Elongation of very long-chain fatty acids is enhanced in X-linked adrenoleukodystrophy

X-linked adrenoleukodystrophy (X-ALD) is a progressive neurodegenerative disorder characterized by the accumulation of saturated and mono-unsaturated very long-chain fatty acids (VLCFA) and reduced peroxisomal VLCFA beta-oxidation activity. In this study, we investigated the role of VLCFA biosynthesis in X-ALD fibroblasts. Our data demonstrate that elongation of both saturated and mono-unsaturated VLCFAs is enhanced in fibroblasts from patients with peroxisomal beta-oxidation defects including X-ALD, and peroxisome biogenesis disorders. These data indicate that enhanced VLCFA elongation is a general phenomenon associated with an impairment in peroxisomal beta-oxidation, and not specific for X-ALD alone. Analysis of plasma samples from patients with X-ALD and different peroxisomal beta-oxidation deficiencies revealed increased concentrations of VLCFAs up to 32 carbons. We infer that enhanced elongation does not result from impaired peroxisomal beta-oxidation alone, but is due to the additional effect of unchecked chain elongation. We demonstrate that elongated VLCFAs are incorporated into complex lipids. The role of chain elongation was also studied retrospectively in samples from patients with X-ALD previously treated with "Lorenzo's oil." We found that the decrease in plasma C26:0 previously found is offset by the increase of mono-unsaturated VLCFAs, not measured previously during the trial. We conclude that evaluation of treatment protocols for disorders of peroxisomal beta-oxidation making use of plasma samples should include the measurement of saturated and unsaturated VLCFAs of chain lengths above 26 carbon atoms. We also conclude that chain elongation offers an interesting target to be studied as a possible mode of treatment for X-ALD and other peroxisomal beta-oxidation disorders.     

The Minimum Clinically Important Difference of the Patient-rated Wrist Evaluation Score for Patients With Distal Radius Fractures

Background

The Patient-rated Wrist Evaluation (PRWE) is a commonly used instrument in upper extremity surgery and in research. However, to recognize a treatment effect expressed as a change in PRWE, it is important to be aware of the minimum clinically important difference (MCID) and the minimum detectable change (MDC). The MCID of an outcome tool like the PRWE is defined as the smallest change in a score that is likely to be appreciated by a patient as an important change, while the MDC is defined as the smallest amount of change that can be detected by an outcome measure. A numerical change in score that is less than the MCID, even when statistically significant, does not represent a true clinically relevant change. To our knowledge, the MCID and MDC of the PRWE have not been determined in patients with distal radius fractures.

Questions/Purposes

We asked: (1) What is the MCID of the PRWE score for patients with distal radius fractures? (2) What is the MDC of the PRWE?

Methods

Our prospective cohort study included 102 patients with a distal radius fracture and a median age of 59 years (interquartile range [IQR], 48–66 years). All patients completed the PRWE questionnaire during each of two separate visits. At the second visit, patients were asked to indicate the degree of clinical change they appreciated since the previous visit. Accordingly, patients were categorized in two groups: (1) minimally improved or (2) no change. The groups were used to anchor the changes observed in the PRWE score to patients’ perspectives of what was clinically important. We determined the MCID using an anchor-based receiver operator characteristic method. In this context, the change in the PRWE score was considered a diagnostic test, and the anchor (minimally improved or no change as noted by the patients from visit to visit) was the gold standard. The optimal receiver operator characteristic cutoff point calculated with the Youden index reflected the value of the MCID.

Results

In our study, the MCID of the PRWE was 11.5 points. The area under the curve was 0.54 (95% CI, 0.37–0.70) for the pain subscale and 0.71 (95% CI, 0.57−0.85) for the function subscale. We determined the MDC to be 11.0 points.

Conclusions

We determined the MCID of the PRWE score for patients with distal radius fractures using the anchor-based approach and verified that the MDC of the PRWE was sufficiently small to detect our MCID.

Clinical Relevance

We recommend using an improvement on the PRWE of more than 11.5 points as the smallest clinically relevant difference when evaluating the effects of treatments and when performing sample-size calculations on studies of distal radius fractures.     

Bezafibrate lowers very long-chain fatty acids in X-linked adrenoleukodystrophy fibroblasts by inhibiting fatty acid elongation

X-linked adrenoleukodystrophy (X-ALD) is caused by mutations in the ABCD1 gene encoding ALDP, an ATP-binding-cassette (ABC) transporter located in the peroxisomal membrane. ALDP deficiency results in impaired peroxisomal β-oxidation and the subsequent accumulation of very long-chain fatty acids (VLCFA; > C22:0) in plasma and tissues. VLCFA are primarily derived from endogenous synthesis by ELOVL1. Therefore inhibiting this enzyme might constitute a feasible therapeutic approach. In this paper we demonstrate that bezafibrate, a PPAR pan agonist used for the treatment of patients with hyperlipidaemia reduces VLCFA levels in X-ALD fibroblasts. Surprisingly, the VLCFA-lowering effect was independent of PPAR activation and not caused by the increase in either mitochondrial or peroxisomal fatty acid β-oxidation capacity. In fact, our results show that bezafibrate reduces VLCFA synthesis by decreasing the synthesis of C26:0 through a direct inhibition of fatty acid elongation activity. Taken together, our data indicate bezafibrate as a potential pharmacotherapeutic treatment for X-ALD. A clinical trial is currently ongoing to evaluate the effect in patients with X-ALD.     

Inhibition of hepatic sulfatase-2 in vivo: a novel strategy to correct diabetic dyslipidemia

Type 2 diabetes mellitus (T2DM) impairs hepatic clearance of atherogenic postprandial triglyceride-rich lipoproteins (TRLs). We recently reported that livers from T2DM db/db mice markedly overexpress the heparan sulfate glucosamine-6-O-endosulfatase-2 (SULF2), an enzyme that removes 6-O sulfate groups from heparan sulfate proteoglycans (HSPGs) and suppresses uptake of TRLs by cultured hepatocytes. In the present study, we evaluated whether Sulf2 inhibition in T2DM mice in vivo could correct their postprandial dyslipidemia. Selective second-generation antisense oligonucleotides (ASOs) targeting Sulf2 were identified. Db/db mice were treated for 5 weeks with Sulf2 ASO (20 or 50 mg/kg per week), nontarget (NT) ASO, or phosphate-buffered saline (PBS). Administration of Sulf2 ASO to db/db mice suppressed hepatic Sulf2 messenger RNA expression by 70%-80% (i.e., down to levels in nondiabetic db/m mice) and increased the ratio of tri- to disulfated disaccharides in hepatic HSPGs (P < 0.05). Hepatocytes isolated from db/db mice on NT ASO exhibited a significant impairment in very-low-density lipoprotein (VLDL) binding that was entirely corrected in db/db mice on Sulf2 ASO. Sulf2 ASO lowered the random, nonfasting plasma triglyceride (TG) levels by 50%, achieving nondiabetic values. Most important, Sulf2 ASO treatment flattened the plasma TG excursions in db/db mice after corn-oil gavage (iAUC, 1,500 ± 470 mg/dL·h for NT ASO versus 160 ± 40 mg/dL · h for Sulf2 ASO\P < 0.01). CONCLUSIONS: Despite extensive metabolic derangements in T2DM mice, inhibition of a single dys-regulated molecule, SULF2, normalizes the VLDL-binding capacity of their hepatocytes and abolishes postprandial hypertriglyceridemia. These findings provide a key proof of concept in vivo to support Sulf2 inhibition as an attractive strategy to improve metabolic dyslipidemia.     

Clinical outcome following Transcatheter Aortic Valve Implantation in patients with impaired left ventricular systolic function

Objectives: To determine the prevalence of impaired left ventricular (LV) systolic function and its impact on the in‐hospital and long‐term outcome in patients who underwent Transcatheter Aortic Valve Implantation (TAVI). Background: Although impaired LV function may be considered a contra‐indication for aortic valve replacement, the hemodynamic characteristics of transcatheter valves may offer procedural and long‐term clinical benefit in such patients. Methods: 230 consecutive patients underwent TAVI with the Medtronic‐CoreValve System. Impaired LV function was defined by a Left Ventricular Ejection Fraction (LVEF) ≤ 35% (European Multicenter Study on Operative Risk Stratification and Long‐term Outcome in patients with Low‐Flow/Low‐Gradient Aortic Stenosis). Study endpoints were selected and defined according to the Valve Academic Research Consortium recommendations. Results: Compared with patients with a LVEF > 35% (n = 197), those with LVEF ≤ 35% (n = 33) were more often male (78.8 % vs. 46.7%, P < 0.001), more symptomatic (NYHA class III or IV, 97.0% vs. 77.2%, P = 0.008) and had a higher prevalence of prior coronary artery disease (63.6% vs. 43.1%, P = 0.029). The Logistic EuroSCORE was 14.8% and 22.8, respectively (P = 0.012). No difference was observed between the two groups in in‐hospital or 30‐day mortality (3.0% vs. 9.6%, P = 0.21), the Combined Safety Endpoint at 30 days (24.2% and 24.4%, P = 0.99) and survival free from readmission at one year (69.2% and 69.7%, P = 0.85). After adjustment, LVEF ≤ 35% was not associated with an increased risk of 30‐day mortality, in‐hospital complications and survival free from readmission at follow‐up. Conclusion: The immediate and long‐term outcome after TAVI did not differ between patients with an impaired and preserved LVEF. LVEF ≤ 35% did not predict adverse immediate and long‐term outcome. These findings suggest that TAVI should not be withheld in selected patients with impaired LV function. © 2011 Wiley Periodicals, Inc.     

Salmonella Subtypes with Increased MICs for Azithromycin in Travelers Returned to the Netherlands

Antimicrobial susceptibility was analyzed for 354 typhoidal Salmonella isolates collected during 1999–2012 in the Netherlands. In 16.1% of all isolates and in 23.8% of all isolates that showed increased MICs for ciprofloxacin, the MIC for azithromycin was increased. This resistance may complicate empirical treatment of enteric fever.