Autosomal recessive hypercholesterolemia in a kindred of Syrian ancestry.

Autosomal recessive hypercholesterolemia is a rare genetic disorder due to homozygosity or compound heterozygosity for mutations in the low-density lipoprotein receptor adapter protein 1 gene (LDLRAP1), resulting in elevated low-density lipoprotein cholesterol (LDL-C) levels, large xanthomas, and increased cardiovascular risk. Here, we describe a Danish family of Syrian ancestry carrying a frameshift mutation in LDLRAP1, previously only described in Sardinia and Sicily in Italy and in Spain. In 2 children homozygous for this mutation, we evaluate the effect of long-term lipid-lowering treatment with atorvastatin as monotherapy or in combination with ezetimibe. At referral to the lipid clinic at Viborg Regional Hospital, 3 of 4 children had LDL-C levels of 468, 538, and 371 mg/dL, respectively, with 1 child already showing cutaneous xanthomas at 10 years of age. For comparison, the fourth child and the parents had LDL-C levels of 85, 116, and 124 mg/dL. Genetic testing revealed that all 3 children with severely elevated LDL-C were homozygous for a rare frameshift mutation in LDLRAP1, p.His144GlnfsTer27 (c.431dupA), whereas the fourth child and both parents were heterozygous for this mutation. Lipid-lowering treatment was started in the 2 oldest children (at 10 and 7 years of age). Atorvastatin (40 mg/d) combined with ezetimibe (10 mg/d) reduced LDL-C by 75% in the first child and resulted in near-complete regression of xanthomas. In the second child, atorvastatin (40 mg/d) as monotherapy reduced LDL-C by 61%. Both regimens were superior to treatment with pravastatin as monotherapy (20 mg/d) and to pravastatin in combination with cholestyramine (2 g twice daily). High-intensity statin therapy alone or in combination with ezetimibe resulted in marked reductions in LDL-C in 2 children homozygous for a rare frameshift mutation in LDLRAP1 and lead to regression of large xanthomas.

Contemporary lipid clinic and achievements in low-density lipoprotein-cholesterol reductions in very high-risk patients.

INTRODUCTION: Numerous studies have shown that lowering of low-density lipoprotein-cholesterol (LDL-C) reduces the risk of cardiovascular disease (CVD). To optimise treatment, some patients are referred to a lipid clinic. The reduction in LDL-C achieved in a lipid clinic in contemporary practice is, however, not well described. The aim of the present study was to assess the LDL-C lowering effect among very high-risk patients with or without statin-associated muscle symptoms (SAMS) after treatment at a specialised lipid clinic endorsing European guidelines. METHODS: Medical records from 653 patients referred to our Lipid Clinic from 1 January 2013 to 1 May 2017 were examined retrospectively. Very high-risk patients were defined as either having CVD or diabetes mellitus Type 2 who were active smokers and/or had hypertension. The reduction in LDL-C and the number of patients reaching the LDL-C treatment target were investigated by comparing baseline data with the most recent values recorded. RESULTS: We identified 208 patients at a very high-risk for CVD. They obtained an LDL-C reduction of 23% corresponding to a reduction in LDL-C of 0.7 mmol/l (p less than 0.001). The percentage of patients reaching their LDL-C goal increased from 13% to 32%. In patients who had experienced SAMS, LDL-C was reduced by 26% corresponding to a reduction in LDL-C of 0.9 mmol/l (p less than 0.001), and the percentage of patients reaching their LDL-C goal increased from 8% to 23%. CONCLUSIONS: Very high-risk patients with or without SAMS obtained a clinically meaningful reduction in LDL-C of approximately 25% owing to their Lipid Clinic treatment. FUNDING: none. TRIAL REGISTRATION: not relevant.

Prevalence of clinical familial hypercholesterolaemia among patients with high cholesterol levels.

INTRODUCTION: Familial hypercholesterolaemia (FH) can be diagnosed using clinical criteria or by direct mutation identification. The prevalence of clinical FH in Danish lipid clinics remains unknown. The objective of this study was to explore the prevalence of clinical FH in patients admitted on suspicion of FH with plasma low-density lipoprotein cholesterol (LDL-C) concentration ≥ 5.0 mmol/l. METHODS: We reviewed the medical records of 653 patients consecutively (from 1 January 2013 to 1 May 2017) referred to the lipid clinic at Viborg Regional Hospital, Denmark. Patients with LDL-C concentration > 4.9 mmol/l were selected. Clinical FH was assessed using the Dutch Lipid Clinic Network (DLCN) and Simon Broome criteria. RESULTS: Using DLCN, 315 patients (median 82% (95% confidence interval (CI): 78-86%)) had possible FH, 33 patients (median 9% (95% CI: 6-11%)) had probable FH and 36 patients (median 9% (95% CI: 6-12%)) had definite FH. Thus, a total of 69 patients (median 18% (95% CI: 14-22%)) had probable/definite FH. Using the Simon Broome criteria, 284 (median 74% (95% CI: 70-78%)) patients did not have FH, 67 patients (median 17% (95% CI: 14-21%)) had possible FH and 33 patients (median 9% (95% CI; 6-11%)) had definite FH, resulting in a total of 100 (median 26% (95% CI: 22-30%)) patients having possible/definite FH. The concordance between DLCN and Simon Broome FH was high among patients with definite FH (> 90%), but low among patients with probable or possible FH. CONCLUSIONS: Clinical FH was common among patients with LDL-C concentration ≥ 5.0 mmol/l referred to a Danish lipid clinic. However, the concordance between the DLCN and the Simon Broome criteria was low in a specialised clinical setting. FUNDING: The study was supported by a SANOFI grant. TRIAL REGISTRATION: not relevant.

A field-portable membrane introduction mass spectrometer for real-time quantitation and spatial mapping of atmospheric and aqueous contaminants.

Environmental concentrations of volatile and semivolatile organic compounds (VOC/SVOCs) can vary dramatically in time and space under the influence of environmental conditions. In an industrial setting, multiple point and diffuse sources can contribute to fugitive emissions. Assessments and monitoring programs using periodic grab sampling provide limited information, often with delay times of days or weeks. We report the development and use of a novel, portable membrane introduction mass spectrometry (MIMS) system capable of resolving and quantifying VOC and SVOCs with high spatial and temporal resolution, in the field, in real-time. An electron impact ionization cylindrical ion trap mass spectrometer modified with a capillary hollow fiber polydimethylsiloxane membrane interface was used for continuous air and water sampling. Tandem mass spectrometry and selected ion monitoring scans performed in series allowed for the quantitation of target analytes, and full scan mode was used to survey for unexpected analytes. Predeployment and in-field external calibrations were combined with a continuously infused internal standard to enable real-time quantitation and monitor instrument performance. The system was operated in a moving vehicle with internet-linked data processing and storage. Software development to integrate MIMS and relevant meta-data for visualization and geospatial presentation in Google Earth is presented. Continuous quantitation enables the capture of transient events that may be missed or under-represented by traditional grab sampling strategies. Real-time geospatial maps of chemical concentration enable adaptive sampling and in-field decision support. Sample datasets presented in this work were collected in Northern Alberta in 2010-2012.

The effect of the earth's and stray magnetic fields on mobile mass spectrometer systems.

Development of small, field-portable mass spectrometers has enabled a rapid growth of in-field measurements on mobile platforms. In such in-field measurements, unexpected signal variability has been observed by the authors in portable ion traps with internal electron ionization. The orientation of magnetic fields (such as the Earth's) relative to the ionization electron beam trajectory can significantly alter the electron flux into a quadrupole ion trap, resulting in significant changes in the instrumental sensitivity. Instrument simulations and experiments were performed relative to the earth's magnetic field to assess the importance of (1) nonpoint-source electron sources, (2) vertical versus horizontal electron beam orientation, and (3) secondary magnetic fields created by the instrument itself. Electron lens focus effects were explored by additional simulations, and were paralleled by experiments performed with a mass spectrometer mounted on a rotating platform. Additionally, magnetically permeable metals were used to shield (1) the entire instrument from the Earth's magnetic field, and (2) the electron beam from both the Earth's and instrument's magnetic fields. Both simulation and experimental results suggest the predominant influence on directionally dependent signal variability is the result of the summation of two magnetic vectors. As such, the most effective method for reducing this effect is the shielding of the electron beam from both magnetic vectors, thus improving electron beam alignment and removing any directional dependency. The improved ionizing electron beam alignment also allows for significant improvements in overall instrument sensitivity.

Measurement of spatial and temporal variation in volatile hazardous air pollutants in Tacoma, Washington, using a mobile membrane introduction mass spectrometry (MIMS) system.

The objective of this study was to use membrane introduction mass spectrometry (MIMS), implemented on a mobile platform, in order to provide real-time, fine-scale, temporally and spatially resolved measurements of several hazardous air pollutants. This work is important because there is now substantial evidence that fine-scale spatial and temporal variations of air pollutant concentrations are important determinants of exposure to air pollution and adverse health outcomes. The study took place in Tacoma, WA during periods of impaired air quality in the winter and summer of 2008 and 2009. Levels of fine particles were higher in winter compared to summer, and were spatially uniform across the study area. Concentrations of vapor phase pollutants measured by membrane introduction mass spectrometry (MIMS), notably benzene and toluene, had relatively uniform spatial distributions at night, but exhibited substantial spatial variation during the day-daytime levels were up to 3-fold higher at traffic-impacted locations compared to a reference site. Although no direct side-by-side comparison was made between the MIMS system and traditional fixed site monitors, the MIMS system typically reported higher concentrations of specific VOCs, particularly benzene, ethylbenzene and naphthalene, compared to annual average concentrations obtained from SUMA canisters and gas chromatographic analysis at the fixed sites.