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1.  Enhanced Absorption of Insulin Aspart as the Result of a Dispersed Injection Strategy Tested in a Randomized Trial in Type 1 Diabetic Patients 
Diabetes Care  2013;36(4):780-785.
OBJECTIVE
We investigated the impact of two different injection strategies on the pharmacokinetics and pharmacodynamics of insulin aspart in vivo in an open-label, two-period crossover study and verified changes in the surface-to-volume ratio ex vivo.
RESEARCH DESIGN AND METHODS
Before the clinical trial, insulin aspart was injected ex vivo into explanted human abdominal skin flaps. The surface-to-volume ratio of the subcutaneous insulin depot was assessed by microfocus computed tomography that compared 1 bolus of 18 IU with 9 dispersed boluses of 2 IU. These two injection strategies were then tested in vivo, in 12 C-peptide–negative type 1 diabetic patients in a euglycemic glucose clamp (glucose target 5.5 ± 1.1 mmol/L) for 8 h after the first insulin administration.
RESULTS
The ex vivo experiment showed a 1.8-fold higher mean surface-to-volume ratio for the dispersed injection strategy. The maximum glucose infusion rates (GIR) were similar for the two strategies (10 ± 4 vs. 9 ± 4; P = 0.5); however, times to reach maximum GIR and 50% and 10% of the maximum GIR were significantly reduced by using the 9 × 2 IU strategy (68 ± 33 vs. 127 ± 93 min; P = 0.01; 38 ± 9 vs. 49 ± 16 min; P < 0.01; 23 ± 6 vs. 30 ± 10 min; P < 0.05). For 9 × 2 IU, the area under the GIR curve was greater during the first 60 min (219 ± 89 vs. 137 ± 75; P < 0.01) and halved until maximum GIR (242 ± 183 vs. 501 ± 396; P < 0.01); however, it was similar across the whole study period (1,361 ± 469 vs. 1,565 ± 527; P = 0.08).
CONCLUSIONS
A dispersed insulin injection strategy enhanced the effect of a fast-acting insulin analog. The increased surface-to-volume ratio of the subcutaneous insulin depot can facilitate insulin absorption into the vascular system.
doi:10.2337/dc12-1319
PMCID: PMC3609526  PMID: 23193211
2.  Long-Term Implanted cOFM Probe Causes Minimal Tissue Reaction in the Brain 
PLoS ONE  2014;9(3):e90221.
This study investigated the histological tissue reaction to long-term implanted cerebral open flow microperfusion (cOFM) probes in the frontal lobe of the rat brain. Most probe-based cerebral fluid sampling techniques are limited in application time due to the formation of a glial scar that hinders substance exchange between brain tissue and the probe. A glial scar not only functions as a diffusion barrier but also alters metabolism and signaling in extracellular brain fluid. cOFM is a recently developed probe-based technique to continuously sample extracellular brain fluid with an intact blood-brain barrier. After probe implantation, a 2 week healing period is needed for blood-brain barrier reestablishment. Therefore, cOFM probes need to stay in place and functional for at least 15 days after implantation to ensure functionality. Probe design and probe materials are optimized to evoke minimal tissue reaction even after a long implantation period. Qualitative and quantitative histological tissue analysis revealed no continuous glial scar formation around the cOFM probe 30 days after implantation and only a minor tissue reaction regardless of perfusion of the probe.
doi:10.1371/journal.pone.0090221
PMCID: PMC3951198  PMID: 24621608
3.  Periodic Extraction of Interstitial Fluid from the Site of Subcutaneous Insulin Infusion for the Measurement of Glucose: A Novel Single-Port Technique for the Treatment of Type 1 Diabetes Patients 
Abstract
Background
Treatment of type 1 diabetes patients could be simplified if the site of subcutaneous insulin infusion could also be used for the measurement of glucose. This study aimed to assess the agreement between blood glucose concentrations and glucose levels in the interstitial fluid (ISF) that is extracted from the insulin infusion site during periodic short-term interruptions of continuous subcutaneous insulin infusion (CSII).
Subjects and Methods
A perforated cannula (24 gauge) was inserted into subcutaneous adipose tissue of C-peptide-negative type 1 diabetes subjects (n=13) and used alternately to infuse rapid-acting insulin (100 U/mL) and to extract ISF glucose during a fasting period and after ingestion of a standard oral glucose load (75 g).
Results
Although periodically interrupted for extracting glucose (every hour for approximately 10 min), insulin infusion with the cannula was adequate to achieve euglycemia during fasting and to restore euglycemia after glucose ingestion. Furthermore, the ISF-derived estimates of plasma glucose levels agreed well with plasma glucose concentrations. Correlation coefficient and median absolute relative difference values were found to be 0.95 and 8.0%, respectively. Error grid analysis showed 99.0% of all ISF glucose values within clinically acceptable Zones A and B (83.5% Zone A, 15.5% Zone B).
Conclusions
Results show that ISF glucose concentrations measured at the insulin infusion site during periodic short-term interruptions of CSII closely reflect blood glucose levels, thus suggesting that glucose monitoring and insulin delivery may be performed alternately at the same tissue site. A single-port device of this type could be used to simplify and improve glucose management in diabetes.
doi:10.1089/dia.2012.0173
PMCID: PMC3540899  PMID: 23126579
4.  Distribution of CD4pos -, CD8pos – and Regulatory T Cells in the Upper and Lower Gastrointestinal Tract in Healthy Young Subjects 
PLoS ONE  2013;8(11):e80362.
The gastrointestinal immune system is involved in the development of several autoimmune-mediated diseases, including inflammatory bowel disease, multiple sclerosis, and type 1 diabetes mellitus. Alterations in T-cell populations, especially regulatory T cells (Tregs), are often evident in patients suffering from these diseases. To be able to detect changes in T-cell populations in diseased tissue, it is crucial to investigate T-cell populations in healthy individuals, and to characterize their variation among different regions of the gastrointestinal (GI) tract. While limited data exist, quantitative data on biopsies systematically drawn from various regions of the GI tract are lacking, particularly in healthy young humans. In this report, we present the first systematic assessment of how T cells—including Tregs—are distributed in the gastrointestinal mucosa throughout the GI tract of healthy young humans by means of multi-parameter FACS analysis. Gastroduodenoscopy and colonoscopy were performed on 16 healthy volunteers aged between 18 and 32. Biopsies were drawn from seven GI regions, and were used to determine the frequencies of CD8+-, CD4+- and Tregs in the gastrointestinal mucosa by means of multi-parameter FACS analysis. Our data show that there is significant variation in the baseline T-cell landscape along the healthy human gastrointestinal tract, and that mucosal T-cell analyses from a single region should not be taken as representative of the entire gastrointestinal tract. We show that certain T-cell subsets in the gastrointestinal mucosa vary significantly among regions; most notably, that Tregs are enriched in the appendiceal orifice region and the ascending colon, and that CD8pos T cells are enriched in the gastric mucosa.
doi:10.1371/journal.pone.0080362
PMCID: PMC3827200  PMID: 24265815
5.  Insulin degludec is not associated with a delayed or diminished response to hypoglycaemia compared with insulin glargine in type 1 diabetes: a double-blind randomised crossover study 
Diabetologia  2013;57:40-49.
Aims/hypothesis
Insulin degludec (Des(B30)LysB29(γ-Glu Nε-hexadecandioyl) human insulin; IDeg) is a new basal insulin with an ultra-long flat action profile. The acute physiological responses to hypoglycaemia with IDeg and insulin glargine (A21Gly,B31Arg,B32Arg human insulin; IGlar) were compared.
Methods
Twenty-eight adult type 1 diabetic patients with normal hypoglycaemia awareness (age = 41 ± 12 years, HbA1c = 7.8 ± 0.6% [62.8 ± 7 mmol/mol]) were randomised to once-daily IDeg or IGlar for 5 days in a two-period crossover design. Participants and research staff were blinded to group assignment. Patients were assigned the lowest available randomisation number from a set of blinded randomisation codes provided by the trial sponsor. Hypoglycaemia was induced by administering three times the usual daily insulin dose at midnight on day 5. Plasma glucose (PG) was stabilised by glucose clamp (5.5 mmol/l) for 7–9 h post dosing. Next morning, PG was allowed to decrease stepwise from 5.5 to 3.5 mmol/l (maintained for 30 min) to 2.5 mmol/l (for 15 min). PG was then increased to 3.9 mmol/l (for 120 min), before being returned to baseline. Hypoglycaemic symptom score (HSS), hypoglycaemic awareness, cognitive function, counter-regulatory hormones and vital signs were assessed during each glucose plateau. The primary analysis was to compare IDeg vs IGlar with respect to HSS at nadir PG concentration (2.5 mmol/l).
Results
The full analysis set for treatment comparisons comprised data from all 28 exposed patients. Rates of PG decline and PG at nadir were similar for IDeg and IGlar. No treatment differences in HSS (estimated difference: 0.17 [95% CI −1.71, 2.05]; p > 0.05), cognitive function or awareness were observed at any time. Growth hormone and cortisol responses during hypoglycaemia were greater with IDeg than IGlar (AUC treatment ratio [IDeg/IGlar]: 2.44 [1.30, 4.60], p < 0.01; and 1.23 [1.01, 1.50]; p < 0.05), and adrenaline (epinephrine) responses trended higher (1.40 [0.96, 2.04], p = 0.07). The rates of recovery from hypoglycaemia were similar.
Conclusions/interpretation
IDeg and IGlar elicit comparable symptomatic and cognitive responses to induced hypoglycaemia. IDeg may elicit a moderately greater endocrine response, but times to PG recovery were similar for the two insulins.
Trial registration
ClinicalTrials.gov NCT01002768.
Funding
Novo Nordisk.
doi:10.1007/s00125-013-3056-0
PMCID: PMC3855490  PMID: 24057153
Counter-regulation; Degludec; Glargine; Hormones; Hypoglycaemia; Type 1 diabetes
6.  Vitamin D and Immune Function 
Nutrients  2013;5(7):2502-2521.
Vitamin D metabolizing enzymes and vitamin D receptors are present in many cell types including various immune cells such as antigen-presenting-cells, T cells, B cells and monocytes. In vitro data show that, in addition to modulating innate immune cells, vitamin D also promotes a more tolerogenic immunological status. In vivo data from animals and from human vitamin D supplementation studies have shown beneficial effects of vitamin D on immune function, in particular in the context of autoimmunity. In this review, currently available data are summarized to give an overview of the effects of vitamin D on the immune system in general and on the regulation of inflammatory responses, as well as regulatory mechanisms connected to autoimmune diseases particularly in type 1 diabetes mellitus.
doi:10.3390/nu5072502
PMCID: PMC3738984  PMID: 23857223
vitamin D; autoimmunity; immune cells; adaptive immunity; innate immunity; cholecalciferol; calcitriol; 25(OH)D
7.  Mutations at Ser331 in the HSN type I gene SPTLC1 are associated with a distinct syndromic phenotype 
Mutations in the serine palmitoyltransferase subunit 1 (SPTLC1) gene are the most common cause of hereditary sensory neuropathy type 1 (HSN1). Here we report the clinical and molecular consequences of a particular mutation (p.S331Y) in SPTLC1 affecting a patient with severe, diffuse muscle wasting and hypotonia, prominent distal sensory disturbances, joint hypermobility, bilateral cataracts and considerable growth retardation. Normal plasma sphingolipids were unchanged but 1-deoxy-sphingolipids were significantly elevated. In contrast to other HSN patients reported so far, our findings strongly indicate that mutations at amino acid position Ser331 of the SPTLC1 gene lead to a distinct syndrome.
Highlights
•Novel mutation associated with a distinct new phenotype.•Most interesting because of possible upcoming therapeutic options.•Elevated 1-deoxy-sphingolipids levels.
doi:10.1016/j.ejmg.2013.02.002
PMCID: PMC3682180  PMID: 23454272
HSN; HSAN; SPTLC1; Cataract; Hereditary neuropathy
8.  Comparison of two in vitro systems to assess cellular effects of nanoparticles-containing aerosols 
Inhalation treatment with nanoparticle containing aerosols appears a promising new therapeutic option but new formulations have to be assessed for efficacy and toxicity. We evaluated the utility of a VITRO-CELL®6 PT-CF + PARI LC SPRINT® Baby Nebulizer (PARI BOY) system compared with a conventional MicroSprayer. A549 cells were cultured in the air–liquid interface, exposed to nanoparticle aerosols and characterized by measurement of transepithelial electrical resistance and staining for tight junction proteins. Deposition and distribution rates of polystyrene particles and of carbon nanotubes on the cells were assessed. In addition, cytotoxicity of aerosols containing polystyrene particles was compared with cytotoxicity of polystyrene particles in suspension tested in submersed cultures. Exposure by itself in both exposure systems did not damage the cells. Deposition rates of aerosolized polystyrene particles were about 700 times and that of carbon nanotubes about 4 times higher in the MicroSprayer than in the VITROCELL®6 PT-CF system. Cytotoxicity of amine-functionalized polystyrene nanoparticles was significantly higher when applied as an aerosol on cell cultured in air–liquid interface culture compared with nanoparticle suspensions tested in submersed culture. The higher cytotoxicity of aerosolized nanoparticles underscores the importance of relevant exposure systems.
doi:10.1016/j.tiv.2012.08.008
PMCID: PMC3514486  PMID: 22906573
Nanoparticles; Exposure systems; Inhalation treatment; Nanotoxicology
9.  Comparison of two in vitro systems to assess cellular effects of nanoparticles-containing aerosols 
Toxicology in Vitro  2013;27-360(1):409-417.
Highlights
► A new VITROCELL – Pariboy system was evaluated for testing of aerosolized NPs. ► Deposition rates differed between marker compounds and NPs. ► The manual aerosolizer MicroSprayer was suitable for cytotoxicity testing of NPs. ► Polystyrene nanoparticles acted more cytotoxic as aerosols than as suspensions.
Inhalation treatment with nanoparticle containing aerosols appears a promising new therapeutic option but new formulations have to be assessed for efficacy and toxicity. We evaluated the utility of a VITROCELL®6 PT-CF + PARI LC SPRINT® Baby Nebulizer (PARI BOY) system compared with a conventional MicroSprayer. A549 cells were cultured in the air–liquid interface, exposed to nanoparticle aerosols and characterized by measurement of transepithelial electrical resistance and staining for tight junction proteins. Deposition and distribution rates of polystyrene particles and of carbon nanotubes on the cells were assessed. In addition, cytotoxicity of aerosols containing polystyrene particles was compared with cytotoxicity of polystyrene particles in suspension tested in submersed cultures. Exposure by itself in both exposure systems did not damage the cells. Deposition rates of aerosolized polystyrene particles were about 700 times and that of carbon nanotubes about 4 times higher in the MicroSprayer than in the VITROCELL®6 PT-CF system. Cytotoxicity of amine-functionalized polystyrene nanoparticles was significantly higher when applied as an aerosol on cell cultured in air–liquid interface culture compared with nanoparticle suspensions tested in submersed culture. The higher cytotoxicity of aerosolized nanoparticles underscores the importance of relevant exposure systems.
doi:10.1016/j.tiv.2012.08.008
PMCID: PMC3514486  PMID: 22906573
ALI, air liquid interface; FS, FluoSpheres; FBS, fetal bovine serum; PBS, phosphate buffered saline; DMEM, Dulbecco’s minimal essential medium; ZO-1, zona occludens protein 1; TEER, transepithelial electrical resistance; Nanoparticles; Exposure systems; Inhalation treatment; Nanotoxicology
10.  Spermidine promotes mating and fertilization efficiency in model organisms 
Cell Cycle  2013;12(2):346-352.
Spermidine is a naturally occurring polyamine involved in multiple biological processes, including DNA metabolism, autophagy and aging. Like other polyamines, spermidine is also indispensable for successful reproduction at several stages. However, a direct influence on the actual fertilization process, i.e., the fusion of an oocyte with a spermatocyte, remains uncertain. To explore this possibility, we established the mating process in the yeast Saccharomyces cerevisiae as a model for fertilization in higher eukaryotes. During human fertilization, the sperm capacitates and the acrosome reaction is necessary for penetration of the oocyte. Similarly, sexually active yeasts form a protrusion called “shmoo” as a prerequisite for mating. In this study, we demonstrate that pheromone-induced shmoo formation requires spermidine. In addition, we show that spermidine is essential for mating in yeast as well as for egg fertilization in the nematode Caenorhabditis elegans. In both cases, this occurs independently from autophagy. In synthesis, we identify spermidine as an important mating component in unicellular and multicellular model organisms, supporting an unprecedented evolutionary conservation of the mechanisms governing fertilization-related cellular fusion.
doi:10.4161/cc.23199
PMCID: PMC3575463  PMID: 23255134
Caenorhabditis elegans; spermidine; mating; fertilization; Saccharomyces cerevisiae; shmoo; autophagy; sexual reproduction
11.  Correction of vitamin D deficiency in critically ill patients - VITdAL@ICU study protocol of a double-blind, placebo-controlled randomized clinical trial 
Background
Vitamin D deficiency is associated with multiple adverse health outcomes including increased morbidity and mortality in the general population and in critically ill patients. However, no randomized controlled trial has evaluated so far whether treatment with sufficiently large doses of vitamin D can improve clinical outcome of patients in an intensive care setting.
Methods/design
The VITdAL@ICU trial is an investigator-initiated, non-commercial, double-blind, placebo-controlled randomized clinical trial. This study compares high-dose oral cholecalciferol (vitamin D3) versus placebo treatment in a mixed population of 480 critically ill patients with low 25-hydroxyvitamin-D levels at study enrollment (≤ 20ng/ml). Following an initial loading dose of 540,000 IU of vitamin D3, patients receive 90,000 IU of vitamin D3 on a monthly basis for 5 months. The study is designed to compare clinical outcome in the two study arms with the primary endpoint being length of hospital stay. Secondary endpoints include among others length of ICU stay, the percentage of patients with 25(OH)D levels > 30 ng/ml at day 7, ICU and hospital mortality and duration of mechanical ventilation. We describe here the VITdAL@ICU study protocol for the primary report.
Discussion
This trial is designed to evaluate whether high-dose vitamin D3 is able to improve morbidity and mortality in a mixed population of adult critically ill patients and correct vitamin D deficiency safely.
Trial registration
ClinicalTrials: NCT01130181
doi:10.1186/1472-6823-12-27
PMCID: PMC3534412  PMID: 23134762
Critical Illness; Vitamin D deficiency; Cholecalciferol; Vitamin D; Critical care; Intensive care; Vitamin D3
12.  Action of polystyrene nanoparticles of different sizes on lysosomal function and integrity 
Background
Data from environmental exposure to nanoparticles (NPs) suggest that chronic exposure may increase the incidence of lung, cardiovascular and neurodegenerative diseases. Impairment of cell function by intracellular accumulation of NPs is also suspected. Many types of NPs have been detected in the endosomal-lysosomal system and, upon repeated exposure, alterations of the endosomal-lysosomal system may occur. To identify such effects we compared the effect of carboxyl polystyrene particles (CPS) of different sizes (20-500 nm) on lysosomes of the endothelial cell line EAhy926 after short (24h) and long (72h-96h) exposure times. Lysosomal localization of CPS, as well as lysosomal pH, lysosomal membrane integrity, morphology of the endosomal-lysosomal system and activities of the lysosomal enzymes,cathepsin B and sulfatases, upon exposure to CPS were recorded.
Results
CPS in sizes ≤100 nm showed high co-localization with lysosomes already after 4h, larger CPS after 24h. None of the particles at non-cytotoxic concentrations caused marked changes in lysosomal pH or destroyed lysosomal membrane integrity. At 24h of exposure, 20 nm CPS induced significant dilatation of the endosomal-lysosomal system and reduced activity of lysosomal sulfatases. After 72h, these alterations were less pronounced.
Conclusions
Despite accumulation in lysosomes CPS induced only small changes in lysosomes. Upon longer contact, these changes are even less pronounced. The presented panel of assays may serve to identify effects on lysosomes also for other NPs.
doi:10.1186/1743-8977-9-26
PMCID: PMC3425083  PMID: 22789069
Nanoparticles; Lysosomes; Cathepsin B; Lysosomal sulfatase; Accumulation
13.  Fibulin-5 mutations link inherited neuropathies, age-related macular degeneration and hyperelastic skin 
Brain : a journal of neurology  2011;134(Pt 6):1839-1852.
To identify the disease-causing gene responsible for an autosomal dominantly inherited Charcot–Marie–Tooth neuropathy subtype in a family excluded for mutations in the common Charcot–Marie–Tooth genes, we used array-based sequence capture to simultaneously analyse the disease-linked protein coding exome at chromosome 14q32. A missense mutation in fibulin-5, encoding a widely expressed constituent of the extracellular matrix that has an essential role in elastic fibre assembly and has been shown to cause cutis laxa, was detected as the only novel non-synonymous sequence variant within the disease interval. Screening of 112 index probands with unclassified Charcot–Marie–Tooth neuropathies detected two further fibulin-5 missense mutations in two families with Charcot–Marie–Tooth disease and hyperextensible skin. Since fibulin-5 mutations have been described in patients with age-related macular degeneration, an additional 300 probands with exudative age-related macular degeneration were included in this study. Two further fibulin-5 missense mutations were identified in six patients. A mild to severe peripheral neuropathy was detected in the majority of patients with age-related macular degeneration carrying mutations in fibulin-5. This study identifies fibulin-5 as a gene involved in Charcot–Marie–Tooth neuropathies and reveals heterozygous fibulin-5 mutations in 2% of our patients with age-related macular degeneration. Furthermore, it adumbrates a new syndrome by linking concurrent pathologic alterations affecting peripheral nerves, eyes and skin to mutations in the fibulin-5 gene.
doi:10.1093/brain/awr076
PMCID: PMC3272386  PMID: 21576112
age-related macular degeneration; CMT; cutis laxa; fibulin-5; neuropathy
14.  Further evidence for genetic heterogeneity of distal HMN type V, CMT2 with predominant hand involvement and Silver syndrome 
Journal of the neurological sciences  2007;263(1-2):100-106.
Objective
Distal hereditary motor neuropathy type V (dHMN-V) and Charcot–Marie–Tooth syndrome (CMT) type 2 presenting with predominant hand involvement, also known as CMT2D and Silver syndrome (SS) are rare phenotypically overlapping diseases which can be caused by mutations in the Berardinelli–Seip Congenital Lipodystrophy 2 (BSCL2) and in the glycyl-tRNA synthetase encoding (GARS) genes. Mutations in the heat-shock proteins HSPB1 and HSPB8 can cause related distal hereditary motor neuropathies (dHMN) and are considered candidates for dHMN-V, CMT2, and SS.
Design
To define the frequency and distribution of mutations in the GARS, BSCL2, HSPB1 and HSPB8 genes we screened 33 unrelated sporadic and familial patients diagnosed as either dHMN-V, CMT2D or SS. Exon 3 of the BSCL2 gene was screened in further 69 individuals with an unclassified dHMN phenotype or diagnosed as hereditary spastic paraplegia (HSP) complicated by pure motor neuropathy.
Results
Four patients diagnosed with dHMN-Vor SS carried known heterozygous BSCL2 mutations (N88S and S90L). In one dHMN-V patient we detected a putative GARS mutation (A57V). No mutations were detected in HSPB1 and HSPB8. The diagnostic yield gained in the series of 33 probands was 12% for BSCL2 mutations and 3% for GARS mutations. In the series of unclassified dHMN and complicated HSP cases no mutations were found.
Conclusions
Our data confirm that most likely only two mutations (N88S, S90L) in exon 3 of BSCL2 may lead to dHMN-V or SS phenotypes. Mutations in GARS, HSPB1 and HSPB8. are not a common cause of dHMN-V, SS and CMT2D. We would therefore suggest that a genetic testing of dHMN-V and SS patients should begin with screening of exon 3 of the BSCL2 gene. Screening of the GARS gene is useful in patients with CMT2 with predominant hand involvement and dHMN-V. The rather low frequencies of BSCL2, GARS, HSPB1 and HSPB8 mutations in dHMN-V, CMT2D and SS patients strongly point to further genetic heterogeneity of these related disorders.
doi:10.1016/j.jns.2007.06.047
PMCID: PMC3272403  PMID: 17663003
Charcot–Marie–Tooth disease type 2D; CMT2; Distal hereditary motor neuropathy; dHMN; BSCL2; GARS; HSPB1; HSPB8
15.  SNP array-based whole genome homozygosity mapping as the first step to a molecular diagnosis in patients with Charcot-Marie-Tooth disease 
Journal of Neurology  2011;259(3):515-523.
Considerable non-allelic heterogeneity for autosomal recessively inherited Charcot-Marie-Tooth (ARCMT) disease has challenged molecular testing and often requires a large amount of work in terms of DNA sequencing and data interpretation or remains unpractical. This study tested the value of SNP array-based whole-genome homozygosity mapping as a first step in the molecular genetic diagnosis of sporadic or ARCMT in patients from inbred families or outbred populations with the ancestors originating from the same geographic area. Using 10 K 2.0 and 250 K Nsp Affymetrix SNP arrays, 15 (63%) of 24 CMT patients received an accurate genetic diagnosis. We used our Java-based script eHoPASA CMT—easy Homozygosity Profiling of SNP arrays for CMT patients to display the location of homozygous regions and their extent of marker count and base-pairs throughout the whole genome. CMT4C was the most common genetic subtype with mutations detected in SH3TC2, one (p.E632Kfs13X) appearing to be a novel founder mutation. A sporadic patient with severe CMT was homozygous for the c.250G > C (p.G84R) HSPB1 mutation which has previously been reported to cause autosomal dominant dHMN. Two distantly related CMT1 patients with early disease onset were found to carry a novel homozygous mutation in MFN2 (p.N131S). We conclude that SNP array-based homozygosity mapping is a fast, powerful, and economic tool to guide molecular genetic testing in ARCMT and in selected sporadic CMT patients.
Electronic supplementary material
The online version of this article (doi:10.1007/s00415-011-6213-8) contains supplementary material, which is available to authorized users.
doi:10.1007/s00415-011-6213-8
PMCID: PMC3296015  PMID: 21892769
Autosomal recessive CMT; Homozygosity mapping; SNP array; Hereditary neuropathies; Gene
16.  SNP-array based whole genome homozygosity mapping: A quick and powerful tool to achieve an accurate diagnosis in LGMD2 patients☆ 
A large number of novel disease genes have been identified by homozygosity mapping and the positional candidate approach. In this study we used single nucleotide polymorphism (SNP) array-based, whole genome homozygosity mapping as the first step to a molecular diagnosis in the highly heterogeneous muscle disease, limb girdle muscular dystrophy (LGMD). In a consanguineous family, both affected siblings showed homozygous blocks on chromosome 15 corresponding to the LGMD2A locus. Direct sequencing of CAPN3, encoding calpain-3, identified a homozygous deletion c.483delG (p.Ile162SerfsX17). In a sporadic LGMD patient complete absence of caveolin-3 on Western blot was observed. However, a mutation in CAV3 could not be detected. Homozygosity mapping revealed a large homozygous block at the LGMD2I locus, and direct sequencing of FKRP encoding fukutin-related-protein detected the common homozygous c.826 C > A (p.Leu276Ile) mutation. Subsequent re-examination of this patient's muscle biopsy showed aberrant α-dystroglycan glycosylation. In summary, we show that whole-genome homozygosity mapping using low cost SNP arrays provides a fast and non-invasive method to identify disease-causing mutations in sporadic patients or sibs from consanguineous families in LGMD2. Furthermore, this is the first study describing that in addition to PTRF, encoding polymerase I and transcript release factor, FKRP mutations may cause secondary caveolin-3 deficiency.
doi:10.1016/j.ejmg.2010.12.003
PMCID: PMC3085821  PMID: 21172462
CAPN3; CAV3; FKRP; Homozygosity mapping; LGMD2; SNP array
17.  Glucose Levels at the Site of Subcutaneous Insulin Administration and Their Relationship to Plasma Levels 
Diabetes Care  2010;33(4):833-838.
OBJECTIVE
To examine insulin's effect on the tissue glucose concentration at the site of subcutaneous insulin administration.
RESEARCH DESIGN AND METHODS
A CMA-60 microdialysis (MD) catheter and a 24-gauge microperfusion (MP) catheter were inserted into the subcutaneous adipose tissue of fasting, healthy subjects (n = 5). Both catheters were perfused with regular human insulin (100 units/ml) over a 6-h period and used for glucose sampling and simultaneous administration of insulin at sequential rates of 0.33, 0.66, and 1.00 units/h (each rate was used for 2 h). Before and after the insulin delivery period, both catheters were perfused with an insulin-free solution (5% mannitol) for 2 h and used for glucose sampling only. Blood plasma glucose was clamped at euglycemic levels during insulin delivery.
RESULTS
Start of insulin delivery with MD and MP catheters resulted in a decline of the tissue glucose concentration and the tissue-to-plasma glucose ratio (TPR) for ∼60 min (P < 0.05). However, during the rest of the 6-h period of variable insulin delivery, tissue glucose concentration paralleled the plasma glucose concentration, and the TPR for MD and MP catheters remained unchanged at 83.2 ± 3.1 and 77.1 ± 4.8%, respectively. After subsequent switch to insulin-free perfusate, tissue glucose concentration and TPR increased slowly and reattained preinsulin delivery levels by the end of the experiments.
CONCLUSIONS
The results show the attainment of a stable TPR value at the site of insulin administration, thus indicating that insulin delivery and glucose sensing may be performed simultaneously at the same adipose tissue site.
doi:10.2337/dc09-1531
PMCID: PMC2845037  PMID: 20097778
18.  Short-term effects of high-dose oral vitamin D3 in critically ill vitamin D deficient patients: a randomized, double-blind, placebo-controlled pilot study 
Critical Care  2011;15(2):R104.
Introduction
Vitamin D deficiency is encountered frequently in critically ill patients and might be harmful. Current nutrition guidelines recommend very low vitamin D doses. The objective of this trial was to evaluate the safety and efficacy of a single oral high-dose vitamin D3 supplementation in an intensive care setting over a one-week observation period.
Methods
This was a randomized, double-blind, placebo-controlled pilot study in a medical ICU at a tertiary care university center in Graz, Austria. Twenty-five patients (mean age 62 ± 16yrs) with vitamin D deficiency [25-hydroxyvitamin D (25(OH)D) ≤20 ng/ml] and an expected stay in the ICU >48 hours were included and randomly received either 540,000 IU (corresponding to 13.5 mg) of cholecalciferol (VITD) dissolved in 45 ml herbal oil or matched placebo (PBO) orally or via feeding tube.
Results
The mean serum 25(OH)D increase in the intervention group was 25 ng/ml (range 1-47 ng/ml). The highest 25(OH)D level reached was 64 ng/ml, while two patients showed a small (7 ng/ml) or no response (1 ng/ml). Hypercalcemia or hypercalciuria did not occur in any patient. From day 0 to day 7, total serum calcium levels increased by 0.10 (PBO) and 0.15 mmol/L (VITD; P < 0.05 for both), while ionized calcium levels increased by 0.11 (PBO) and 0.05 mmol/L (VITD; P < 0.05 for both). Parathyroid hormone levels decreased by 19 and 28 pg/ml (PBO and VITD, ns) over the seven days, while 1,25(OH)D showed a transient significant increase in the VITD group only.
Conclusions
This pilot study shows that a single oral ultra-high dose of cholecalciferol corrects vitamin D deficiency within 2 days in most patients without causing adverse effects like hypercalcemia or hypercalciuria. Further research is needed to confirm our results and establish whether vitamin D supplementation can affect the clinical outcome of vitamin D deficient critically ill patients.
EudraCT Number
2009-012080-34
German Clinical Trials Register (DRKS)
DRKS00000750
doi:10.1186/cc10120
PMCID: PMC3219377  PMID: 21443793
19.  Use of the Site of Subcutaneous Insulin Administration for the Measurement of Glucose in Patients With Type 1 Diabetes 
Diabetes Care  2009;33(3):595-601.
OBJECTIVE
To simplify and improve the treatment of patients with type 1 diabetes, we ascertained whether the site of subcutaneous insulin infusion can be used for the measurement of glucose.
RESEARCH DESIGN AND METHODS
Three special indwelling catheters (24-gauge microperfusion [MP] catheters) were inserted into the subcutaneous adipose tissue of subjects with type 1 diabetes (n = 10; all C-peptide negative). One MP catheter was perfused with short-acting insulin (100 units/ml, Aspart) and used for insulin delivery and simultaneous glucose sampling during an overnight fast and after ingestion of a standard glucose load (75 g). As controls, the further two MP catheters were perfused with an insulin-free solution (5% mannitol) and used for glucose sampling only. Plasma glucose was measured frequently at the bedside.
RESULTS
Insulin delivery with the MP catheter was adequate to achieve and maintain normoglycemia during fasting and after glucose ingestion. Tissue glucose concentrations derived with the insulin-perfused catheter agreed well with plasma glucose levels. Median correlation coefficient and median absolute relative difference values were found to be 0.93 (interquartile range 0.91–0.97) and 10.9%, respectively. Error grid analysis indicated that the percentage number of tissue values falling in the clinically acceptable range is 99.6%. Comparable analysis results were obtained for the two mannitol-perfused catheters.
CONCLUSIONS
Our data suggest that estimation of plasma glucose concentrations from the glucose levels directly observed at the site of subcutaneous insulin infusion is feasible and its quality is comparable to that of estimating plasma glucose concentrations from glucose levels measured in insulin-unexposed subcutaneous tissue.
doi:10.2337/dc09-1532
PMCID: PMC2827515  PMID: 20040654
20.  An Automated Discontinuous Venous Blood Sampling System for Ex Vivo Glucose Determination in Humans 
Background
Intensive insulin therapy reduces mortality and morbidity in critically ill patients but places great demands on medical staff who must take frequent blood samples for the determination of glucose levels. A cost-effective solution to this resourcing problem could be provided by an effective and reliable automated blood sampling (ABS) system suitable for ex vivo glucose determination.
Method
The primary study aim was to compare the performance of a prototype ABS system with a manual reference system over a 30 h sampling period under controlled conditions in humans. Two venous cannulae were inserted to connect the ABS system and the reference system. Blood samples were taken with both systems at 15, 30, and 60 min intervals and analyzed using a Beckman glucose analyzer. During the study, blood glucose levels were altered through four meal ingestions.
Results
The median Pearson coefficient of correlation between manually and automatically withdrawn blood samples was 0.976 (0.953−0.996). The system error was −3.327 ± 5.546% (−6.03−0.49). Through Clark error grid analysis, 420 data pairs were analyzed, showing that 98.6% of the data were in zone A and 1.4% were in zone B. Insulin titration error grid analysis revealed an acceptable treatment in 100% of cases. A 17.5-fold reduction in the occurrence of blood-withdrawal failures through occluded catheters was moreover achieved by the added implementation in the ABS system of a “keep vein open” saline infusion.
Conclusions
Our study showed that the ABS system described provides a user-friendly, reliable automated means for reproducible and accurate blood sampling from a peripheral vein for blood glucose determination and thus represents a promising alternative to frequent manual blood sampling.
PMCID: PMC2769855  PMID: 20046655
automated; blood; glucose; monitoring; sampling; ex vivo
21.  Clinical Evaluation of Subcutaneous Lactate Measurement in Patients after Major Cardiac Surgery 
Minimally invasive techniques to access subcutaneous adipose tissue for glucose monitoring are successfully applied in type1 diabetic and critically ill patients. During critical illness, the addition of a lactate sensor might enhance prognosis and early intervention. Our objective was to evaluate SAT as a site for lactate measurement in critically ill patients. In 40 patients after major cardiac surgery, arterial blood and SAT microdialysis samples were taken in hourly intervals. Lactate concentrations from SAT were prospectively calibrated to arterial blood. Analysis was based on comparison of absolute lactate concentrations (arterial blood vs. SAT) and on a 6-hour lactate trend analysis, to test whether changes of arterial lactate can be described by SAT lactate. Correlation between lactate readings from arterial blood vs. SAT was highly significant (r2 = 0.71, P < .001). Nevertheless, 42% of SAT lactate readings and 35% of the SAT lactate trends were not comparable to arterial blood. When a 6-hour stabilization period after catheter insertion was introduced, 5.5% of SAT readings and 41.6% of the SAT lactate trends remained incomparable to arterial blood. In conclusion, replacement of arterial blood lactate measurements by readings from SAT is associated with a substantial shortcoming in clinical predictability in patients after major cardiac surgery.
doi:10.1155/2009/390975
PMCID: PMC2778464  PMID: 19946427
22.  A Stepwise Approach toward Closed-Loop Blood Glucose Control for Intensive Care Unit Patients: Results from a Feasibility Study in Type 1 Diabetic Subjects Using Vascular Micro dialysis with Infrared Spectrometry and a Model Predictive Control Algorithm 
Background
Glycemic control can reduce the mortality and morbidity of intensive care patients. The CLINICIP (closed-loop insulin infusion for critically ill patients) project aimed to develop a closed-loop control system for this patient group. Following a stepwise approach, we combined three independently tested subparts to form a semiautomatic closed-loop system and evaluated it with respect to safety and performance aspects by testing it in subjects with type 1 diabetes mellitus (T1DM) in a first feasibility trial.
Methods
Vascular microdialysis, a multianalyte infrared spectroscopic glucose sensor, and a standard insulin infusion pump controlled by an adaptive model predictive control (MPC) algorithm were combined to form a closed-loop device, which was evaluated in four T1DM subjects during 30-hour feasibility studies. The aim was to maintain blood glucose concentration in the target range between 80 and 110 mg/dl.
Results
Mean plasma glucose concentration was 110.5 ± 29.7 mg/dl. The MPC managed to establish normoglycemia within 105 ± 78 minutes after trial start and managed to maintain glucose concentration within the target range for 47% of the time. The hyperglycemic index averaged to 11.9 ± 5.3 mg/dl.
Conclusion
Data of the feasibility trial illustrate the device being effective in controlling glycemia in T1DM subjects. However, the monitoring part of the loop must be improved with respect to accuracy and precision before testing the system in the target population.
PMCID: PMC3192596  PMID: 21880232
CLINICIP; MPC algorithm; spectroscopic glucose sensor; tight glycemic control; vascular microdialysis
23.  SNP array-based whole genome homozygosity mapping as the first step to a molecular diagnosis in patients with Charcot-Marie-Tooth disease 
Journal of neurology  2011;259(3):515-523.
Considerable non-allelic heterogeneity for autosomal recessively inherited Charcot-Marie-Tooth (ARCMT) disease has challenged molecular testing and often requires a large amount of work in terms of DNA sequencing and data interpretation or remains unpractical. This study tested the value of SNP array-based whole-genome homozygosity mapping as a first step in the molecular genetic diagnosis of sporadic or ARCMT in patients from inbred families or outbred populations with the ancestors originating from the same geographic area. Using 10 K 2.0 and 250 K Nsp Affymetrix SNP arrays, 15 (63%) of 24 CMT patients received an accurate genetic diagnosis. We used our Java-based script eHoPASA CMT—easy Homozygosity Profiling of SNP arrays for CMT patients to display the location of homozygous regions and their extent of marker count and base-pairs throughout the whole genome. CMT4C was the most common genetic subtype with mutations detected in SH3TC2, one (p.E632Kfs13X) appearing to be a novel founder mutation. A sporadic patient with severe CMT was homozygous for the c.250G > C (p.G84R) HSPB1 mutation which has previously been reported to cause autosomal dominant dHMN. Two distantly related CMT1 patients with early disease onset were found to carry a novel homozygous mutation in MFN2 (p.N131S). We conclude that SNP array-based homozygosity mapping is a fast, powerful, and economic tool to guide molecular genetic testing in ARCMT and in selected sporadic CMT patients.
doi:10.1007/s00415-011-6213-8
PMCID: PMC3296015  PMID: 21892769
Autosomal recessive CMT; Homozygosity mapping; SNP array; Hereditary neuropathies; Gene
24.  Alterations in the ankyrin domain of TRPV4 cause congenital distal SMA, scapuloperoneal SMA and HMSN2C 
Nature genetics  2009;42(2):160-164.
Spinal muscular atrophies (SMA, also known as hereditary motor neuropathies) and hereditary motor and sensory neuropathies (HMSN) are clinically and genetically heterogeneous disorders of the peripheral nervous system. Here we report that mutations in the TRPV4 gene cause congenital distal SMA, scapuloperoneal SMA, HMSN 2C. We identified three missense substitutions (R269H, R315W and R316C) affecting the intracellular N-terminal ankyrin domain of the TRPV4 ion channel in five families. Expression of mutant TRPV4 constructs in cells from the HeLa line revealed diminished surface localization of mutant proteins. In addition, TRPV4-regulated Ca2+ influx was substantially reduced even after stimulation with 4αPDD, a TRPV4 channel-specific agonist, and with hypo-osmotic solution. In summary, we describe a new hereditary channelopathy caused by mutations in TRPV4 and present evidence that the resulting substitutions in the N-terminal ankyrin domain affect channel maturation, leading to reduced surface expression of functional TRPV4 channels.
doi:10.1038/ng.508
PMCID: PMC3272392  PMID: 20037588
25.  Graz Endocrine Causes of Hypertension (GECOH) study: a diagnostic accuracy study of aldosterone to active renin ratio in screening for primary aldosteronism 
Background
Primary aldosteronism (PA) affects approximately 5 to 10% of all patients with arterial hypertension and is associated with an excess rate of cardiovascular complications that can be significantly reduced by a targeted treatment. There exists a general consensus that the aldosterone to renin ratio should be used as a screening tool but valid data about the accuracy of the aldosterone to renin ratio in screening for PA are sparse. In the Graz endocrine causes of hypertension (GECOH) study we aim to prospectively evaluate diagnostic procedures for PA.
Methods and design
In this single center, diagnostic accuracy study we will enrol 400 patients that are routinely referred to our tertiary care center for screening for endocrine hypertension. We will determine the aldosterone to active renin ratio (AARR) as a screening test. In addition, all study participants will have a second determination of the AARR and will undergo a saline infusion test (SIT) as a confirmatory test. PA will be diagnosed in patients with at least one AARR of ≥ 5.7 ng/dL/ng/L (including an aldosterone concentration of ≥ 9 ng/dL) who have an aldosterone level of ≥ 10 ng/dL after the saline infusion test. As a primary outcome we will calculate the receiver operating characteristic curve of the AARR in diagnosing PA. Secondary outcomes include the test characteristics of the saline infusion test involving a comparison with 24 hours urine aldosterone levels and the accuracy of the aldosterone to renin activity ratio in diagnosing PA. In addition we will evaluate whether the use of beta-blockers significantly alters the accuracy of the AARR and we will validate our laboratory methods for aldosterone and renin.
Conclusion
Screening for PA with subsequent targeted treatment is of great potential benefit for hypertensive patients. In the GECOH study we will evaluate a standardised procedure for screening and diagnosing of this disease.
doi:10.1186/1472-6823-9-11
PMCID: PMC2671510  PMID: 19351411

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