Apolipoprotein B-48: a unique marker of chylomicron metabolism

Apolipoprotein B-48 (apoB-48) is known to be the only specific marker of intestinal chy lomicron particles. The amino acid sequence of apoB-48 represents 48% of the initial sequence of apoB-100. ApoB-48 is synthesized only by the intestine in humans, while apoB-100 is synthesized primarily by the liver. Therefore, apoB-48 is a most appropriate biomarker for cardiovascular and nutritional investigation of postprandial chylomicron metabolism. In this review article, we discussed the difference between the recent find ings and Zilversmit's proposal of postprandial hyperlipidemia reported over 30 years ago. The characteristics and role of apoB-48 as an apolipoprotein in chylomicrons, especially as a marker of chylomicron remnant lipoproteins, are described. The need for appropriate analytical methods to measure apoB-48 is also discussed.

Apoprotein B, small-dense LDL and impaired HDL remodeling is associated with larger plaque burden and more noncalcified plaque as assessed by coronary CT angiography and intravascular ultrasound with radiofrequency backscatter: results from the ATLANTA I study

Background

Apoprotein B–containing lipoproteins are atherogenic, but atheroprotective functions of apoprotein A–containing high‐density lipoprotein (HDL) particles are poorly understood. The association between lipoproteins and plaque components by coronary computed tomography angiography (CTA) and intravascular ultrasound with radiofrequency backscatter (IVUS/VH) has not been evaluated.

Methods and Results

Quantitative, 3‐dimensional plaque measurements were performed in 60 patients with CTA and IVUS/VH. Apoproteins, lipids, and HDL subpopulations were measured with 2‐dimensional (2D) gel electrophoresis, and correlation was assessed with univariate and multivariable models. ApoB particles were associated with a higher proportion of noncalcified plaque (NCP) and a lower proportion of calcified plaque (small, dense low‐density lipoprotein cholesterol and high‐density NCP: r=0.3, P=0.03; triglycerides and low‐density NCP: r=0.34, P=0.01). Smaller, dense, lipid‐poor HDL particles were associated with a shift from calcified plaque to NCP on CTA (α3‐HDL% and low‐density NCP: r=0.32, P=0.02) and with larger plaque volume on IVUS/VH (α4‐HDL%: r=0.41, P=0.01; α3‐HDL%: r=0.37, P=0.03), because of larger dense calcium (α4‐HDL%: r=0.37, P=0.03), larger fibrous tissue (α4‐HDL%: r=0.34, P=0.04), and larger necrotic core (α4‐HDL%: r=0.46, P<0.01; α3‐HDL%: r=0.37, P=0.03). Larger lipid‐rich HDL particles were associated with less low‐density NCP on CTA (α2‐HDL%: r=−0.34, P=0.02; α1‐HDL%: r=−0.28, P=0.05), with smaller plaque volume on IVUS/VH (pre‐α2‐HDL: r=−0.33, P=0.05; α1‐HDL%: r=−0.41, P=0.01; pre‐α2‐HDL: r=−0.33, P=0.05) and with less necrotic core (α1‐HDL: r=−0.42, P<0.01; pre‐α2‐HDL: r=−0.38, P=0.02; α2‐HDL: r=−0.35, P=0.03; pre‐α1‐HDL: r=−0.34, P=0.04). Pre‐β2‐HDL was associated with less calcification and less stenosis by both modalities.

Conclusions

ApoB and small HDL particles are associated with larger plaque burden and more noncalcified plaque, whereas larger HDL and pre‐β2‐HDL particles are associated with plaque burden and less noncalcified plaque by both CTA and IVUS/VH.

Plasma adiponectin is a more specific marker of fatty liver than a marker of metabolic syndrome in Japanese men

BACKGROUND

The association of plasma cardiovascular risk markers and metabolic syndrome (MetS) with non-alcoholic fatty liver disease (NAFLD) has not been well defined.

METHODS

Japanese men (n = 809) had standard anthropometric measurements done, and had their liver fat quantitated by ultrasound. Three groups were identified: (1) normal controls without significant disease, (2) preliminary-metabolic syndrome (pre-MetS) cases and (3) MetS cases. Plasma adiponectin, high sensitivity-C reactive protein (hs-CRP), HOMA-IR, lipids, lipoproteins and liver enzymes were evaluated among the three groups.

RESULTS

The prevalence of fatty liver was 13% in controls, 39% in pre-MetS and 62% in MetS. Plasma adiponectin and high density lipoprotein cholesterol (HDL-C) were significantly decreased, and HOMA-IR, hs-CRP, TG, remnant lipoproteins (RLPs) and small dense-LDL-C (sd LDL-C) were significantly increased in subjects with fatty liver compared to those without fatty liver. Multivariate analyses of serum parameters associated with fatty liver revealed that adiponectin and hs-CRP were more strongly associated with the presence of fatty liver than waist circumference. However, HOMA-IR, HDL-C, TG, RLP-C, RLP-TG and sd LDL-C were more strongly associated with waist circumference than with fatty liver. Factor analysis revealed that adiponectin and HDL-C were linked to liver enzymes, lipoproteins and HOMA-IR associated with fatty liver, but not with waist circumference.

CONCLUSIONS

Adiponectin was found to be a more specific diagnostic marker for the presence of fatty liver regardless of MetS status, and was inversely correlated with liver enzyme concentrations. However, RLPs were found to be more specifically associated with the presence of MetS.

Mesoaxial polydactyly is a major feature in Bardet-Biedl syndrome patients with LZTFL1 (BBS17) mutations

Ciliopathies are heterogeneous disorders sharing different clinical signs due to a defect at the level of the primary cilia/centrosome complex. Postaxial polydactyly is frequently reported in ciliopathies, especially in Bardet-Biedl syndrome (BBS). Clinical features and genetic results observed in a pair of dizygotic twins with BBS are reported. The following manifestations were present: retinitis pigmentosa, bilateral insertional polydactyly, cognitive impairment and renal dysfunction. X-rays of the hands confirmed the presence of a 4th mesoaxial extra-digit with Y-shaped metacarpal bones. The sequencing of LZTFL1 identified a missense mutation (NM_020347.2: p.Leu87Pro; c.260T>C) and a nonsense mutation (p.Glu260*; c.778G>T), establishing a compound heterozygous status for the twins. A major decrease of LZTFL1 transcript and protein was observed in the patient's fibroblasts. This is the second report of LZTFL1 mutations in BBS patients confirming LZTFL1 as a BBS gene. Interestingly, the only two families reported in literature thus far with LZTFL1 mutations have in common mesoaxial polydactyly, a very uncommon feature for BBS. This special subtype of polydactyly in BBS patients is easily identified on clinical examination and prompts for priority sequencing of LZTFL1 (BBS17).

Mutations in SDCCAG8/NPHP10 Cause Bardet-Biedl Syndrome and Are Associated with Penetrant Renal Disease and Absent Polydactyly

The ciliopathies are an expanding group of disorders caused by mutations in genes implicated in the biogenesis and function of primary cilia. Bardet-Biedl syndrome (BBS) is a model ciliopathy characterized by progressive retinal degeneration, obesity, polydactyly, cognitive impairment, kidney anomalies and hypogonadism. Mutations in SDCCAG8(NPHP10) were described recently in patients with nephronophthisis and retinal degeneration (Senior-Loken syndrome; SLS). Given the phenotypic and genetic overlap between known ciliopathy genes, we hypothesized that mutations in SDCCAG8 might also contribute alleles to more severe, multisystemic ciliopathies. We performed genetic and phenotypic analyses of 2 independent BBS cohorts. Subsequent to mutation screening, we made a detailed phenotypic analysis of 5 families mutated for SDCCAG8 (3 homozygous and 2 compound heterozygous mutations) and conducted statistical analyses across both cohorts to examine possible phenotype-genotype correlations with mutations at this locus. All patients with mutations in SDCCAG8 fulfilled the diagnostic criteria for BBS (retinal degeneration, obesity, cognitive defects, renal failure, hypogonadism). Interestingly, none of the patients with primary SDCCAG8 mutations had polydactyly, a frequent but not obligatory BBS feature. In contrast, the same patients displayed early-onset renal failure, obesity, as well as recurrent pulmonary and ENT infections. Comparison of the phenotypes of these families with our entire BBS cohort indicated that renal impairment and absent polydactyly correlated significantly with causal SDCCAG8 mutations. Thus, SDCCAG8 mutations are sufficient to cause BBS in 1-2% of our combined cohorts, and define this gene as the sixteenth BBS locus (BBS16). The absence of polydactyly and the concomitant, apparently fully penetrant association with early kidney failure represents the first significant genotype-phenotype correlation in BBS that potentially represents an indicator for phenotype-driven priority screening and informs specific patient management.

Confirmation of the role of diabetes in the local recurrence of surgically resected non-small cell lung cancer

PURPOSE

We recently demonstrated that diabetes mellitus was an independent risk factor for local recurrence (LR) for patients undergoing resection of non-small cell lung cancer (NSCLC). This investigation was performed to confirm or refute this finding in a different patient cohort.

MATERIALS AND METHODS

Patients were eligible if they did not have a second primary cancer within 5 years of the original diagnosis, had at least 3-month follow-up, and did not receive radiotherapy. There were 373 and 168 patients in the original (P1) and confirmatory (P2) cohorts, respectively, with 66 and 30 patients with diabetes.

RESULTS

The median follow-up was 33 months (range, 3-98 months). Diabetes was an independent risk factor for LR in a Cox model in both the P2 (p=0.05, hazard ratio [HR] 2.15) and P1 (p=0.008, HR 1.90) cohorts, separately from BMI, glucose control, and the presence of the metabolic syndrome. The rates of LR in the patients with diabetes after combining the cohorts at 2, 3, and 5 years were 23%, 33%, and 56%, respectively; these rates were 15%, 19%, and 26% in non-diabetics. In multivariate Cox regression and competing risk analysis of the combined cohorts, the HRs for LR in patients with diabetes exceeded those of more established risk factors for LR including a 1-cm increase in tumor size and lymphovascular invasion.

CONCLUSIONS

Diabetes was confirmed to be an independent predictor of the risk of LR following resection of NSCLC.

Development and improvement of a serum-free suspension process for the production of recombinant adenoviral vectors using HEK293 cells

Human Embryonic Kidney 293 (HEK293) cells were adapted into a serum-free suspension medium through steps of gradual serum weaning for the production of adenoviral (AdV) gene therapy vectors. The presence of sodium heparin in the medium formulation reduced cell clumping dramatically in suspension culture. The adapted cells were ready to grow either in serum-containing medium as an attached culture or in serum-free medium in suspension culture. A scalable production process was developed in shake flasks and was then evaluated in stirred tank bioreactors. This process includes a growth phase in batch-mode followed by a production phase involving medium perfusion and supplementation. Fortification with calcium chloride post viral inoculation resulted in an increase in virus production by at least one fold. Addition of stimulating agents such as sodium butyrate, N-acetyl-L-cysteine (NAC), dimethyl sulfoxide(DMSO), or ethyl alcohol post infection was shown to further improve virus production in a dose-dependent manner. The serum-free suspension process described here should be suitable for the manufacturing of other E1-deleted AdV vectors and could potentially be used for the production of recombinant proteins by HEK293 cells.

Bayesian methods for meta-analysis of causal relationships estimated using genetic instrumental variables

Genetic markers can be used as instrumental variables, in an analogous way to randomization in a clinical trial, to estimate the causal relationship between a phenotype and an outcome variable. Our purpose is to extend the existing methods for such Mendelian randomization studies to the context of multiple genetic markers measured in multiple studies, based on the analysis of individual participant data. First, for a single genetic marker in one study, we show that the usual ratio of coefficients approach can be reformulated as a regression with heterogeneous error in the explanatory variable. This can be implemented using a Bayesian approach, which is next extended to include multiple genetic markers. We then propose a hierarchical model for undertaking a meta-analysis of multiple studies, in which it is not necessary that the same genetic markers are measured in each study. This provides an overall estimate of the causal relationship between the phenotype and the outcome, and an assessment of its heterogeneity across studies. As an example, we estimate the causal relationship of blood concentrations of C-reactive protein on fibrinogen levels using data from 11 studies. These methods provide a flexible framework for efficient estimation of causal relationships derived from multiple studies. Issues discussed include weak instrument bias, analysis of binary outcome data such as disease risk, missing genetic data, and the use of haplotypes.

Drug treatment of chronic-intermittent abdominal cramping and pain: a multi-national survey on usage and attitudes

BACKGROUND

Data on drug treatment of abdominal cramping and pain are sparse.

AIM

To compare treatment of abdominal cramping and pain across countries worldwide.

METHODS

A multi-national survey was conducted in the USA, Mexico, Brazil, Argentina, Germany, Belgium, Italy and the UK. In each country, approximately 210 people were interviewed on various aspects of drug treatment of their complaints.

RESULTS

In total, 1717 participants were interviewed. Respondents from the Americas used more medication (approximately 90%) than those from Europe (approximately 70%). Over-the-counter remedies were much more used than prescription drugs (except for Mexico). Medication was mainly taken on demand to relieve a pain episode. In the Latin American countries, antispasmodics were most popular (up to 73%), in Germany antacids, and in the UK antacids and analgesics. Regarding expectations of treatment, 'fast onset of action' ranked the highest, followed by 'highly effective' and 'well tolerated'.

CONCLUSIONS

A majority of people afflicted by abdominal cramping and pain use medication and take them on demand. Consequently, rapid onset of action is mentioned as most important. Antispasmodics are the class most frequently used with considerable variation from country to country.

Unraveling the directional link between adiposity and inflammation: a bidirectional Mendelian randomization approach

CONTEXT

Associations between adiposity and circulating inflammation markers are assumed to be causal, although the direction of the relationship has not been proven.

OBJECTIVE

The aim of the study was to explore the causal direction of the relationship between adiposity and inflammation using a bidirectional Mendelian randomization approach.

METHODS

In the PROSPER study of 5804 elderly patients, we related C-reactive protein (CRP) single nucleotide polymorphisms (SNPs) (rs1800947 and rs1205) and adiposity SNPs (FTO and MC4R) to body mass index (BMI) as well as circulating levels of CRP and leptin. We gave each individual two allele scores ranging from zero to 4, counting each pair of alleles related to CRP levels or BMI.

RESULTS

With increasing CRP allele score, there was a stepwise decrease in CRP levels (P for trend < 0.0001) and a 1.98 mg/liter difference between extremes of the allele score distribution, but there was no associated change in BMI or leptin levels (P >or= 0.89). By contrast, adiposity allele score was associated with 1) an increase in BMI (1.2 kg/m(2) difference between extremes; P for trend 0.002); 2) an increase in circulating leptin (5.77 ng/ml difference between extremes; P for trend 0.0027); and 3) increased CRP levels (1.24 mg/liter difference between extremes; P for trend 0.002).

CONCLUSIONS

Greater adiposity conferred by FTO and MC4R SNPs led to higher CRP levels, with no evidence for any reverse pathway. Future studies should extend our findings to other circulating inflammatory parameters. This study illustrates the potential power of Mendelian randomization to dissect directions of causality between intercorrelated metabolic factors.

New perspectives on community-acquired pneumonia in 388 406 patients. Results from a nationwide mandatory performance measurement programme in healthcare quality

BACKGROUND

The database of the German programme for quality in healthcare including data of every hospitalised patient with community-acquired pneumonia (CAP) during a 2-year period (n = 388 406 patients in 2005 and 2006) was analysed.

METHODS

End points of the analysis were: (1) incidence; (2) outcome; (3) performance of the CRB-65 (C, mental confusion; R, respiratory rate >or=30/min; B, systolic blood pressure <90 mm Hg or diastolic blood pressure or=65 years) score in predicting death; and (4) lack of ventilatory support as a possible indicator of treatment restrictions. The CRB-65 score was calculated, resulting in three risk classes (RCs).

RESULTS

The incidence of hospitalised CAP was 2.75 and 2.96 per 1000 inhabitants/year in 2005 and 2006, respectively, higher for males (3.21 vs 2.52), and strongly age related, with an incidence of 7.65 per 1000 inhabitants/year in patients aged >or=60 years over 2 years. Mortality (13.72% and 14.44%) was higher than reported in previous studies. The CRB-65 RCs accurately predicted death in a three-class pattern (mortality 2.40% in CRB-65 RC 1, 13.43% in CRB-65 RC 2 and 34.39% in CRB-65 RC 3). The first days after admission were consistently associated with the highest risk of death throughout all risk classes. Only a minority of patients who died had received mechanical ventilation during hospitalisation (15.74%).

CONCLUSIONS

Hospitalised CAP basically is a condition of the elderly associated with a higher mortality than previously reported. It bears a considerable risk of early mortality, even in low risk patients. CRB-65 is a simple and powerful tool for the assessment of CAP severity. Hospitalised CAP is a frequent terminal event in chronic debilitated patients, and a limitation of treatment escalation is frequently applied.