Development of a prediction score (ThyroCOVID) for identifying abnormal thyroid function in COVID-19 patients

PURPOSE

Thyroid dysfunction in COVID-19 carries clinical and prognostic implications. In this study, we developed a prediction score (ThyroCOVID) for abnormal thyroid function (TFT) on admission amongst COVID-19 patients.

METHODS

Consecutive COVID-19 patients admitted to Queen Mary Hospital were prospectively recruited during July 2020-May 2021. Thyroid-stimulating hormone (TSH), free thyroxine (fT4) and free triiodothyronine (fT3) were measured on admission. Multivariable logistic regression analysis was performed to identify independent determinants of abnormal TFTs. ThyroCOVID was developed based on a clinical model with the lowest Akaike information criteria.

RESULTS

Five hundred and forty six COVID-19 patients were recruited (median age 50 years, 45.4% men, 72.9% mild disease on admission). 84 patients (15.4%) had abnormal TFTs on admission. Patients with abnormal TFTs were more likely to be older, have more comorbidities, symptomatic, have worse COVID-19 severity, higher SARS-CoV-2 viral loads and more adverse profile of acute-phase reactants, haematological and biochemical parameters. ThyroCOVID consisted of five parameters: symptoms (malaise), comorbidities (ischaemic heart disease/congestive heart failure) and laboratory parameters (lymphocyte count, C-reactive protein, and SARS-CoV-2 cycle threshold values). It was able to identify abnormal TFT on admission with an AUROC of 0.73 (95% CI 0.67-0.79). The optimal cut-off of 0.15 had a sensitivity of 75.0%, specificity of 65.2%, negative predictive value of 93.5% and positive predictive value of 28.1% in identifying abnormal TFTs on admission amongst COVID-19 patients.

CONCLUSION

ThyroCOVID, a prediction score to identify COVID-19 patients at risk of having abnormal TFT on admission, was developed based on a cohort of predominantly non-severe COVID-19 patients.

Potential role of fibroblast growth factor 21 in the deterioration of bone quality in impaired glucose tolerance

PURPOSE

Findings on trabecular bone score (TBS), an index of bone quality, have been reported in prediabetes defined by impaired fasting glucose or HbA1c. Here, we assessed the bone mineral density (BMD) and TBS in prediabetes individuals with impaired glucose tolerance (IGT), and investigated the association of these bone parameters with serum levels of fibroblast growth factor 21 (FGF21), a hormone implicated in bone metabolism and with higher levels in IGT.

METHODS

Chinese postmenopausal women aged 55-80 years, without diabetes, were recruited from the Hong Kong Cardiovascular Risk Factor Prevalence Study in 2016-2018. Normal glucose tolerance (NGT) was defined by fasting glucose < 5.6 mmol/L and 2-h plasma glucose (2hG) < 7.8 mmol/L, and IGT by 2hG 7.8-11 mmol/L. Serum levels of FGF21 and other bone metabolism regulators were measured. Insulin sensitivity was assessed by the Matsuda index. Independent determinants of TBS were evaluated using multivariable stepwise linear regression.

RESULTS

173 individuals with NGT and 73 with IGT were included. TBS was lower in those with IGT compared to those with NGT, while BMD was comparable. Individuals with IGT had significantly higher serum FGF21 levels, which in turn showed an independent inverse relationship with TBS, attenuated after inclusion of the Matsuda index. Serum FGF21 levels, however, did not correlate with BMD.

CONCLUSION

Among Chinese postmenopausal women, bone quality was worse in IGT, despite comparable bone density. FGF21 levels showed a significant independent inverse relationship with TBS, partly attributed to insulin resistance. Whether FGF21 contributes to the impaired bone quality in IGT remains speculative.

A clinical prediction score using age at diagnosis and saline infusion test parameters can predict aldosterone-producing adenoma from idiopathic adrenal hyperplasia

PURPOSE

Accurate subtyping of the primary aldosteronism into aldosterone-producing adenoma (APA) and idiopathic adrenal hyperplasia (IAH) is important to direct for specific treatment modalities. The objective of the study was to compare the clinical and biochemical parameters of APA and IAH patients to derive a Clinical Prediction Score reliably predicting APA from IAH.

METHODS

This was a retrospective multi-centre study recruiting 38 APA patients and 42 IAH patients from four major hospitals in Hong Kong using database from Surgical Outcomes Monitoring and Improvement Programme and Clinical Data Analysis and Reporting System. Their clinical and biochemical parameters were evaluated.

RESULTS

Patients in APA group were younger than IAH group (mean age 48.6 ± 9.2 vs. 57.1 ± 7.3 years old, p < 0.001), had more suppressed renin before saline infusion in saline infusion test (SIT) (median 0.19 [IQR 0.15-0.37] vs. 0.39 [IQR 0.19-0.69] ng/mL/h, p = 0.01), and higher aldosterone level after saline infusion in SIT (median 674 [IQR 498-1000] vs. 327 [IQR 242-483] pmol/L, p < 0.001). A clinical prediction score using three parameters was devised, comprising age at diagnosis < 50 years, PRA before saline infusion in SIT ≤ 0.26 ng/mL/h, and aldosterone level after saline infusion in SIT ≥ 424 pmol/L. A score of 2 would predict APA with a sensitivity of 84.2% and specificity of 88.1%, and a score of 3 would predict APA with a sensitivity of 31.6% and specificity of 100%.

CONCLUSIONS

Clinical Prediction Score based on the combination of age at diagnosis, PRA, and aldosterone level in the saline infusion tests could reliably predict APA from IAH.

Annual direct medical costs associated with diabetes-related complications in the event year and in subsequent years in Hong Kong

AIM

To develop models to estimate the direct medical costs associated with diabetes-related complications in the event year and in subsequent years.

METHODS

The public direct medical costs associated with 13 diabetes-related complications were estimated among a cohort of 128 353 people with diabetes over 5 years. Private direct medical costs were estimated from a cross-sectional survey among 1825 people with diabetes. We used panel data regression with fixed effects to investigate the impact of each complication on direct medical costs in the event year and subsequent years, adjusting for age and co-existing complications.

RESULTS

The expected annual public direct medical cost for the baseline case was US$1,521 (95% CI 1,518 to 1,525) or a 65-year-old person with diabetes without complications. A new lower limb ulcer was associated with the biggest increase, with a multiplier of 9.38 (95% CI 8.49 to 10.37). New end-stage renal disease and stroke increased the annual medical cost by 5.23 (95% CI 4.70 to 5.82) and 5.94 (95% CI 5.79 to 6.10) times, respectively. History of acute myocardial infarction, congestive heart failure, stroke, end-stage renal disease and lower limb ulcer increased the cost by 2-3 times. The expected annual private direct medical cost of the baseline case was US$187 (95% CI 135 to 258) for a 65-year-old man without complications. Heart disease, stroke, sight-threatening diabetic retinopathy and end-stage renal disease increased the private medical costs by 1.5 to 2.5 times.

CONCLUSIONS

Wide variations in direct medical cost in event year and subsequent years across different major complications were observed. Input of these data would be essential for economic evaluations of diabetes management programmes.

Serum calcium and incident diabetes: an observational study and meta-analysis

The study aimed to prospectively evaluate if serum calcium is related to diabetes incidence in Hong Kong Chinese. The results showed that serum calcium has a significant association with increased risk of diabetes. The result of meta-analysis reinforced our findings.

INTRODUCTION

This study aimed to evaluate the association of serum calcium, including serum total calcium and albumin-corrected calcium, with incident diabetes in Hong Kong Chinese.

METHODS

We conducted a retrospective cohort study in 6096 participants aged 20 or above and free of diabetes at baseline. Serum calcium was measured at baseline. Incident diabetes was determined from several electronic databases. We also searched relevant databases for studies on serum calcium and incident diabetes and conducted a meta-analysis using fixed-effect modeling.

RESULTS

During 59,130.9 person-years of follow-up, 631 participants developed diabetes. Serum total calcium and albumin-corrected calcium were associated with incident diabetes in the unadjusted model. After adjusting for demographic and clinical variables, the association remained significant only for serum total calcium (hazard ratio (HR), 1.32 (95 % confidence interval (CI), 1.02-1.70), highest vs. lowest quartile). In a meta-analysis of four studies including the current study, both serum total calcium (pooled risk ratio (RR), 1.38 (95 % CI, 1.15-1.65); I (2) = 5 %, comparing extreme quantiles) and albumin-corrected calcium (pooled RR, 1.29 (95 % CI, 1.03-1.61); I (2) = 0 %, comparing extreme quantiles) were associated with incident diabetes. Penalized regression splines showed that the association of incident diabetes with serum total calcium and albumin-correlated calcium was non-linear and linear, respectively.

CONCLUSIONS

Elevated serum calcium concentration is associated with incident diabetes. The mechanism underlying this association warrants further investigation.

Genetics of Apparently Sporadic Pheochromocytoma and Paraganglioma in a Chinese Population

Identification of germline mutation in patients with apparently sporadic pheochromocytomas and paragangliomas is crucial. Clinical indicators, which include young age, bilateral or multifocal, extra-adrenal, malignant, or recurrent tumors, predict the likelihood of harboring germline mutation in Caucasian subjects. However, data on the prevalence of germline mutation, as well as the applicability of these clinical indicators in Chinese, are lacking. We conducted a cross-sectional study at a single endocrine tertiary referral center in Hong Kong. Subjects with pheochromocytomas and paragangliomas were evaluated for the presence of germline mutations involving 10 susceptibility genes, which included NF1, RET, VHL, SDHA, SDHB, SDHC, SDHD, TMEM 127, MAX, and FH genes. Clinical indicators were assessed for their association with the presence of germline mutations. Germline mutations, 2 being novel, were found in 24.4% of the 41 Chinese subjects recruited and 11.4% among those with apparently sporadic presentation. The increasing number of the afore-mentioned clinical indicators significantly correlated with the likelihood of harboring germline mutation in one of the 10 susceptibility genes. (r=0.757, p=0.026). The presence of 2 or more clinical indicators should prompt genetic testing for germline mutations in Chinese subjects. In conclusion, our study confirmed that a significant proportion of Chinese subjects with apparently sporadic pheochromocytoma and paraganglioma harbored germline mutations and these clinical indicators identified from Caucasians series were also applicable in Chinese subjects. This information will be of clinical relevance in the design of appropriate genetic screening strategies in Chinese populations.

A middle-aged man with increasing body fat

A 51-year-old man was referred for evaluation of gradual increase in body fat over bilateral arms, chest and abdomen for 6 months. He was a non-smoker and he drank at least four bottles of beer daily since the age of 18. There was no significant past medical history or any family history of obesity or endocrine diseases. Physical examination showed localized large bulk of fat over the neck, both arms and mammary regions, abdomen, and back (Figs  and ). The lower limbs and buttock were relatively spared. There was telangiectasia over the face and chest wall, but no palmar erythema nor finger clubbing. The liver span was normal, and the spleen tip was palpated 2 cm below the costal margin. Examination of the cardiovascular, respiratory and neurological system was normal. [Figure: see text] [Figure: see text] Blood tests showed thrombocytopenia (platelet 140 × 10(9)  L(-1) [normal: 170-380 × 10(9)  L(-1) ]) and liver function derangement (bilirubin 27 μmol L(-1) , ALP 298 U L(-1) , ALT 127 U L(-1) , AST 165 U L(-1) , GGT 1353 U L(-1) , albumin 33 g L(-1) and globulin 42 g L(-1) ). His clotting profile and renal functions were normal. His hepatitis B surface antigen was positive, but his HBV DNA was <60 copies per mL. Fasting glucose was 5.0 mmol L(-1) . HbA1c was 5.6%. His lipid profile was satisfactory with total cholesterol of 2.9 mmol L(-1) , triglycerides 1.0 mmol L(-1) , HDL-C 1.37 mmol L(-1) and LDL-C 1.1 mmol L(-1) . Ultrasound of the abdomen showed normal-sized liver with coarsened liver parenchymal echogenicity. The spleen was enlarged to 14 cm. This middle-aged man suffered from multiple symmetric lipomatosis and alcoholic liver disease. Dual-energy X-ray showed 1746 gm (40.1%), 1498 gm (32.8%) and 8322 gm (26.8%) fat over the left arm, right arm and trunk, respectively. The legs were unaffected with 1703 gm (19.4%) and 1627 gm (17.7%) fat over the left and right sides, respectively. The patient was advised to stop drinking and he declined surgical treatment.

Possible FRAX-based intervention thresholds for a cohort of Chinese postmenopausal women

SUMMARY

A total of 2,266 postmenopausal Chinese women were followed for 4.5 years to determine the incidence of new fractures. The positive predictive value, negative predictive value, sensitivity and specificity of different treatment strategies were compared. Using a fixed optimal threshold calculated from receiver operating characteristics (ROC) curve had the highest sensitivity but lowest specificity.

INTRODUCTION

There is no specific intervention threshold based on FRAX to guide treatment for Asian populations. This prospective study sought to determine the impact of applying different intervention thresholds to a cohort of Chinese postmenopausal women.

METHODS

This study was part of the Hong Kong Osteoporosis Study. A total of 2,266 treatment-naïve postmenopausal women underwent clinical risk factor and BMD assessments. The subjects were followed to assess fractures. We calculated the FRAX probability of major osteoporotic fractures corresponding to women with prior fractures but no other clinical risk factors. Different treatment strategies which include treating women with prior fractures, women with age-specific FRAX probability corresponding to those with prior fractures, women with osteoporosis as well as women with FRAX probability above a fixed cut-off based on optimizing sensitivity and specificity on the ROC curve were compared.

RESULTS

The mean age at baseline was 62.1 ± 8.5 years, and the mean follow-up time was 4.5 ± 2.8 years. One hundred six new major osteoporotic fractures were reported. An optimal (FRAX, with BMD) cut-off point of 9.95 % was identified. All strategies had negative predictive value of >90 %. Using a fixed cut-off had the highest sensitivity (62.3 %) but lowest specificity (73.5 %) and positive predictive value (10.3 %). Using a fixed cut-off would direct treatment from younger women with lower absolute risk to elderly women with higher absolute risk.

CONCLUSION

Targeting only women with prior fractures is unlikely to reduce fracture burden. Other treatment strategies with higher sensitivity need to be considered but they have different shortcomings.

Impact of serum amyloid A on cellular cholesterol efflux to serum in type 2 diabetes mellitus

OBJECTIVE

Serum amyloid A (SAA) is an acute phase response protein and has apolipoprotein properties. Since type 2 diabetes is associated with chronic subclinical inflammation, the objective of this study is to investigate the changes in SAA level in type 2 diabetic patients and to evaluate the relationship between SAA and the capacity of serum to induce cellular cholesterol efflux via the two known cholesterol transporters, scavenger receptor class B type I (SR-BI) and ATP-binding cassette transporter G1 (ABCG1).

METHODS

264 patients with type 2 diabetes mellitus (42% with normoalbuminuria, 30% microalbuminuria, and 28% proteinuria) and 275 non-diabetic controls were recruited. SAA was measured by ELISA. SR-BI and ABCG1-mediated cholesterol efflux to serum were determined by measuring the transfer of [(3)H]cholesterol from Fu5AH rat hepatoma cells expressing SR-BI and from human ABCG1-transfected CHO-K1 cells to the medium containing the tested serum respectively.

RESULTS

SAA was significantly increased in diabetic patients with incipient or overt nephropathy. Both SR-BI and ABCG1-mediated cholesterol efflux to serum were significantly impaired in all three groups of diabetic patients (p < 0.01). SAA inversely correlated with SR-BI-mediated cholesterol efflux (r = -0.36, p < 0.01) but did not correlate with ABCG1-mediated cholesterol efflux. Stepwise linear regression analysis showed that HDL, the presence or absence of diabetes, and log(SAA) were significant independent determinants of SR-BI-mediated cholesterol efflux to serum.

CONCLUSION

SAA was increased in type 2 diabetic patients with incipient or overt nephropathy, and SAA was associated with impairment of SR-BI-mediated cholesterol efflux to serum.

Effect of insulin on the soluble receptor for advanced glycation end products (RAGE)

AIMS

The receptor for advanced glycation end products (RAGE) plays an important role in the pathogenesis of diabetic complications. RAGE transcript splicing generates a number of isoforms, including a full-length membrane-bound receptor and a soluble isoform, endogenous secretory RAGE (esRAGE). Soluble forms of the receptor (sRAGE) can also be formed by ectodomain shedding of the membrane-associated receptor. We have evaluated serum levels of sRAGE and esRAGE in Chinese patients with Type 1 diabetes and investigated the effect of insulin on the generation of esRAGE and sRAGE in vitro.

METHODS

Serum sRAGE and esRAGE were measured by ELISA. The in vitro effect of insulin was investigated by incubating THP-1 macrophages with insulin and RAGE isoforms in cell lysate and conditioned media determined.

RESULTS

In patients with diabetes, both serum esRAGE and sRAGE were significantly higher than in age-matched healthy subjects without diabetes. In vitro, insulin increased esRAGE and total RAGE isoform expression in cell lysate on a western blot, and reverse transcription-polymerase chain reaction showed an increase in esRAGE and full-length RAGE mRNA. This was accompanied by an increase in esRAGE and sRAGE in cell conditioned media. Pretreatment of THP-1 cells with a general metalloproteinase inhibitor GM6001 significantly reduced the production of sRAGE, suggesting that insulin also increased the cleavage of full-length cell surface RAGE to form sRAGE.

CONCLUSIONS

Chinese patients with Type 1 diabetes have higher serum levels of esRAGE and sRAGE. In vitro, insulin not only increases both full-length RAGE and esRAGE expression, but can also stimulate the shedding of sRAGE from the membrane-bound receptor.

Association of CDX1 binding site of periostin gene with bone mineral density and vertebral fracture risk

SUMMARY

Periostin (POSTN) as a regulator of osteoblast differentiation and bone formation may affect susceptibility to osteoporosis. This study suggests POSTN as a candidate gene for bone mineral density (BMD) variation and vertebral fracture risk, which could better our understanding about the genetic pathogenesis of osteoporosis and will be useful in clinic in the future.

INTRODUCTION

The genetic determination of osteoporosis is complex and ill-defined. Periostin (POSTN), an extracellular matrix secreted by osteoblasts and a regulator of osteoblast differentiation and bone formation, may affect susceptibility to osteoporosis.

METHODS

We adopted a tag-single nucleotide polymorphism (SNP) based association method followed by imputation-based verification and identification of a causal variant. The association was investigated in 1,572 subjects with extreme-BMD and replicated in an independent population of 2,509 subjects. BMD was measured by dual X-ray absorptiometry. Vertebral fractures were identified by assessing vertebral height from X-rays of the thoracolumbar spine. Association analyses were performed with PLINK toolset and imputation analyses with MACH software. The top imputation finding was subsequently validated by genotyping. Interactions between POSTN and another BMD-related candidate gene sclerostin (SOST) were analyzed using MDR program and validated by logistical regression analyses. The putative transcription factor binding with target sequence was confirmed by electrophoretic mobility shift assay (EMSA).

RESULTS

Several SNPs of POSTN were associated with BMD or vertebral fractures. The most significant polymorphism was rs9547970, located at the -2,327 bp upstream (P = 6.8 × 10(-4)) of POSTN. Carriers of the minor allele G per copy of rs9547970 had 1.33 higher risk of vertebral fracture (P = 0.007). An interactive effect between POSTN and SOST upon BMD variation was suggested (P < 0.01). A specific binding of CDX1 to the sequence of POSTN with the major allele A of rs9547970 but not the variant G allele was confirmed by EMSA.

CONCLUSIONS

Our results suggest POSTN as a candidate gene for BMD variation and vertebral fracture risk.

Reverse cholesterol transport in type 2 diabetes mellitus

High-density lipoprotein (HDL) plays an important protective role against atherosclerosis, and the anti-atherogenic properties of HDL include the promotion of cellular cholesterol efflux and reverse cholesterol transport (RCT), as well as antioxidant, anti-inflammatory and anticoagulant effects. RCT is a complex pathway, which transports cholesterol from peripheral cells and tissues to the liver for its metabolism and biliary excretion. The major steps in the RCT pathway include the efflux of free cholesterol mediated by cholesterol transporters from cells to the main extracellular acceptor HDL, the conversion of free cholesterol to cholesteryl esters and the subsequent removal of cholesteryl ester in HDL by the liver. The efficiency of RCT is influenced by the mobilization of cellular lipids for efflux and the intravascular remodelling and kinetics of HDL metabolism. Despite the increased cardiovascular risk in people with type 2 diabetes, current knowledge on RCT in diabetes is limited. In this article, abnormalities in RCT in type 2 diabetes mellitus and therapeutic strategies targeting HDL and RCT will be reviewed.

Thiazolidinedione increases serum soluble receptor for advanced glycation end-products in type 2 diabetes

AIMS/HYPOTHESIS

Interfering with the activation of receptor for AGE (RAGE) by using a soluble form of the AGE receptor (sRAGE) prevents or ameliorates the vascular complications of diabetes in experimental studies. Relatively little is known about factors that influence endogenous circulating sRAGE in humans. We investigated the impact of improving glycaemic control on serum total sRAGE and endogenous secretory RAGE (esRAGE), a splice variant of sRAGE, and compared the effect of rosiglitazone with that of sulfonylurea.

METHODS

A randomised, open-label, parallel group study was performed with 64 participants randomised to receive add-on therapy with either rosiglitazone or sulfonylurea. Serum total sRAGE and esRAGE and metabolic parameters were measured before and after 6 months of treatment.

RESULTS

At 6 months, both rosiglitazone and sulfonylurea resulted in a significant reduction in HbA(1c), fasting glucose and AGE. However, significant increases in total sRAGE and esRAGE were only seen in the rosiglitazone group. As a result, serum esRAGE was higher in the rosiglitazone group than in the sulfonylurea group at 6 months (p < 0.01), whereas the differences in sRAGE between the two groups did not reach statistical significance. Stepwise linear regression analysis showed that treatment modality made a greater contribution than the changes in HbA(1c) to the subsequent changes in esRAGE levels at 6 months.

CONCLUSIONS/INTERPRETATION

Treating type 2 diabetic patients with thiazolidinedione can increase circulating levels of esRAGE and sRAGE. Whether modulation of circulating sRAGE has a beneficial effect on diabetic complications will have to be evaluated in long-term prospective studies.

Association between serum levels of soluble receptor for advanced glycation end products and circulating advanced glycation end products in type 2 diabetes

AIMS/HYPOTHESIS

Activation of the receptor for advanced glycation end products (RAGE, also known as AGE-specific receptor [AGER]) has been implicated in the development of diabetic vascular complications. Blockade of RAGE using a soluble form of the receptor (sRAGE) suppressed vascular hyperpermeability and atherosclerosis in animal models. Since little is known about the regulation of endogenous sRAGE levels, we determined whether serum sRAGE is influenced by circulating AGEs and the severity of nephropathy in type 2 diabetic patients.

MATERIALS AND METHODS

We recruited 150 healthy control and 318 diabetic subjects. Diabetic subjects were subdivided into those with proteinuria, microalbuminuria or normoalbuminuria. Serum sRAGE was assayed by ELISA and serum AGEs by competitive ELISA using a polyclonal rabbit antiserum raised against AGE-RNase.

RESULTS

Diabetic subjects had higher sRAGE (1,029.5 pg/ml [766.1-1,423.0] interquartile range vs 1,002.6 [726.5-1,345.3], p<0.05) and AGEs (4.07+/-1.13, SD, unit/ml vs 3.39+/-1.05, p<0.01) than controls. Proteinuric subjects had the highest sRAGE levels and there was a significant trend between the severity of nephropathy and sRAGE (p=0.01). In diabetic subjects, serum log(sRAGE) correlated with AGEs (r=0.27, p<0.001), log(plasma creatinine) (r=0.31, p<0.001), log(urine AER) (r=0.24, p<0.01) and log(triglycerides) (r=0.15, p<0.01). On stepwise linear regression analysis, AGEs and creatinine levels were the main independent determinants of sRAGE concentration.

CONCLUSIONS/INTERPRETATION

Serum sRAGE levels and circulating AGEs are associated with the severity of nephropathy in type 2 diabetic patients. Prospective studies are required to determine whether endogenous sRAGE potentially influences the development of diabetic vascular complications.

Plasma apolipoprotein E concentration is an important determinant of phospholipid transfer protein activity in type 2 diabetes mellitus

BACKGROUND

Phospholipid transfer protein (PLTP) transfers phospholipids between lipoproteins and plays an important role in HDL metabolism. PLTP exists as a high-activity and a low-activity form in the circulation. In vitro studies have shown that apolipoprotein (apo) E is involved in maintaining PLTP in the active form, while the low-activity form is associated with apo AI. We have therefore investigated whether plasma apo AI, B and E concentrations are important determinants of plasma PLTP activity in type 2 diabetes, a condition associated with increased plasma PLTP activity.

METHODS

Plasma PLTP activity was assayed by measuring the transfer of radiolabelled phosphatidylcholine from liposomes to HDL; apo AI and B by rate nephelometry and apo E by a 2-point turbidimetric assay.

RESULTS

Type 2 diabetic patients (n = 230) had higher PLTP activity than controls (n = 97) (2374 +/- 628 nmol/mL/h versus 1862 +/- 585 respectively, p < 0.01). They also had increased fasting triglyceride and low HDL. Plasma apo B (p < 0.01) and apo E (p < 0.05) were increased, whereas apo AI was reduced (p < 0.01). Univariate analysis showed that plasma PLTP activity correlated mainly with apolipoproteins AI and E. Stepwise regression analysis showed that apo E was the main determinant of plasma PLTP activity, accounting for 23% of its variability in the diabetic subjects and 8% in the controls respectively.

CONCLUSIONS

The associations between plasma apo AI and E concentrations and PLTP activity suggest that these apolipoproteins are important regulators of PLTP activity in vivo. The increase in PLTP activity in type 2 diabetes is partly related to the changes in these apolipoproteins.

Determinants of postprandial triglyceride and remnant-like lipoproteins in type 2 diabetes

BACKGROUND

Postprandial changes in remnant-like lipoprotein particles (RLP) contribute to the severity of coronary heart disease in type 2 diabetes. Since the determinants of postprandial response in RLP are not well understood, this study investigated the roles of fasting triglyceride, apolipoprotein (apo) E polymorphism and insulin resistance in a group of overweight/obese Chinese type 2 diabetic subjects.

METHODS

Postprandial triglyceride (TG) and RLP-cholesterol (RLP-C) were determined after a mixed meal containing 70-g fat at 2-h intervals for 8 h in 32 normotriglyceridemic (NTG) and 31 hypertriglyceridemic (HTG) subjects. RLP-C was measured using an immunoseparation assay and apo E genotypes using polymerase chain reaction and restriction mapping. Insulin resistance was defined as homeostasis model assessment index (HOMA-IR).

RESULTS

The HTG subjects had greater postprandial increase in TG and RLP-C than NTG (p < 0.001), but there were no significant differences in HOMA-IR and apo E allele frequencies. Subjects who were non-E3-carriers had the largest postprandial increment in TG and RLP-C. On stepwise linear regression analysis, log(HOMA-IR) was only an independent determinant of fasting TG but not postprandial TG or RLP-C. The major determinants of fasting and postprandial RLP-C were fasting TG and apo E genotype, accounting for 53 and 6% of the variance of fasting RLP-C (p < 0.01) and 31 and 13% of the variance of postprandial RLP-C respectively (p < 0.01).

CONCLUSIONS

Insulin resistance is mainly a determinant of fasting triglyceride in Chinese type 2 diabetic subjects, whereas apo E genotype is a better predictor of both fasting and postprandial concentrations of RLP.

Plasma phospholipid transfer protein activity and subclinical inflammation in type 2 diabetes mellitus

Phospholipid transfer protein (PLTP) transfers phospholipids between lipoproteins, and plays an essential role in HDL metabolism. The regulation of PLTP is poorly understood and recent evidence suggests that PLTP activity increases during acute-phase response. Since type 2 diabetes is associated with chronic subclinical inflammation, the objective is to determine whether inflammation modulates PLTP in diabetes. Plasma PLTP activity was assayed by measuring the transfer of radiolabeled phosphatidylcholine from liposomes to HDL and high-sensitivity C-reactive protein (CRP) by immunoturbidimetric assay in 280 type 2 diabetic patients and 105 controls. Plasma PLTP activity (2364+/-651 nmol/ml/h versus 1880+/-586 nmol/ml/h in control, mean +/- S.D., P <0.01) and CRP (1.64(0.89-3.23)mg/l versus 0.99(0.53-2.23 mg/l, median (interquartile range), P<0.01) were increased in diabetic subjects. PLTP activity correlated significantly with age, BMI, HbA1c, log(CRP) and apolipoprotein AI and B in diabetic subjects. General linear model analysis showed that only apolipoprotein AI, age, BMI, and log(CRP) were independent determinants of PLTP activity. In conclusion, PLTP activity is increased in diabetes and apolipoprotein AI is a major determinant of PLTP activity. There is also an independent association between CRP and PLTP activity, suggesting that subclinical inflammation may influence PLTP activity in diabetes.

Hypoadiponectinemia is associated with impaired endothelium-dependent vasodilation

Adiponectin may have an antiatherogenic effect by reducing endothelial activation. We hypothesized that plasma adiponectin levels were correlated with endothelial function. Plasma adiponectin level was determined by an in-house RIA assay using a rabbit polyclonal antibody in 73 type 2 diabetic patients and 73 controls. Endothelium-dependent and independent vasodilation of the brachial artery was measured by high-resolution vascular ultrasound. Plasma adiponectin level was lower in diabetic patients than in controls (4.73 +/- 1.96 vs. 7.69 +/- 2.80 microg/ml, respectively; P < 0.001), and they also had impaired endothelium-dependent (5.6 +/- 3.6 vs. 8.6 +/- 4.5%, respectively; P < 0.001) and -independent vasodilation (13.3 +/- 4.9 vs. 16.5 +/- 5.6%, respectively; P < 0.001). Plasma adiponectin correlated with endothelium-dependent vasodilation in controls (P = 0.02) and diabetic patients (P = 0.04). On general linear-model univariate analysis, brachial artery diameter, the presence of diabetes, plasma adiponectin, and high-density lipoprotein were significant independent determinants of endothelium-dependent vasodilation. In vitro experiments showed that endothelial cells expressed adiponectin receptors, and adiponectin increased nitric oxide production in human aortic endothelial cells. In conclusion, low plasma adiponectin level is associated with impaired endothelium-dependent vasodilation, and the association is independent of diabetes mellitus. Adiponectin may act as a link between adipose tissue and the vasculature.

Effects of treatment with Sandostatin LAR on small dense LDL and remnant-like lipoproteins in patients with acromegaly

OBJECTIVE

Acromegalic patients have been shown to have an increase in the concentrations of small dense low-density lipoprotein (LDL) and remnant-like lipoprotein particles (RLP). These lipoproteins are atherogenic and may contribute to the cardiovascular risk of these patients. The aim of this study was to determine whether treatment of acromegaly using Sandostatin LAR could lower these atherogenic lipoproteins.

METHODS

Fourteen patients with active acromegaly were recruited and Sandostatin LAR, a long-acting somatostatin analogue, was given every 4 weeks by intramuscular injection for 6 months. Fasting lipids, lipoproteins, lipolytic enzymes were determined at baseline, 12 and 24 weeks after treatment. Small dense LDL was measured using density gradient ultracentrifugation and RLP-cholesterol (RLP-C) by an immunoseparation assay.

RESULTS

There was already a marked reduction in GH and IGF-1 by week 8 and, in all subjects, IGF-1 levels within their respective age-specific normal range were achieved. At week 12, plasma triglyceride significantly decreased (P < 0.01) and both HDL2 (P < 0.01) and HDL3 (P < 0.01) subfractions increased. A reduction was seen in small dense LDL concentration (P < 0.05) and RLP-C (P < 0.05). Lipoprotein lipase (LPL) activity increased (P < 0.01) and the magnitude of the increase in LPL activity correlated with the increase in HDL at 3 months (r = 0.55, P < 0.05) but not with the changes in plasma triglyceride, small dense LDL or RLP-C. The improvement in plasma lipids and lipoproteins persisted until the end of the study.

CONCLUSION

Sandostatin LAR is effective in the treatment of acromegaly and is associated with favourable changes in plasma lipids and a reduction in small dense LDL and RLP-C.

Multiple endocrine neoplasia type 1 (MEN1): genetic and clinical analysis in the Southern Chinese

OBJECTIVE

Multiple endocrine neoplasia type 1 (MEN1) is characterized by a triad of neoplasia affecting the parathyroid glands, enteropancreatic endocrine tissue and the anterior pituitary gland.

DESIGN

In order to define the prevalence of MEN1 germ-line mutations in Southern Chinese patients with MEN1 syndrome, we performed direct sequencing of the entire open reading frame of the MEN1 gene for 12 index patients and their first-degree relatives.

RESULTS

Six patients had familial MEN1 syndrome and six had apparently sporadic disease. Nine different germ-line mutations at the MEN1 gene were identified, including three novel mutations [248-249delTT in exon 2, K559X(AAG --> TAG) in exon 10 and IVS 2nt + 2(G --> T) in intron 2]. All patients with familial MEN1 syndrome were heterozygous carriers of a germ-line mutation and MEN1-related disorders were only evident in their first-degree relatives who also carried the mutation. All patients with an enteropancreatic lesion were mutation carriers and the absence of mutation in three apparently sporadic MEN1 patients with only hyperparathyroidism and pituitary microadenoma might represent the presence of MEN1 phenocopy.

CONCLUSIONS

The finding of MEN1 germ-line mutation in all patients with familial MEN1 syndrome suggests that genetic screening should be useful in our population to identify affected individuals within a kindred and allow early detection of MEN1-related tumours.

Plasma phospholipid transfer protein activity and small, dense LDL in type 2 diabetes mellitus

BACKGROUND

Phospholipid transfer protein (PLTP) and cholesteryl ester transfer protein (CETP) remodel circulating lipoproteins and play a role in the antiatherogenic reverse cholesterol transport pathway. The present study determined whether abnormalities in the LDL subfraction pattern in type 2 diabetic patients were related to changes in lipid transfer proteins.

METHODS

Low-density lipoprotein (LDL) subfractions were measured by density gradient ultracentrifugation and plasma PLTP and CETP activities by radiometric assays in 240 diabetic patients and 136 controls.

RESULTS

The diabetic patients had lower LDL-I (P < 0.001) and higher LDL-III concentrations than the controls (P < 0.001). Plasma PLTP activity was increased (P < 0.001) whereas no significant differences were seen in CETP activity. In the diabetic patients, small, dense LDL-III correlated with plasma triglyceride (r = 0.18, P < 0.01), HDL (r = -0.14, P < 0.05), PLTP (r = 0.29, P < 0.001) and CETP activity (r = 0.15, P < 0.05). Linear regression analysis showed that plasma PLTP activity, triglyceride and age were the major determinants of LDL-III concentration (r2 = 28%, P < 0.001). The univariate relationship between CETP and LDL-III was no longer significant after adjusting for PLTP activity.

CONCLUSIONS

The increase in plasma PLTP activity was independently associated with small, dense LDL concentrations in type 2 diabetes. Hence, elevated PLTP activity might have both antiatherogenic and pro-atherogenic potential in these patients.

Acute effect of orlistat on post-prandial lipaemia and free fatty acids in overweight patients with Type 2 diabetes mellitus

AIMS

Post-prandial lipaemia is prolonged and exaggerated in patients with Type 2 diabetes mellitus, with an accumulation of atherogenic triglyceride-rich lipoprotein remnants. We postulate that orlistat, a gastrointestinal lipase inhibitor, may cause changes in post-prandial lipoprotein metabolism by reducing dietary triglyceride absorption.

METHODS

The acute effect of a single dose of 120 mg orlistat on post-prandial glucose, lipids, remnant lipoproteins and free fatty acids (FFA) was evaluated in a randomized, double-blind, placebo-controlled cross-over study of 63 overweight patients with Type 2 diabetes mellitus (body mass index 30.4 +/- 3.8 kg/m2). Either a single dose of orlistat or placebo was given before a standard mixed meal containing 70 g of fat and plasma triglyceride (TG), remnant-like particles cholesterol (RLP-C) and FFA were sampled at 2-h intervals for 8 h. RLP-C was measured by an immunoseparation assay and FFA by an enzymatic colorimetric method.

RESULTS

The concentrations of plasma TG (P < 0.0001), RLP-C (P = 0.003), and FFA (P < 0.0001) were significantly lower at 2 h after orlistat compared with placebo. Both plasma RLP-C (P = 0.04) and FFA (P < 0.0001) remained lower after orlistat than placebo at 4 h. The incremental area under the curve (iAUC) above baseline fasting level for both TG and RLP-C was significantly more reduced after orlistat than placebo (iAUC-TG 5.8 (3.7-8.2) mmol/l x h-1 vs. 5.7 (4.1-10.9), respectively, P = 0.04; iAUC-RLP-C: 0.53 (0.23-1.04) mmol/l x h-1 vs. 0.56 (0.35-1.40), respectively, P = 0.02). The test meal was well tolerated by all subjects, with only three subjects reporting faecal urgency after orlistat.

CONCLUSIONS

Orlistat has a beneficial effect on post-prandial lipaemia in overweight Type 2 diabetic patients and lowers plasma TG, RLP-C and FFA in the early post-prandial period.

Hyperhomocysteinemia and impaired vasomotor function in type 2 diabetes mellitus

BACKGROUND

Hyperhomocysteinemia has been shown to adversely affect vascular function. The aim of this study was to determine whether hyperhomocysteinemia was independently associated with changes in endothelium-dependent and -independent vasomotor functions in patients with type 2 diabetes mellitus.

MATERIALS AND METHODS

Fasting homocysteine (tHcy) was measured in 123 patients with type 2 diabetes and in 61 nondiabetic controls. Endothelium-dependent and -independent vasodilation was measured using high-resolution vascular ultrasound.

RESULTS

Plasma tHcy concentration was increased in the diabetic patients (11.1 +/- 3.7 micromol L(-1) vs. 9.8 +/- 2.9, P < 0.05). The prevalence of hyperhomocysteinemia (defined as tHcy > 15 micromol L(-1)) was higher in the diabetic patients (P < 0.05). Within group comparisons showed that both the abnormalities in endothelium-dependent and -independent vasodilation were significantly more severe in diabetic patients with tHcy 10-15 (P < 0.05) and tHcy > 15 micromol L(-1) (P < 0.05) than in those patients with tHcy < 10 micromol L(-1). When compared with nondiabetic controls matched for tHcy levels, impairment of endothelium-dependent and -independent vasodilation were already evident, even in patients with normal tHcy levels (P < 0.01). Despite significant univariate relationships between tHcy and endothelium-dependent (r = -0.24, P < 0.01) and -independent vasodilation (r = -0.33, P < 0.01) in patients with diabetes, only the relationship between tHcy and endothelium-independent vasodilation remained significant after adjusting for other cardiovascular risk factors in multiple regression analysis.

CONCLUSIONS

Impairment of endothelium-dependent and -independent vasodilation was already present in diabetic patients with normal tHcy levels, and these abnormalities became more severe with increasing tHcy levels. Only the association between tHcy and endothelium-independent vasodilation was free of other cardiovascular risk factors.

Atorvastatin lowers C-reactive protein and improves endothelium-dependent vasodilation in type 2 diabetes mellitus

Endothelial dysfunction is frequently found in diabetic subjects. This study was performed to investigate whether atorvastatin therapy was able to reverse endothelial dysfunction in type 2 diabetes and, if so, whether the effect was due to its antiinflammatory action. Eighty patients (baseline low density lipoprotein, 4.37 +/- 0.71 mmol/liter) were randomized to atorvastatin (10 mg daily for 3 months, followed by 20 mg daily for 3 months) or placebo in a double blind study. Endothelial function was assessed by high resolution vascular ultrasound, and high sensitivity C-reactive protein (CRP) was assessed by immunoturbidimetric assay. Diabetic patients had higher CRP (P < 0.01) than matched nondiabetic controls, and both endothelium-dependent and independent vasodilation were impaired (P < 0.01). Atorvastatin (10 and 20 mg) lowered plasma cholesterol by 32.9% and 38.0%, triglyceride by 15.4% and 23.1%, and low density lipoprotein by 43.4% and 50.1%, respectively. At 6 months, plasma CRP decreased in the atorvastatin group compared with baseline (P < 0.05). Endothelium-dependent vasodilation improved in the atorvastatin group compared with the placebo group (P < 0.05). The percent change in endothelium-dependent vasodilation at 6 months correlated with the percent change in CRP (r = -0.44; P < 0.05), but not with changes in plasma lipids. In conclusion, treatment with atorvastatin in type 2 diabetes led to a significant improvement in endothelium-dependent vasodilation, which might be partly related to its anti-inflammatory effect.