyslipidaemia, insulin resistance, abdominal obesity): among people with zero, one, two and three to five of these conditions, respectively, prevalence of microalbuminuria was 16%, 20%, 36% and 32% (p < 0.001); prevalence of macroalbuminuria was 2%, 6%, 12% and 32% (p < 0.001). There were independent associations of microalbuminuria with hypertension (odds ratio, 95% confidence interval = 2.36, 1.63-3.42) and diabetes (2.10, 1.28-3.45): macroalbuminuria was independently associated with hypertension (6.39, 3.93-10.4), diabetes (3.49, 1.93-6.28) and abdominal obesity (4.56, 2.40-8.64) and had a weaker association with insulin resistance (1.99, 1.12-3.54). Dyslipidaemia and impaired glucose tolerance were neither independently associated with microalbuminuria or macroalbuminuria, nor was insulin resistance or abdominal obesity independently associated with microalbuminuria.

CONCLUSION/INTERPRETATION

There was a strong clustering of albuminuria with components of the metabolic syndrome. Diabetes, hypertension and abdominal obesity are major contributors to high rates of albuminuria among Australian Aboriginal people.

Diabetic dyslipidaemia: current treatment recommendations

Insulin deficiency and hyperglycaemia in type 1 (insulin-dependent) diabetes mellitus produce lipid abnormalities, which can be corrected by appropriate insulin therapy. Diabetic nephropathy, which is the main risk factor for coronary heart disease (CHD) in type 1 diabetes, causes pro-atherosclerotic changes in lipid metabolism. Detection and treatment of elevated cholesterol levels is likely to be of benefit in these patients. Type 2 (noninsulin-dependent) diabetes mellitus is associated with abnormal lipid metabolism, even when glycaemic control is good and nephropathy absent. Elevated triglyceride levels, reduced high density lipoprotein (HDL) cholesterol and a preponderance of small, dense low density lipoprotein (LDL) particles are the key abnormalities that constitute diabetic dyslipidaemia. The prevalence of hypercholesterolaemia is the same as for the nondiabetic population, but the relative risk of CHD is greatly increased at every level of cholesterol. Based on effectiveness, tolerability and clinical trial results, treatment with HMG-CoA reductase inhibitors to lower LDL cholesterol is recommended as primary therapy. These agents are also moderately effective at reducing triglyceride and increasing HDL cholesterol levels. If hypertriglyceridaemia predominates, treatment with fibric acid derivatives is appropriate, although there is currently only limited clinical trial evidence that the risk of CHD will be reduced. In type 1 diabetes, but particularly in type 2 diabetes, lipid disorders are likely to contribute significantly to the increased risk of macrovascular complications. especially CHD. Management of the disordered lipid metabolism should be given a high priority in the clinical care of all patients with diabetes.

Purified eicosapentaenoic and docosahexaenoic acids have differential effects on serum lipids and lipoproteins, LDL particle size, glucose, and insulin in mildly hyperlipidemic men

BACKGROUND

Regular consumption of n-3 fatty acids of marine origin can improve serum lipids and reduce cardiovascular risk.

OBJECTIVE

This study aimed to determine whether eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids have differential effects on serum lipids and lipoproteins, glucose, and insulin in humans.

DESIGN

In a double-blind, placebo-controlled trial of parallel design, 59 overweight, nonsmoking, mildly hyperlipidemic men were randomly assigned to receive 4 g purified EPA, DHA, or olive oil (placebo) daily while continuing their usual diets for 6 wk.

RESULTS

Fifty-six men aged 48.8 +/- 1.1 y completed the study. Relative to those in the olive oil group, triacylglycerols fell by 0.45 +/- 0.15 mmol/L ( approximately 20%; P = 0.003) in the DHA group and by 0.37 +/- 0.14 mmol/L ( approximately 18%; P = 0.012) in the EPA group. Neither EPA nor DHA had any effect on total cholesterol. LDL, HDL, and HDL(2) cholesterol were not affected significantly by EPA, but HDL(3) cholesterol decreased significantly (6.7%; P = 0.032). Although HDL cholesterol was not significantly increased by DHA (3. 1%), HDL(2) cholesterol increased by approximately 29% (P = 0.004). DHA increased LDL cholesterol by 8% (P = 0.019). Adjusted LDL particle size increased by 0.25 +/- 0.08 nm (P = 0.002) with DHA but not with EPA. EPA supplementation increased plasma and platelet phospholipid EPA but reduced DHA. DHA supplementation increased DHA and EPA in plasma and platelet phospholipids. Both EPA and DHA increased fasting insulin significantly. EPA, but not DHA, tended to increase fasting glucose, but not significantly so.

CONCLUSIONS

EPA and DHA had differential effects on lipids, fatty acids, and glucose metabolism in overweight men with mild hyperlipidemia.

The effect of 24 months recombinant human growth hormone (rh-GH) on LDL cholesterol, triglyceride-rich lipoproteins and apo [a] in hypopituitary adults previously treated with conventional replacement therapy

Hypopituitary adults receiving conventional hormone replacement therapy are reported to have increased cardiovascular mortality. Previous studies indicate that these patients have several abnormalities in lipoprotein metabolism, including reduced low density lipoprotein (LDL) uptake and impaired metabolism of triglyceride-rich lipoproteins. The effects of 24 months of 0.21 IU/kg per week recombinant growth hormone (rh-GH) on the lipoprotein profiles of 22 GH-deficient adults were studied. Samples were collected after a 12-h fast at baseline and 24 months. Total cholesterol, triglyceride, high-density lipoprotein (HDL) cholesterol, LDL cholesterol, apolipoprotein (apo) A, apo B and apo [a] were determined by routine laboratory methods. LDL particle size was determined by non-denaturing gradient gel electrophoresis. Visceral adiposity was determined by dual energy X-ray absorptiometry (DEXA). Insulin sensitivity was measured in a subset of 17 subjects using a two-stage hyperinsulinaemic-euglycaemic clamp. Significant reductions were observed in total cholesterol (5.3 +/- 0. 17 vs 4.9 +/- 0.23 mmol/l;P<0.05) and LDL cholesterol (3.4 +/- 0.17 vs 2.9 +/- 0.17 mmol/l; P<0.001) at 24 months when compared to baseline. No significant changes were observed in triglyceride level, HDL cholesterol level, apo B, apo A and LDL size. A significant increase in apo [a] [160 (96-416) vs 204 (127-534) U/l;P<0.05] was observed which appeared to be dose-dependent. Visceral adiposity was reduced significantly. Insulin sensitivity did not alter significantly. Replacement for 24 months with rh-GH has a differential effect on the lipid profile with a decrease in LDL, but little effect upon the metabolism of triglyceride-rich lipoproteins, manifested by unchanged triglyceride, HDL cholesterol levels and LDL size, despite the reduction in visceral adiposity. Conversely, apo [a], an independent risk factor for cardiovascular disease was increased. The ultimate effect of GH therapy upon cardiovascular mortality remains to be determined and may be dose-related.

Rapid resetting of the mammalian circadian clock

The suprachiasmatic nuclei (SCN) contain the principal circadian clock governing overt daily rhythms of physiology and behavior. The endogenous circadian cycle is entrained to the light/dark via direct glutamatergic retinal afferents to the SCN. To understand the molecular basis of entrainment, it is first necessary to define how rapidly the clock is reset by a light pulse. We used a two-pulse paradigm, in combination with cellular and behavioral analyses of SCN function, to explore the speed of resetting of the circadian oscillator in Syrian hamster and mouse. Analysis of c-fos induction and cAMP response element-binding protein phosphorylation in the retinorecipient SCN demonstrated that the SCN are able to resolve and respond to light pulses presented 1 or 2 hr apart. Analysis of the phase shifts of the circadian wheel-running activity rhythm of hamsters presented with single or double pulses demonstrated that resetting of the oscillator occurred within 2 hr. This was the case for both delaying and advancing phase shifts. Examination of delaying shifts in the mouse showed resetting within 2 hr and in addition showed that resetting is not completed within 1 hr of a light pulse. These results establish the temporal window within which to define the primary molecular mechanisms of circadian resetting in the mammal.

Glutamatergic induction of CREB phosphorylation and Fos expression in primary cultures of the suprachiasmatic hypothalamus in vitro is mediated by co-ordinate activity of NMDA and non-NMDA receptors

Exposure of Syrian hamsters to light 1 h after lights-off rapidly (10 min) induced nuclear immunoreactivity (-ir) to the phospho-Ser133 form of the Ca2+/cAMP response element (CRE) binding protein (pCREB) in the retinorecipient zone of the suprachiasmatic nuclei (SCN). Light also induced nuclear Fos-ir in the same region of the SCN after 1 h. The glutamatergic N-methyl-D-aspartate (NMDA) receptor blocker MK801 attenuated the photic induction of both factors. To investigate glutamatergic regulation of pCREB and Fos further, tissue blocks and primary cultures of neonatal hamster SCN were examined by Western blotting and immunocytochemistry in vitro. On Western blots of SCN tissue, the pCREB-ir signal at 45 kDa was enhanced by glutamate or a mixture of glutamatergic agonists (NMDA, amino-methyl proprionic acid (AMPA), and Kainate (KA)), whereas total CREB did not change. Glutamate or the mixture of agonists also induced a 56 kDa band identified as Fos protein in SCN tissue. In dissociated cultures of SCN, glutamate caused a rapid (15 min) induction of nuclear pCREB-ir and Fos-ir (after 60 min) exclusively in neurones, both GABA-ir and others. Treatment with NMDA alone had no effect on pCREB-ir. AMPA alone caused a slight increase in pCREB-ir. However, kainate alone or in combination with NMDA and AMPA induced nuclear pCREB-ir equal to that induced by glutamate. The effects of glutamate on pCREB-ir and Fos-ir were blocked by antagonists of both NMDA (MK801) and AMPA/KA (NBQX) receptors. In the absence of extracellular Mg2+, MK801 blocked glutamatergic induction of Fos-ir. However, the AMPA/KA receptor antagonist was no longer effective at blocking glutamatergic induction of either Fos-ir or pCREB-ir, consistent with the model that glutamate regulates gene expression in the SCN by a co-ordinate action through both NMDA and AMPA/KA receptors. Glutamatergic induction of nuclear pCREB-ir in GABA-ir neurones was blocked by KN-62 an inhibitor of Ca2+/Calmodulin (CaM)-dependent kinases, implicating Ca2+-dependent signalling pathways in the glutamatergic regulation of gene expression in the SCN.

Gemfibrozil treatment increases low-density lipoprotein particle size in Type 2 diabetes mellitus but does not alter in vitro oxidizability

The aim of this study was to determine the effect of the lipid modifying agent gemfibrozil on lipid and coagulation risk factors in patients with Type 2 diabetes mellitus (Type 2 DM). Twenty-six subjects with Type 2 DM and dyslipidaemia were treated for 24 weeks with either gemfibrozil 600 mg orally twice daily or placebo in a double-blind randomized trial. Lipid profiles, fibrinogen, Factor VII, and plasminogen activator inhibitor-1 (PAI-1) were measured by routine laboratory methods. Low density lipoprotein (LDL) size was determined by gradient gel electrophoresis and the resistance of LDL to copper-induced oxidation was assessed by measuring absorbance at 234 nm. Gemfibrozil significantly reduced total cholesterol (-0.9 (-0.48, -1.32) mmol l(-1); p < 0.05) and triglycerides (-2.7 (-1.55, -1.35) mmol l(-1); p < 0.001) vs placebo. The fall in triglyceride was reflected by a fall in VLDL cholesterol levels in the gemfibrozil treated group vs placebo (-1.31 mmol l(-1); p < 0.001). LDL-cholesterol level did not change but LDL particle size increased by 0.5 nm (0.01, 0.93); P < 0.02. The increase in particle size was inversely correlated with the change of triglyceride level (r = -0.79, p < 0.0001) but did not result in any reduction of susceptibility to copper-induced oxidation. There were no significant changes in the coagulation parameters studied. Because of its ability to correct the lipid abnormalities associated with Type 2 DM particularly hypertriglyceridaemia, gemfibrozil provides a useful therapeutic option in the management of diabetic dyslipidaemia but it does not alter in vitro oxidizability of LDL.

A comparison of LDL size determination using gradient gel electrophoresis and light-scattering methods

This study compared gradient gel electrophoresis (GGE) and light-scattering (LS) methods of determining low density lipoprotein (LDL) particle size. LDL was isolated from 27 fasting subjects. Peak particle size was determined by GGE on 3-13% gradient gels (Gradipore, Sydney, Australia) and by LS using a Zetasizer 3000 (Malvern Instruments, Malvern, UK). Repeated measurements on a single specimen indicated a coefficient of variation (CV) of 0.3%. A correlation was noted (P < 0.0001; r = 0.78) when comparing LDL particle size determined by LS methodology and GGE. Particle diameter results obtained by LS were smaller than those obtained by GGE (23.1 +/- 0.1 vs. 26.1 +/- 0.1 nm; P < 0.0001). LDL particle size determined by LS methodology correlated inversely with the log of triglyceride level (P < 0.0001; r = -0.77) and positively with high density lipoprotein (HDL) cholesterol level (P < 0.002; r = 0.57).

Insulin receptor expression in primary and cultured osteoclast-like cells

Skeletal growth is the net product of coordinated bone formation and resorption. Insulin is known to stimulate bone formation by actions on osteoblasts. It is not known whether insulin receptors are present on osteoclasts, or whether insulin regulates osteoclastic function. We present here immunocytochemical evidence of insulin receptor expression by mature mono- and multinucleated murine osteoclast-like cells generated in vitro, and in primary neonatal rat and mouse osteoclasts. Radiolabeled studies indicated that progressive enrichment of osteoclast-like cells in coculture was associated with increased insulin binding. When osteoclast-like cells generated in vitro were plated onto dentine slices, insulin dose-dependently inhibited pit formation by up to 80%, suggesting a role for insulin in osteoclast function. These data are consistent with an effect of insulin on bone resorption in addition to those previously recognized on bone formation, actions that together result in net bone growth.

Growth hormone deficiency and cardiovascular risk

It is now recognized that growth hormone (GH) deficiency in adults represents a distinct clinical syndrome that encompasses reduced psychological well-being as well as specific metabolic abnormalities. The latter features, which include hypertension, central obesity, insulin resistance, dyslipidaemia and coagulopathy, closely resemble those of metabolic insulin resistance syndrome. The increased cardiovascular morbidity and mortality demonstrated in these GH-deficient (GHD) adults reinforce the close association between the two syndromes. Replacement of GH in GHD adults has resulted in a marked reduction of central obesity and significant reduction in total cholesterol but little change in other risk factors, in particular insulin resistance and dyslipidaemia. The persistent insulin resistance and dyslipidaemia, together with the elevation of plasma insulin levels and lipoprotein (a) with GH replacement in these subjects are of concern. Long-term follow-up data are required to assess the impact of GH replacement on the cardiovascular morbidity and mortality of GHD adults. Further exploration of the appropriateness of the GH dosage regimens currently being employed is also indicated.

Do postmenopausal women with NIDDM have a reduced capacity to deposit and conserve lower-body fat?

OBJECTIVE

To compare regional body fat distribution and sex hormone status of postmenopausal women with NIDDM with those of age- and BMI-matched normoglycemic women.

RESEARCH DESIGN AND METHODS

The regional body fat distribution and sex hormone status of 42 postmenopausal women with NIDDM were compared with those of 42 normoglycemic women matched for age and BMI, who served as control subjects. Body composition was measured by dual-energy X-ray absorptiometry, and sex hormone-binding globulin (SHBG) and testosterone were measured in serum.

RESULTS

Although the levels of total body fat were similar between the two groups, the women with NIDDM had significantly less lower-body fat (LBF) (P < 0.01) than the control subjects matched for age and BMI. This pattern of fat deposition in women with NIDDM was accompanied by an androgenic hormone profile, with decreased SHBG concentration and an increased free androgen index (P < 0.05 and P < 0.01, respectively).

CONCLUSIONS

A reduced capacity to deposit and/or conserve LBF may be an independent factor associated with (or may be a marker of) the metabolic manifestations of the insulin resistance syndrome in women with NIDDM. The possibility that the smaller relative accumulation of LBF is a consequence of the androgenic hormonal profile should be investigated in future studies.

Lipid levels and peripheral vascular disease in diabetic and non-diabetic subjects

Non-insulin dependent diabetes (NIDDM) is associated with an increased risk of peripheral vascular disease (PVD), but within the diabetic population the relationship between lipid profile and PVD has not been clearly defined. In this study we examined the association of lipid parameters and in particular low density lipoprotein (LDL) particle size, with the presence of PVD in subjects with and without NIDDM. 41 NIDDM patients and 31 non-diabetic subjects with PVD in the absence of rest pain or ulceration, defined by ankle-brachial index measurements and duplex scanning, were compared with 41 NIDDM and 31 euglycemic control subjects of comparable age and sex, without PVD. In both groups those with PVD were found to have significantly elevated triglycerides (2.7 [2.2-3.3] versus 1.9 [1.6-2.2] mmol/l; P < 0.05 in the diabetic group and 2.0 [1.6-2.3] versus 1.4 [1.1-1.5] mmol/l; P < 0.05 in the non-diabetic group), decreased apolipoprotein A1 (124 +/- 3 versus 139 +/- 5 mg/dl; P < 0.01 in the diabetic group and 133 +/- 4 versus 147 +/- 4 mg/dl; P < 0.05 in the non-diabetic group) and decreased LDL particle size (25.4 +/- 0.1 versus 25.8 +/- 0.1 nm; P < 0.01 in the diabetic group and 26.0 +/- 0.1 versus 26.3 +/- 0.1 nm; P < 0.05 in the non diabetic group). In the non-diabetic group apolipoprotein[a] (365 [239-554] versus 184 [17-266] U/l; P < 0.01), total cholesterol (6.3 +/- 0.2 versus 5.6 +/- 0.2 mmol/l; P < 0.05), LDL cholesterol (4.1 +/- 0.2 versus 3.6 +/- 0.2 mmol/l; P < 0.05) and apolipoprotein B (146 +/- 8 versus 117 +/- 5 mg/dl; P < 0.05) were also found to be associated with PVD although these associations were not observed in the group with diabetes. In addition, 11 NIDDM subjects and 11 non-diabetic subjects with rest pain or ulceration were compared to the corresponding groups with uncomplicated PVD and had lipid profiles with significantly lower levels of total cholesterol and LDL cholesterol. We conclude that the dyslipidemic profile characterized by increased triglyceride level, decreased apolipoprotein A1 level and small dense LDL is associated with uncomplicated PVD in both NIDDM and non-diabetic subjects.

The effect of norepinephrine on insulin secretion and glucose effectiveness in non-insulin-dependent diabetes

It has previously been shown that in normal subjects, physiological elevation of norepinephrine (NE) impairs insulin sensitivity (Si) but does not influence insulin secretion. The aim of this study was to determine the effect of short-term physiological elevation of NE on insulin secretion, Si, and glucose-mediated glucose disposal, or the glucose effectiveness index (Sg), in non-insulin-dependent diabetes mellitus (NIDDM). Two intravenous glucose tolerance tests (IVGTTs) were performed in eight well-controlled NIDDM patients, using a supplemental exogenous insulin infusion to achieve an approximation of normal endogenous insulin secretion. The IVGTTs were performed in random order after 30 minutes of either the saline (SAL) or NE (25 ng/kg/min) infusions, which were continued throughout the 3-hour IVGTT. Sg and Si were estimated by minimal model analysis of the IVGTT data as previously described. Plasma C-peptide was used to estimate insulin secretion rate using the ISEC program. NE infusion produced approximately a threefold increase in plasma NE, associated with (1) a significant reduction in glucose disposal ([KG] SAL v NE, 0.73 +/- 0.06 v 0.61 +/- 0.06 x 10(-2).min-1, P < .05), (2) no reduction in Si (2.33 +/- 0.8 v 2.62 +/- 0.9 x 10(-4).min-1/mU/L, NS), (3) a reduced mean second-phase insulin secretion rate (1.21 +/- 0.19 v 1.01 +/- 0.16 x 10(-3) pmol/kg/min per mmol/L glucose, P < .05), (4) a significant increase in Sg (0.89 +/- 0.08 v 1.63 +/- 0.2 x 10(-2).min-1, P < .05), and (5) a corresponding increase in glucose effectiveness at zero insulin ([GEZI] 0.55 +/- 0.13 v 1.30 +/- 0.33 x 10(-2).min-1, P < .05). These results show that in contrast to normal subjects, physiological elevation of NE in NIDDM does not result in a reduction in Si, but causes a reduction in glucose disposal related to inhibition of insulin secretion that is only partially compensated for by increased Sg.

Analysis of risk factors for omental herniation associated with removal of peritoneal catheters

BACKGROUND

Peritoneal catheters may be used routinely in children undergoing cardiac surgery. Removal of the catheter is often complicated by omental herniation, which can cause intraperitoneal bleeding, peritonitis, and bowel obstruction. Instillation of saline into the catheter before removal is used in some institutions as a preventive measure, but the practice has never been investigated.

OBJECTIVE

To determine the effectiveness of instilling saline into peritoneal catheters before their removal in reducing the occurrence of omental herniation and to determine risk factors for omental herniation.

METHODS

A total of 404 patients with peritoneal catheters in place were randomized to either the control or the study group. The study group (n = 204) had saline (1 mL/kg; maximum, 10 mL) instilled into the catheter before the catheter was removed; the control group (n = 200) did not. Extrusion or no extrusion of omentum was recorded. Other data collected included the child's weight, the length of time the catheter was in place, whether peritoneal dialysis was performed, and whether the child was pharmacologically paralyzed when the catheter was removed.

RESULTS

Extrusion of omentum occurred in 39% of the study group and in 33% of the controls. Results of logistic regression analysis suggested that omental herniation was more common in smaller children, children whose catheters remained in place longer, and children who were not pharmacologically paralyzed when the catheter was removed.

CONCLUSIONS

Instillation of saline does not appear to reduce the occurrence of omental herniation. Further research into strategies to reduce this complication is recommended.

Analysis of risk factors for omental herniation associated with removal of peritoneal catheters

BACKGROUND: Peritoneal catheters may be used routinely in children undergoing cardiac surgery. Removal of the catheter is often complicated by omental herniation, which can cause intraperitoneal bleeding, peritonitis, and bowel obstruction. Instillation of saline into the catheter before removal is used in some institutions as a preventive measure, but the practice has never been investigated. OBJECTIVE: To determine the effectiveness of instilling saline into peritoneal catheters before their removal in reducing the occurrence of omental herniation and to determine risk factors for omental herniation. METHODS: A total of 404 patients with peritoneal catheters in place were randomized to either the control or the study group. The study group (n = 204) had saline (1 mL/kg; maximum, 10 mL) instilled into the catheter before the catheter was removed; the control group (n = 200) did not. Extrusion or no extrusion of omentum was recorded. Other data collected included the child's weight, the length of time the catheter was in place, whether peritoneal dialysis was performed, and whether the child was pharmacologically paralyzed when the catheter was removed. RESULTS: Extrusion of omentum occurred in 39% of the study group and in 33% of the controls. Results of logistic regression analysis suggested that omental herniation was more common in smaller children, children whose catheters remained in place longer, and children who were not pharmacologically paralyzed when the catheter was removed. CONCLUSIONS: Instillation of saline does not appear to reduce the occurrence of omental herniation. Further research into strategies to reduce this complication is recommended.

Low-density lipoprotein size, high-density lipoprotein concentration, and endothelial dysfunction in non-insulin-dependent diabetes

We examined endothelial function (nitric-oxide mediated) in 29 men with diet-treated non-insulin-dependent (Type 2) diabetes mellitus (NIDDM) and 18 male age-matched controls. Forearm blood flow was measured by venous occlusive plethysmography during intra-arterial administration of acetylcholine (ACh, 7.5 and 15 microg min(-1)) and sodium nitroprusside (SNP, 3 and 10 microg min(-1)). LDL particle size was estimated by non-denaturing gel electrophoresis. Serum lipids, blood pressure, and glycated haemoglobin were also measured. LDL particle size was smaller (p = 0.048) in the diabetic patients than controls. In the diabetic patients, LDL particle size was a significant positive predictor (p = 0.01) of the area under the dose-response curve for ACh, after adjusting for age, HbA1c, systolic BP, and cholesterol (R2 0.20). In stepwise regression including serum lipid and lipoprotein concentrations and LDL particle size, decreased HDL cholesterol was the best predictor of an impaired vasodilatory response to ACh. Vasodilatory responses to sodium nitroprusside were not significantly correlated with LDL particle size or serum lipid and lipoprotein concentrations. We conclude that in men with NIDDM, small, dense LDL particle size is associated with abnormal endogenous release of nitric oxide. The contribution of small, dense LDL particles to the development of endothelial dysfunction and early diabetic vasculopathy may not, however, be as great as decreased HDL cholesterol.

Insulin resistance syndrome in Australian aboriginal people

1. Like many indigenous populations, Australian Aboriginal people have developed high rates of obesity, non-insulin-dependent diabetes mellitus (NIDDM) and cardiovascular and renal disease following the transition from a traditional to an 'urbanized' lifestyle. These conditions tend to cluster as part of the insulin resistance syndrome. 2. The prevalence of overweight people and obesity in Australian Aboriginal populations ranges from 0% in communities with a traditionally orientated lifestyle to well over 50% in the worst affected communities. There is a predominantly central pattern of fat deposition in both men and women, which is associated with greater insulin resistance and cardiovascular risk than is peripheral fat deposition. 3. Data from four previously published, population-based surveys in Aboriginal communities were combined to give a cohort of 1079 subjects of 15 years and older. Several conditions of the insulin resistance syndrome had a strong, positive association with increasing body mass index (BMI): NIDDM (both cross-sectionally and longitudinally), hypertension, dyslipidaemia and albuminuria. Remaining lean (BMI < 20 kg/m2) protected even older Aboriginal people from these conditions to a large extent. 4. Community based programmes to increase physical activity and improve dietary quality are likely to be the major means by which conditions associated with insulin resistance can be prevented in Aboriginal populations.

Insulin receptor expression in bone

Insulin is known to be an important osteotropic hormone. To date, no study has specifically addressed the possibility that insulin receptor expression may be regulated by differentiation in bone. We report a heterogeneous distribution of insulin receptor (IR) within neonatal rat calvaria using a specific monoclonal antibody to the beta-subunit of the rat insulin receptor (CT-1). Specific binding of CT-1 to mature osteoblasts was demonstrated, with little binding over periosteal tissues or osteocytes. Using enzymatically derived subpopulations of calvarial cells, we showed a correlation between alkaline phosphatase activity and insulin-stimulated 2-deoxyglucose (2-DOG) uptake and increased 125I-insulin binding. Since primary calvarial cultures contain many cell types, we compared 125I-insulin binding, insulin-stimulated 2-DOG uptake, and Northern blot analysis of IR mRNA in the clonal preosteoblast-like cell line UMR 201-10B and the mature osteoblast cell line UMR 106-01. It is shown that UMR 106-01 cells possess higher levels of IR mRNA, insulin binding, and insulin-stimulated glucose uptake, and that insulin up-regulated expression of mRNA of the glucose transporter GLUT1 by 3-fold. In contrast, insulin binding was negligible in UMR 201-10B cells, which expressed much lower levels of IR mRNA. UMR 201-10B cells did not possess an insulin-sensitive glucose uptake system, although they express GLUT1 mRNA. These data are consistent with the hypothesis that, as in muscle and fat, insulin receptor expression correlates with the stage of osteoblast differentiation in vivo and in vitro.

Glomerular lipid deposition and proteinuria in a patient with familial dysbetalipoproteinaemia

This report describes a male patient who was found to have proteinuria at age 31. Renal biopsy showed glomerular hypercellularity with enlarged, lipid-filled endocapillary cells. On subsequent lipid analysis there was elevation of cholesterol and triglyceride, with apolipoprotein E genotype E2/E2. The clinical course was complicated by pancreatitis and onset of diabetes. After treatment with gemfibrozil and some improvement of the lipid profile, a second renal biopsy showed marked reduction of the glomerular foam cells, despite an increased level of proteinuria. This case emphasizes the potential role that lipid abnormalities may play in renal dysfunction.

Dexamethasone modulates insulin receptor expression and subcellular distribution of the glucose transporter GLUT 1 in UMR 106-01, a clonal osteogenic sarcoma cell line

Corticosteroids have profound effects on bone metabolism, though the underlying mechanisms remain unclear. They are also known to alter glucose metabolism, in part by induction of insulin resistance. To determine whether corticosteroids impair glucose metabolism in bone cells, we have examined the actions of dexamethasone (DEX) on glucose transport and insulin receptor expression using osteoblast-like UMR 106-01 cells. DEX was shown to inhibit basal 2-deoxyglucose uptake by up to 30% in a time- and dose-dependent manner. It inhibited insulin-stimulated glucose transport by 13%. By Northern and Western blot analysis, DEX was shown to stimulate insulin receptor mRNA and protein by up to 5.6-fold, but it had no effect on expression of the glucose transporter GLUT 1 mRNA or protein under basal conditions. However, DEX augmented insulin-stimulated GLUT 1 mRNA and protein levels. By Scatchard analysis of labelled insulin binding, DEX increased insulin receptor number per cell by 54%. Subcellular fractionation and Western blot analysis demonstrated that DEX caused a redistribution of immunoreactive GLUT 1 from plasma membrane to intracellular microsomes, resulting in a 21% decrease in GLUT 1 at the plasma membrane. These data suggest that (i) DEX impairs basal glucose transport by post-translational mechanisms in UMR 106-01 cells, (ii) DEX increases insulin receptor mRNA, protein and insulin binding and (iii) the inhibition of glucose transport by DEX dominates its effects on the insulin receptor. It is possible that DEX inhibition of glucose transport in osteoblasts may contribute to steroid-induced osteoporosis.

Factors influencing Lp[a]- particle size as determined by gradient gel electrophoresis

This study examined factors influencing the particle diameter of Lp[a]-, the low density lipoprotein (LDL)-like moiety of Lp[a], in 26 subjects chosen to provide a range of Lp[a] and triglyceride levels. Lp[a] and LDL fractions were isolated by vertical density ultracentrifugation. Lp[a] was further purified using a lysine-Sepharose affinity column and Lp[a]- obtained by incubating Lp[a] with dithiothreitol. Lp[a], LDL, and Lp[a]- fractions were run on 3-13% gradient gels to determine particle diameter. Lp[a] size correlated positively with LDL size (r = 0.62; P < 0.001), but the association between Lp[a]- size and LDL size was stronger (r = 0.82; P < 0.0001). Log triglyceride level correlated inversely with Lp[a]- size (r = -0.72; P < 0.0001) and LDL size (r = 0.69; P < 0.0001). HDL cholesterol level correlated positively with Lp[a]- size (r = 0.67; P < 0.0005) and LDL size (r = 0.64; P < 0.0005). The strong correlation between LDL size and Lp[a]- size may be due to extracellular utilization of circulating LDL in the production of Lp[a] or may reflect the same metabolic processes influencing both these particles once Lp[a] has been formed.

Low density lipoprotein particle size in hypopituitary adults receiving conventional hormone replacement therapy

Adults receiving conventional replacement therapy for hypopituitarism are known to have increased cardiovascular mortality. The aim of this study was to assess the lipid profiles of 30 hypopituitary adults compared with 2 case control groups, 1 matched for age, sex, and body mass index (BMI) and the second matched for age and sex only with a BMI representative of the general population. Fasting lipids, lipoproteins, and apoproteins (Apo) were determined by routine methods. Low density lipoprotein (LDL) particle size was determined by nondenaturing gradient gel electrophoresis. LDL size was significantly smaller in the hypopituitary group (25.9 +/- 0.1 nm) than in the BMI-matched (26.2 +/- 0.1 nm; P < 0.05) and standard control (26.3 +/- 0.1 nm; P < 0.01) groups. High density lipoprotein cholesterol levels in the hypopituitary group were significantly lower than those in the BMI-matched control group (1.13 +/- 0.06 vs. 1.34 +/- 0.06 mmol/L; P < 0.05) and the standard control group (1.38 +/- 0.06 mmol/L; P < 0.005). Apo A1 levels were also lower compared with those in the BMI-matched (122 +/- 6 vs. 137 +/- 4 mg/dL; P < 0.05) and the standard (143 +/- 4 mg/dL; P < 0.005) control groups. There was a trend toward higher triglyceride levels when the hypopituitary subjects were compared with the standard control group [1.4 (95% CI, 1.3-2.2) vs. 1.0 (95% CI, 0.9-1.4) mmol/L; P = 0.06]. These differences were more marked in the female subjects studied. No significant differences were noted in total cholesterol, LDL cholesterol, or Apo B levels. We conclude that hypopituitary patients receiving conventional replacement therapy have an atherogenic lipid profile characterized by small dense LDL, decreased high density lipoprotein cholesterol, and increased triglyceride levels, which may contribute to the excess cardiovascular mortality in this group.

Endocrinology and auxology of sibships with non-classical congenital adrenal hyperplasia

The symptoms, auxological characteristics, and stimulated 17-hydroxyprogesterone (17-OHP) concentrations in a group of patients with non-classical 21-hydroxylase deficiency (NCCAH) were compared with those of their siblings. Ten index cases consisting of nine females and one male patient aged 3-33 years and 16 siblings were studied. In the sibling group five subjects were slightly virilised and of these, two females were found to have NCCAH according to their stimulated 17-OHP concentrations. The remaining nine siblings, who were not virilised, all had normal stimulated 17-OHP concentrations. Among the total NCCAH group (index cases and affected siblings) eight patients had the diagnosis made within two years of the onset of symptoms. In four patients diagnosis was delayed until adulthood. In seven patients investigated, bone age was significantly increased before treatment. The mean height and body mass index Z scores of the affected patients as a total group or when divided according to skeletal maturity were not significantly different from either the normal mean or from their unaffected siblings. Virilised siblings of patients with NCCAH should have stimulated 17-OHP levels measured to exclude the disease. Patients with NCCAH do not appear to be at risk of short adult stature despite increased bone age in childhood.

Expression and regulation by insulin of GLUT 3 in UMR 106-01, a clonal rat osteosarcoma cell line

Expression of the glucose transporter GLUT 3 is mainly restricted to neuronal tissues, with lower levels in testis and placenta. In addition, GLUT 3 has recently been reported in neonatal rat calvaria by in situ hybridisation. We report the co-expression of GLUT 1 and GLUT 3 mRNA and protein in UMR 106-01, a clonal osteosarcoma cell line. By semi-quantitative analysis we show that GLUT 3 protein is expressed at levels comparable to GLUT 1. Insulin stimulates glucose uptake in UMR 106-01 cells. GLUT 3 mRNA and protein are increased by chronic (16 h) treatment with insulin, and the increase in GLUT 3 mRNA is not inhibited by cycloheximide. Regulation of GLUT 3 mRNA by insulin has not been previously shown. UMR 106-01 represents a useful model for investigating regulation of GLUT 3 expression.

The role of lipoprotein(a) in the vascular complications of diabetes mellitus

Lipoprotein(a) has been identified as an independent risk factor for atherosclerotic vascular disease in non-diabetic populations. Because of its potential role in the pathogenesis of both microvascular and macrovascular complications in diabetes, there have recently been many reports on lipoprotein(a) in diabetic populations. Some studies indicate an association between elevated lipoprotein(a) and macrovascular disease in non-insulin-dependent diabetes mellitus (NIDDM), but this link has not been found with insulin-dependent diabetes mellitus (IDDM). In IDDM, elevated lipoprotein(a) has been found in groups with diabetic nephropathy and retinopathy, raising the possibility that it plays a causative role. The relationship between glycaemic control and the lipoprotein(a) level has not been fully resolved. Most studies have not found any connection in NIDDM, but some found higher lipoprotein(a) levels in hyperglycaemic IDDM patients. Potentially, lipoprotein(a) is an important factor linking the microvascular and macrovascular complications of diabetes.

Modulation of glucose transport by parathyroid hormone and insulin in UMR 106-01, a clonal rat osteogenic sarcoma cell line

This study characterizes the actions of insulin and parathyroid hormone (PTH) on the glucose transport system in the rat osteogenic sarcoma cell line UMR 106-01, which expresses a number of features of the osteoblast phenotype. Using [1,2-3H]2-deoxyglucose (2-DOG) as a label, UMR 106-01 cells were shown to possess a glucose transport system which was enhanced by insulin. In contrast, PTH influenced glucose transport in a biphasic manner with a stimulatory effect at 1 h and a more potent inhibitory effect at 16 h on basal and insulin-stimulated 2-DOG transport. To explore the mechanism of PTH action, a direct agonist of cAMP-dependent protein kinase (PKA) was tested. 8-Bromo-cAMP had no acute stimulatory effect but inhibited basal and insulin-stimulated 2-DOG transport at 16 h. This result suggested that the prolonged, but not the acute, effect of PTH was mediated by the generation of cAMP. Further studies with the cell line UMR 4-7, a UMR 106-01 clone stably transfected with an inducible mutant inactive regulatory subunit of PKA, confirmed that the inhibitory but not the stimulatory effect of PTH was mediated by the PKA pathway. Northern blot data indicated that the prolonged inhibitory effects of PTH and 8-bromo-cAMP on glucose transport were likely to be mediated in part by reduction in the levels of GLUT1 (HepG2/brain glucose transporter) mRNA.

Retinoic acid stimulates glucose transporter expression in L6 muscle cells

Factors that regulate the tissue specific and developmental expression of the GLUT4 gene, whose transcribed protein is primarily responsible for mediating insulin stimulated glucose transport, are poorly defined. In this study we examined the effects of retinoic acid, a circulating factor that can promote cellular differentiation, on glucose uptake and glucose transporter expression in cultured L6 muscle cells. At the myoblast stage, treatment with 1 microM retinoic acid for 24 h increased both 1 h and 8 h insulin stimulated uptake of 2-deoxyglucose by more than twofold. A dose and time dependent effect of retinoic acid on 8 h insulin stimulated 2-deoxyglucose uptake was observed at both the myoblast and myocyte stage. Comparatively little effect from retinoic acid treatment was found on basal uptake at either stage. In myoblast cells, retinoic acid increased the content of GLUT4 mRNA in a dose and time dependent manner, an effect that was partially attenuated by insulin. In myocytes retinoic acid increased GLUT4 mRNA levels to 2.3 times basal. Nuclear run-on studies indicate that the increased GLUT4 mRNA represents enhanced transcriptional activity. The results suggest a role for retinoic acid in regulation of expression of the GLUT 4 gene in muscle cells.