Adverse systemic arterial function in patients with selenium deficiency

BACKGROUND

Experimental studies have shown that selenium is involved in the synthesis of selenoproteins which might contribute to cardiovascular protection. However, the relationship between selenium deficiency and vascular function in clinical context remains unknown.

OBJECTIVE

To investigate for any relationship between selenium deficiency and systemic arterial function in patients with high risk of vascular events.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

306 consecutive patients with high risk for cardiovascular events (coronary artery disease 35%, acute/ recurrent ischemic stroke 40%, diabetes mellitus 54%) followed up at internal medicine outpatient clinics.

MEASUREMENTS

Non-invasive brachial-ankle pulse wave velocity (PWV) was determined using vascular profiling system (VP-2000). Long-term intake of selenium was determined by a validated food frequency questionnaire.

RESULTS

Mean daily selenium intake was 59.5 ± 52.1 mcg/day, and mean PWV was 1782.4 ± 418.4 cm/s. Patients with selenium intake <10th percentile had significantly higher PWV as compared to patients with intake ≥ 10th percentile (1968.2 ± 648.9 cm/s versus 1762.2 ± 381.6 cm/s, P=0.010). After adjusting for potential confounders including age, gender, history of hypertension, hyperlipidemia, diabetes and cardiovascular disease, smoking status, use of cardiovascular medications, waist-hip ratio, education/ financial status, physical activity, calorie intake and intake of antioxidant vitamins, deficient selenium intake <10th percentile remained independently predictive of increased PWV by +363.4 cm/s [95% CI: 68.1 to 658.6, P=0.016, relative increase 21%].

CONCLUSIONS

Selenium deficiency is associated with adverse arterial function in patients with high risk for vascular events.

Increased arterial stiffness in patients with psoriasis is associated with active systemic inflammation

BACKGROUND

Psoriasis is associated with premature atherosclerosis although the underlying mechanism remains unclear.

OBJECTIVES

We sought to investigate the relationship between disease activity and systemic inflammation in patients with psoriasis, and macrovascular and microvascular function.

METHODS

Fifty-two patients with psoriasis (mean ± SD age 44 ± 8 years; 38 men) were compared with 50 age- and sex-matched controls. Baseline demographics and high-sensitivity C-reactive protein (hs-CRP) level were recorded for each subject. Psoriatic disease activity was assessed using the Psoriasis Area and Severity Index (PASI). Arterial stiffness and endothelial function were assessed using brachial to ankle pulse wave velocity (baPWV) and digital hyperaemic response measured using the peripheral arterial tonometry (PAT) index.

RESULTS

Patients with psoriasis had significantly higher hs-CRP (mean ± SD 5·3 ± 5·1 vs. 1·9 ± 1·6 mg L(-1), P < 0·01) and baPWV (mean ± SD 14·5 ± 2·5 vs. 13·2 ± 1·6 m s(-1) , P < 0·01) but not PAT index (mean ± SD 2·06 ± 0·59 vs. 2·10 ± 0·44, P = 0·70) than controls. There was significant correlation of hs-CRP with baPWV (r = 0·51, P < 0·01) and with PASI (r = 0·48, P < 0·01). Multiple linear regression analysis demonstrated that baPWV is independently correlated with age, fasting glucose and hs-CRP (P < 0·05), but does not predict PAT index. Each mg L(-1) increase in hs-CRP accounted for an increase in baPWV of +0·12 m s(-1) (95% confidence interval 0·01-0·22, P = 0·03).

CONCLUSIONS

Young patients with psoriasis have increased arterial stiffness but not microvascular dysfunction compared with healthy controls. More importantly, hs-CRP positively correlated with, and independently predicted, arterial stiffness. This suggests that systemic inflammation in patients with psoriasis is associated with premature atherosclerosis.

Isobaric labeling and tandem mass spectrometry: a novel approach for profiling and quantifying proteins differentially expressed in amniotic fluid in preterm labor with and without intra-amniotic infection/inflammation

OBJECTIVE

Examination of the amniotic fluid (AF) proteome has been previously attempted to identify useful biomarkers in predicting the outcome of preterm labor (PTL). Isobaric Tag for Relative and Absolute Quantitation (iTRAQ) labeling allows direct ratiometric comparison of relative abundance of identified protein species among multiplexed samples. The purpose of this study was to apply, for the first time, the combination of iTRAQ and tandem mass spectrometry to identify proteins differentially regulated in AF samples of women with spontaneous PTL and intact membranes with and without intra-amniotic infection/inflammation (IAI).

METHODS

A cross-sectional study was designed and included AF samples from patients with spontaneous PTL and intact membranes in the following groups: (1) patients without IAI who delivered at term (n = 26); (2) patients who delivered preterm without IAI (n = 25); and (3) patients with IAI (n = 24). Proteomic profiling of AF samples was performed using a workflow involving tryptic digestion, iTRAQ labeling and multiplexing, strong cation exchange fractionation, and liquid chromatography tandem mass spectrometry. Twenty-five separate 4-plex samples were prepared and analyzed.

RESULTS

Collectively, 123,011 MS(2) spectra were analyzed, and over 25,000 peptides were analyzed by database search (X!Tandem and Mascot), resulting in the identification of 309 unique high-confidence proteins. Analysis of differentially present iTRAQ reporter peaks revealed many proteins that have been previously reported to be associated with preterm delivery with IAI. Importantly, many novel proteins were found to be up-regulated in the AF of patients with PTL and IAI including leukocyte elastase precursor, Thymosin-like 3, and 14-3-3 protein isoforms. Moreover, we observed differential expression of proteins in AF of patients who delivered preterm in the absence of IAI in comparison with those with PTL who delivered at term including Mimecan precursor, latent-transforming growth factor beta-binding protein isoform 1L precursor, and Resistin. These findings have been confirmed for Resistin in an independent cohort of samples using ELISA. Gene ontology enrichment analysis was employed to reveal families of proteins participating in distinct biological processes. We identified enrichment for host defense, anti-apoptosis, metabolism/catabolism and cell and protein mobility, localization and targeting.

CONCLUSIONS

(1) Proteomics with iTRAQ labeling is a profiling tool capable of revealing differential expression of proteins in AF; (2) We discovered 82 proteins differentially expressed in three clinical subgroups of premature labor, 67 which were heretofore unknown. Of particular importance is the identification of proteins differentially expressed in AF from women who delivered preterm in the absence of IAI. This is the first report of the positive identification of biomarkers in this subgroup of patients.

Biochemical and molecular characterization of tyrosine hydroxylase deficiency in Hong Kong Chinese

Tyrosine hydroxylase deficiency is a rare neurotransmitter disorder affecting the rate-limiting step in catecholamine biosynthesis. There are about 40 cases reported worldwide. Here, we report the biochemical and molecular findings of eight unrelated Chinese patients with tyrosine hydroxylase deficiency. We have identified eight novel mutations with 5 missense, 2 nonsense and 1 splicing mutations in the TH gene, namely p.R153X, p.R169X, p.G294R, p.G315S, p.A385V, p.I394T, p.G408R, and c.1163+5G>C. The mutations of the TH gene in Chinese are heterogeneous.

Fish-oil supplement has neutral effects on vascular and metabolic function but improves renal function in patients with Type 2 diabetes mellitus

AIMS

Increased dietary fish-oil consumption is associated with a reduced risk of coronary heart events and has pronounced effects on dyslipidaemia. However, the effects of fish-oil supplement on vascular function and metabolic profile in patients with Type 2 diabetes mellitus (DM) are unclear.

METHODS

In a double-blind placebo-controlled trial, we randomized 97 Type 2 DM patients without prior cardiovascular disease to fish-oil (4 g/day, n = 49) or olive-oil (with equivalent calories, as placebo, n = 48) supplements for 12 weeks. Assessment of vascular function with brachial artery flow-mediated dilation (FMD) and circulating levels of endothelial progenitor cells (EPCs), and metabolic parameters, high-sensitivity C-reactive protein (hsCRP), oxidative stress markers and renal function were examined before and after the supplement.

RESULTS

Despite a significant reduction in serum triglycerides (-0.47 mmol/l, P < 0.01), 12-week supplement of fish oil did not improve vascular function as determined by FMD (+0.16%, P = 0.83) and circulating EPC count (+4 cells/microl, P = 0.78). Furthermore, fish-oil supplement did not have any significant treatment effects on hsCRP, oxidative stress, low- and high-density lipoprotein and glycated haemoglobin (HbA(1c)) (all P > 0.05). In contrast, serum creatinine was lower (-4.5 micromol/l, P = 0.01) in fish-oil-treated patients as compared with control subjects.

CONCLUSIONS

This study demonstrated that 12 weeks of fish-oil supplement had no significant beneficial effect on vascular endothelial function, but improved renal function without changes in endothelial function, metabolic profiles, blood pressure, inflammation or oxidative stress in patients with Type 2 DM.

A randomised controlled trial of nasal continuous positive airway pressure on insulin sensitivity in obstructive sleep apnoea

The effects of treatment of obstructive sleep apnoea (OSA) on glucose metabolism have been investigated previously with conflicting results. This study evaluated the impact of nasal continuous positive airway pressure (nCPAP) treatment of OSA on insulin sensitivity. Males with moderate/severe OSA and no significant comorbidity were randomised to a therapeutic or sham nCPAP treatment group for 1 week and then reassessed. Those who received therapeutic nCPAP were further evaluated at 12 weeks. Insulin sensitivity (K(itt)) was estimated by the short insulin tolerance test. Other evaluations included blood pressure, metabolic profile, urinary catecholamines and intra-abdominal fat. In total, 61 Chinese subjects were randomised. 31 subjects receiving therapeutic nCPAP showed an increase in K(itt) (6.6+/-2.9 to 7.6+/-3.2 % x min(-1); p = 0.017), while the 30 patients on sham CPAP had no significant change, and the changes in K(itt) were different between the two groups (p = 0.022). At 12 weeks, improvement in K(itt) was seen in 20 subjects with BMI >or=25 kg x m(-2) (median (interquartile range) 28.3 (26.6-31.5); p = 0.044), but not in the nine subjects with BMI<25 kg x m(-2), or the entire group. The findings indicate that therapeutic nCPAP treatment of OSA for 1 week improved insulin sensitivity in nondiabetic males, and the improvement appeared to be maintained after 12 weeks of treatment in those with moderate obesity.

Iron supplement in pregnancy and development of gestational diabetes--a randomised placebo-controlled trial

OBJECTIVE

To test the hypothesis that iron supplement from early pregnancy would increase the risk of gestational diabetes mellitus (GDM).

DESIGN

Randomised placebo-controlled trial.

SETTING

A university teaching hospital in Hong Kong.

POPULATION

One thousand one hundred sixty-four women with singleton pregnancy at less than 16 weeks of gestation with haemoglobin (Hb) level between 8 and 14 g/dl and no pre-existing diabetes or haemoglobinopathies.

METHODS

Women were randomly allocated to receive 60 mg of iron supplement daily (n= 565) or placebo (n= 599). Oral glucose tolerance tests (OGTTs) were performed at 28 and 36 weeks. Women were followed up until delivery.

OUTCOME MEASURES

The primary outcome was development of GDM at 28 weeks. The secondary outcomes were 2-hour post-OGTT glucose levels, development of GDM at 36 weeks and delivery and infant outcomes.

RESULTS

There was no significant difference in the incidence of GDM in the iron supplement and placebo groups at 28 weeks (OR: 1.04, 95% confidence interval [CI]: 0.7-1.53 at 90% power) or 36 weeks. Maternal Hb and ferritin levels were higher in the iron supplement group at delivery (P < 0.001 and P= 0.003, respectively). Elective caesarean section rate was lower in the iron supplement group (OR: 0.58, 95% CI: 0.37-0.89). Infant birthweight was heavier (P= 0.001), and there were fewer small-for-gestational-age babies in the iron supplement group (OR: 0.46, 95% CI: 0.24-0.85).

CONCLUSION

Iron supplement from early pregnancy does not increase the risk of GDM. It may have benefits in terms of pregnancy outcomes.

Prodrug delivery of novel PTP1B inhibitors to enhance insulin signalling

A growing percentage of the population is resistant to two key hormones - insulin and leptin - as a result of increased obesity, often leading to significant health consequences such as type 2 diabetes. Protein tyrosine phosphatase 1B (PTP1B) is a key negative regulator of signalling by both of these hormones, so that inhibitors of this enzyme may provide promise for correcting endocrine abnormalities in both diabetes and obesity. As with other tyrosine phosphatases, identification of viable drug candidates targeting PTP1B has been elusive because of the nature of its active site. Beginning with novel phosphotyrosine mimetics, we have designed some of the most potent PTP1B inhibitors. However, their highly acidic structures limit intrinsic permeability and pharmacokinetics. Ester prodrugs of these inhibitors improve their drug-like properties with the goal of delivering these nanomolar inhibitors to the cytoplasm of cells within target tissues. In addition to identifying prodrugs that is able to deliver active drugs into cells to inhibit PTP1B and increase insulin signalling, these compounds were further modified to gain a variety of cleavage properties for targeting activity in vivo. One such prodrug candidate improved insulin sensitivity in ob/ob mice, with lowered fasting blood glucose levels seen in the context of lowered fasting insulin levels following 4 days of intraperitoneal dosing. The results presented in this study highlight the potential for design of orally active drug candidates targeting PTP1B, while also delineating the considerable challenges remaining.

Organ-specific hemosiderosis and functional correlation in Chinese patients with thalassemia intermedia and hemoglobin H disease

We performed MRI assessment in 37 adult Chinese patients with thalassemia intermedia and hemoglobin H disease. Despite abnormal ferritin and liver T2*, only 5% of patients had cardiac hemosiderosis. The two patients with reduced ejection fraction had normal cardiac T2*. Half of the cases showed pituitary and pancreatic iron loading. Subclinical endocrine abnormalities (HOMA, insulin growth factor) showed correlation with pancreatic, pituitary, and cardiac MRI values. Prospective data with serial functional and imaging monitoring is needed to verify the utility for chelation to improve cardiac and endocrine function in this group of patients.

One-stop measurement of iron deposition in the anterior pituitary, liver, and heart in thalassemia patients

PURPOSE

To assess the feasibility of one-stop evaluation of iron load of myocardium, liver, and anterior pituitary gland in thalassemia patients.

MATERIALS AND METHODS

Fifty thalassemia major patients underwent a breath-hold magnetic resonance imaging (MRI) sequence for assessment of T2* for liver and myocardium, a short axis cine trueFISP sequence covering base to apex to assess the ejection fraction of left ventricle, and a turbo spin echo T2-weighted sequence for the anterior pituitary gland. The MRI parameters were correlated with serum growth hormone, insulin growth factor-1 (IGF-1), insulin growth factor binding protein-3 (IGFBP-3), and endocrine failure.

RESULTS

Ferritin was found to be associated with T2* liver (P < 0.005), T2SI (signal intensity) pituitary (P = 0.001), and T2 pituitary/fat (P = 0.001), but not with T2* heart. There was significant correlation of T2SI pituitary with IGF-1 and IGFBP-3. T2* liver (P < 0.001), T2* heart (P < 0.001), pituitary SI (P < 0.001) and pituitary/fat SI (P = 0.002) were also found to be significantly correlated with a history of hypogonadism. T2* heart was also found to be significantly correlated with IGF-1.

CONCLUSION

A quick MRI protocol for assessment of T2* liver, T2* heart, and T2SI pituitary is technically feasible. This might form an objective basis to monitor the response to different organs to chelation therapy.

Rapamycin prevents the development of nephritis in lupus-prone NZB/W F1 mice

Rapamycin is a potent immunosuppressive drug currently used mainly for rejection prophylaxis in renal transplantation. The aim of this study was to determine the effect of rapamycin treatment on the development of nephritis in lupus-prone New Zealand Black/White F1 (NZB/W F1) mice. Twelve-week-old female NZB/W F1 mice were treated with rapamycin (3 mg/kg body weight) or saline once daily by oral gavage for 20 weeks. The severity of nephritis was assessed by clinical and biochemical parameters, renal histology, immunohistochemistry and gene expression studies. Rapamycin treatment markedly reduced proteinuria, improved renal function, decreased serum anti-double stranded DNA antibody levels and diminished splenomegaly. Kidney sections from saline-treated mice showed marked mesangial proliferation, tubular dilation with protein cast deposition and interstitial inflammatory cell infiltration. Rapamycin-treated mice had near normal renal histology, with marked reduction in glomerular immune deposition and the infiltration by T cells, B cells and macrophages. Rapamycin treatment was associated with down-regulation of intra-renal expression of monocyte chemoattractant protein-1 (MCP-1) mRNA and protein. We conclude that rapamycin is highly effective in preventing the development of nephritis in NZB/W F1 mice. The beneficial effects of rapamycin are mediated through inhibition of lymphoproliferation and reduced MCP-1 expression.

A magnetic resonance imaging study of iron overload in hemopoietic stem cell transplant recipients with increased ferritin levels

We performed a study of magnetic resonance imaging (MRI) assessment of hemosiderosis in the heart (T2/T2*), liver (T2*), pancreas (T2*), and pituitary gland (T2/T2*/SIR) in 20 hemopoietic stem cell transplant (HSCT) recipients (median peak ferritin levels 7615 pmol/L, range 3411 to 33000 pmol/L). MRI reading was abnormal in the heart (5%), liver (85%), pancreas (40%), and pituitary gland (55%). The heart T2 correlated with peak ferritin levels (P=.024), while the liver T2* correlated with current ferritin (P=.038) values only. Pancreatic T2* values correlated with pituitary T2 and signal intensity ratio values. The ejection fraction was abnormal in 10% of cases and did not correlate with ferritin level or heart T2. The peak liver enzymes correlated with peak ferritin (P=.025), but the current liver enzymes were mostly normal. Pancreatic assessments (fasting glucose, insulin, beta cell function, insulin reserve, and C-peptide) and pituitary growth hormone axis assessments (growth hormone, insulin growth factor-1, and insulin growth factor binding protein-3) were abnormal in 40% to 70% of cases. They were unrelated to pancreas or pituitary MRI values. Interestingly, endocrine assessments correlated with heart T2 values and peak (but not current) ferritin levels. We concluded that iron overload may contribute to organ damage after HSCT, and MRI assessment may be useful in its detection and treatment monitoring.

Complete recovery from acute encephalopathy of late-onset ornithine transcarbamylase deficiency in a 3-year-old boy

Ornithine transcarbamylase deficiency is the commonest urea cycle disorder which is transmitted in X-linked inheritance. It is mainly characterized in males by acute encephalopathy and hyperammonaemia with fatal outcomes in both classical neonatal and late-onset types. We report a 3-year-old healthy Hong Kong Chinese boy who presented with acute encephalopathy and coma after three days of gastroenteritis. He had no focal neurological deficit and brain CT imaging was normal. His plasma ammonia (54 micromol/L) and glutamine (747 micromol/L) concentrations were normal. The only biochemical abnormalities detected were marked orotic aciduria (700 micromol/mmol creatinine) and elevated urinary uracil. He regained consciousness spontaneously after three days under intensive care with parenteral fluid therapy. He recovered completely without any neurological deficits. Five months after discharge, urinary uracil concentration remained elevated despite normalized orotic acid concentration. Finally, ornithine transcarbamylase deficiency was diagnosed by DNA analysis. A missense mutation of arginine-to-glutamine substitution on amino acid 277 (p.R277Q) was revealed to be a late-onset mutant. Our case strengthens the argument that in any child with coma or acute encephalopathy of undetermined cause, genetic analysis of the OTC gene and the measurement of urinary uracil concentration remain the most reliable indicators of late-onset OTCD during acute and even quiescent phases. Existing neonatal screening programmes for inheritable metabolic disorders fail to detect late-onset variants. Therefore, a high clinical suspicion is a key to correct and timely diagnosis, especially in those patients with atypical presentations.