Nucleotide sugars correlate with leukocyte telomere length as part of a dyskeratosis congenita metabolomic plasma signature.

Not available.

Ion-Pairing Chromatography and Amine Derivatization Provide Complementary Approaches for the Targeted LC-MS Analysis of the Polar Metabolome.

Liquid chromatography coupled to mass spectrometry is a key metabolomics/metabonomics technology. Reversed-phase liquid chromatography (RPLC) is very widely used as a separation step, but typically has poor retention of highly polar metabolites. Here, we evaluated the combination of two alternative methods for improving retention of polar metabolites based on 6-aminoquinoloyl-N-hydroxysuccinidimyl carbamate derivatization for amine groups, and ion-pairing chromatography (IPC) using tributylamine as an ion-pairing agent to retain acids. We compared both of these methods to RPLC and also to each other, for targeted analysis using a triple-quadrupole mass spectrometer, applied to a library of ca. 500 polar metabolites. IPC and derivatization were complementary in terms of their coverage: combined, they improved the proportion of metabolites with good retention to 91%, compared to just 39% for RPLC alone. The combined method was assessed by analyzing a set of liver extracts from aged male and female mice that had been treated with the polyphenol compound ampelopsin. Not only were a number of significantly changed metabolites detected, but also it could be shown that there was a clear interaction between ampelopsin treatment and sex, in that the direction of metabolite change was opposite for males and females.

Pathway analysis in metabolomics: Recommendations for the use of over-representation analysis.

Over-representation analysis (ORA) is one of the commonest pathway analysis approaches used for the functional interpretation of metabolomics datasets. Despite the widespread use of ORA in metabolomics, the community lacks guidelines detailing its best-practice use. Many factors have a pronounced impact on the results, but to date their effects have received little systematic attention. Using five publicly available datasets, we demonstrated that changes in parameters such as the background set, differential metabolite selection methods, and pathway database used can result in profoundly different ORA results. The use of a non-assay-specific background set, for example, resulted in large numbers of false-positive pathways. Pathway database choice, evaluated using three of the most popular metabolic pathway databases (KEGG, Reactome, and BioCyc), led to vastly different results in both the number and function of significantly enriched pathways. Factors that are specific to metabolomics data, such as the reliability of compound identification and the chemical bias of different analytical platforms also impacted ORA results. Simulated metabolite misidentification rates as low as 4% resulted in both gain of false-positive pathways and loss of truly significant pathways across all datasets. Our results have several practical implications for ORA users, as well as those using alternative pathway analysis methods. We offer a set of recommendations for the use of ORA in metabolomics, alongside a set of minimal reporting guidelines, as a first step towards the standardisation of pathway analysis in metabolomics.

Calm on the surface, dynamic on the inside. Molecular homeostasis of Anabaena sp. PCC 7120 nitrogen metabolism.

Nitrogen sources are all converted into ammonium/ia as a first step of assimilation. It is reasonable to expect that molecular components involved in the transport of ammonium/ia across biological membranes connect with the regulation of both nitrogen and central metabolism. We applied both genetic (i.e., Δamt mutation) and environmental treatments to a target biological system, the cyanobacterium Anabaena sp PCC 7120. The aim was to both perturb nitrogen metabolism and induce multiple inner nitrogen states, respectively, followed by targeted quantification of key proteins, metabolites and enzyme activities. The absence of AMT transporters triggered a substantial whole-system response, affecting enzyme activities and quantity of proteins and metabolites, spanning nitrogen and carbon metabolisms. Moreover, the Δamt strain displayed a molecular fingerprint indicating nitrogen deficiency even under nitrogen replete conditions. Contrasting with such dynamic adaptations was the striking near-complete lack of an externally measurable altered phenotype. We conclude that this species evolved a highly robust and adaptable molecular network to maintain homeostasis, resulting in substantial internal but minimal external perturbations. This analysis provides evidence for a potential role of AMT transporters in the regulatory/signalling network of nitrogen metabolism and the existence of a novel fourth regulatory mechanism controlling glutamine synthetase activity.

Burnout among Interventional Radiologists.

PURPOSE: To characterize burnout, as defined by high emotional exhaustion (EE) or depersonalization (DP), among interventional radiologists using a validated assessment tool. MATERIALS AND METHODS: An anonymous 34-question survey was distributed to interventional radiologists. The survey consisted of demographic and practice environment questions and the 22-item Maslach Burnout Inventory-Human Services Survey (MBI). Interventional radiologists with high scores on EE (≥ 27) or DP (≥ 10) MBI subscales were considered to have a manifestation of career burnout. RESULTS: Beginning on January 7, 2019, 339 surveys were completed over 31 days. Of respondents, 263 (77.6%) identified as male, 75 (22.1%) identified as female, and 1 (0.3%) identified as trans-male. The respondents were interventional radiology attending physicians (298; 87.9%), fellows (20; 5.9%), and residents (21; 6.2%) practicing at academic (136; 40.1%), private (145; 42.8%), and hybrid (58; 17.1%) centers. Respondents worked < 40 hours (15; 4.4%), 40-60 hours (225; 66.4%), 60-80 hours (81; 23.9%), and > 80 hours (18; 5.3%) per week. Mean MBI scores for EE, DP, and personal achievement were 30.0 ± 13.0, 10.6 ± 6.9, and 39.6 ± 6.6. Burnout was present in 244 (71.9%) participants. Identifying as female (odds ratio 2.4; P = .009) and working > 80 hours per week (odds ratio 7.0; P = .030) were significantly associated with burnout. CONCLUSIONS: Burnout is prevalent among interventional radiologists. Identifying as female and working > 80 hours per week were strongly associated with burnout.

Remodelling of microRNAs in colorectal cancer by hypoxia alters metabolism profiles and 5-fluorouracil resistance.

Solid tumours have oxygen gradients and areas of near and almost total anoxia. Hypoxia reduces sensitivity to 5-fluorouracil (5-FU)-chemotherapy for colorectal cancer (CRC). MicroRNAs (miRNAs) are hypoxia sensors and were altered consistently in six CRC cell lines (colon cancer: DLD-1, HCT116 and HT29; rectal cancer: HT55, SW837 and VACO4S) maintained in hypoxia (1 and 0.2% oxygen) compared with normoxia (20.9%). CRC cell lines also showed altered amino acid metabolism in hypoxia and hypoxia-responsive miRNAs were predicted to target genes in four metabolism pathways: beta-alanine; valine, leucine, iso-leucine; aminoacyl-tRNA; and alanine, aspartate, glutamate. MiR-210 was increased in hypoxic areas of CRC tissues and hypoxia-responsive miR-21 and miR-30d, but not miR-210, were significantly increased in 5-FU resistant CRCs. Treatment with miR-21 and miR-30d antagonists sensitized hypoxic CRC cells to 5-FU. Our data highlight the complexity and tumour heterogeneity caused by hypoxia. MiR-210 as a hypoxic biomarker, and the targeting of miR-21 and miR-30d and/or the amino acid metabolism pathways may offer translational opportunities.

Stent Placement Across the Renal Vein Inflow in Patients Undergoing Venous Reconstruction Preserves Renal Function and Renal Vein Patency: Experience in 93 Patients.

PURPOSE: To determine if stent placement across the renal vein inflow affects kidney function and renal vein patency. METHODS: Between June 2008 and September 2016, 93 patients (mean age 39 years, range 15-70; 54 women) with iliocaval occlusion underwent venous stent placement and were retrospectively reviewed. For this analysis, the patients were separated into treatment and control groups: 51 (55%) patients had suprarenal and infrarenal iliocaval venous disease requiring inferior vena cava stent reconstruction across the renal vein inflow (treatment group) and 42 (45%) patients had iliac vein stenting sparing the renal veins (control group). Treatment group patients received Wallstents (n=15), Gianturco Z-stents (n=24), or suprarenal and infrarenal Wallstents such that the renal veins were bracketed with a "renal gap" (n=12). Stenting technical success, stent type, glomerular filtration rate (GFR), and creatinine before and after stent placement were recorded, along with renal vein patency and complications. RESULTS: All procedures were technically successful. In the 51-patient treatment group, 15 (29%) patients received Wallstents and 24 (47%) received Gianturco Z-stents across the renal veins, while 12 (24%) were given a "renal gap" with no stent placement directly across the renal vein inflow. In the control group, 42 patients received iliac vein Wallstents only. Mean prestent GFR was 59±1.8 mL/min/1.73 m2 and mean prestent creatinine was 0.8±0.2 mg/dL for the entire cohort. Mean prestent GFR and creatinine values in the Wallstent, Gianturco Z-stent, and "renal gap" subgroups did not differ from the iliac vein stent group. Mean poststent GFR and creatinine values were 59±3.3 mL/min/1.73 m2 and 0.8±0.3 mg/dL, respectively. There were no differences between mean pre- and poststent GFR (p=0.32) or creatinine (p=0.41) values when considering all patients or when comparing the treatment subgroups and the control group. There were no differences in the poststent mean GFR or creatinine values between the Wallstent (p=0.21 and p=0.34, respectively) and Gianturco Z-stent (p=0.43 and p=0.41, respectively) groups and the "renal gap" group. One patient with a Wallstent across the renal veins developed right renal vein thrombosis 7 days after the procedure. CONCLUSION: Stent placement across the renal vein inflow did not compromise renal function. A very small risk of renal vein thrombosis was seen.

Medical Malpractice in Image-Guided Procedures: An Analysis of 184 Cases.

PURPOSE: To report types and outcomes of a small subset of malpractice lawsuits filed against physicians performing image-guided interventions in the United States. MATERIALS AND METHODS: In total, 1,312 cases involving common image-guided procedures were reviewed from the Westlaw and LexisNexis databases in the United States from 1963 to 2018. Social Security, disability, employment contract, product liability, criminal, and government employment claims were excluded. The final legal cohort comprised 184 (14.0%) cases. They were categorized into vascular (113/184; 61.4%), inferior vena cava filter (n = 22; 12.0%), neurointerventional (n = 13; 7.1%), gastrointestinal and genitourinary (n = 17; 9.2%), foreign body (n = 7; 3.8%), biopsy related (n = 9; 4.9%), and oncologic (n = 3; 1.6%) interventions. Claims were also organized by defendant type and by specialty, complication stage, verdict, and year. RESULTS: From 2001 to 2018, 58.7% of claims (n = 108) were reported. Procedural complications related to arteriography were most commonly litigated (63/113; 55.8%). Claims arising from intra-procedural and early post-procedural complications were common (84/184; 45.7%). Community hospitals were most often named as defendants (61/184; 33.2%). In reported outcomes, courts sided with defendants in 81.9% (104/127) of the cases, similar to national malpractice trends. Unreported outcomes comprised 31% (57/184) of the data. CONCLUSIONS: For the small subset of claims published within national legal databases, intra-procedural and early post-procedural complications after diagnostic arteriography were most commonly litigated. Most (81.9%) claims with reported outcomes sided with the defendant physician.

Total endovenous recanalization and stent reconstruction for naïve non-inferior vena cava filter-associated chronic iliocaval occlusive disease: Placement of 352 venous stents in 69 debilitated patients.

The aim of this study was to report the technical success, adverse events, clinical outcomes, and long-term stent patency of iliocaval stent reconstruction for naïve, non-inferior vena cava (IVC) filter-related, chronic iliocaval thrombosis. A total of 69 patients, including 47 (68%) men, with a mean age of 36 years (range: 8-71 years), underwent first-time iliocaval stent reconstruction for non-IVC filter-associated iliocaval thrombosis. The mean number of prothrombotic risk factors was 2.2 (range: 0-5), including 30 (43%) patients with IVC atresia. Upon initial presentation, the Clinical, Etiology, Anatomy, and Pathophysiology (CEAP) classification was C3 in 55 (80%) patients, C4 in four (5.8%) patients, C5 in one (1.4%) patient, and C6 in seven (10%) patients. Technical aspects of stent reconstruction, technical success, adverse events, 2-week and 6, 12, and 24-month clinical response, and 6, 12, and 24-month primary, primary-assisted, and secondary stent patency rates were recorded. Technical success was defined as recanalization and stent deployment. Adverse events were reported according to the Society of Interventional Radiology classification system. Clinical success was defined as a 1-point decrease in CEAP classification and stent patency was defined by the Cardiovascular and Interventional Radiological Society guidelines. The technical success rate was 100%. There were 352 venous stents deployed during stent reconstructions. One (1.4%) severe, four (5.8%) moderate, and four (5.8%) minor adverse events occurred and median post-procedure hospitalization was 1 day (range: 1-45 days). Clinical success at 2 weeks and 6, 12, and 24 months was 76%, 85%, 87%, and 100%, respectively. The estimated 6, 12, and 24-month primary patency rates were 91%, 88%, and 62%, respectively. The estimated 6, 12, and 24-month primary-assisted patency rates were 98%, 95%, and 81%, respectively. The estimated 6, 12, and 24-month secondary-assisted patency rates were all 100%. In conclusion, iliocaval stent reconstruction is an effective treatment for non-IVC filter-associated chronic iliocaval thrombosis with high rates of technical success, clinical responses, and stent patency.

Percutaneous Embolization of a Saccular Omental Artery Aneurysm.

Omental artery aneurysms are a unique subset of splanchnic artery aneurysms that are associated with intraperitoneal hemorrhage and high mortality rates. Detecting omental artery aneurysms prior to rupture is especially challenging; as such there are limited data surrounding unruptured aneurysms. Various methods of treating ruptured omental artery aneurysms have been previously described including omentectomy and transcatheter arterial embolization. Because of the mortality rate associated with ruptures, elective intervention in unruptured splanchnic artery aneurysms is recommended regardless of their size. This report details the successful embolization of an unruptured omental artery aneurysm utilizing a percutaneous approach.

Endovascular Transpulmonary Retrieval of a Migrated Amplatzer Vascular Plug Following Balloon-Occluded Retrograde Transvenous Obliteration.

Gastric varices are a common manifestation of portal hypertension and are associated with a high rate of mortality and rebleeding. Balloon-occluded retrograde transvenous obliteration (BRTO) is a commonly used method to sclerose gastric varices and has a high clinical success. Common complications following BRTO include portal or splenic vein thrombosis, systemic sclerosant extravasation, pulmonary emboli, and inferior vena cava thrombosis. This report describes a patient with vascular plug migration into the left pulmonary artery with subsequent endovascular retrieval.

Endobronchial Forceps-Assisted Removal of Gianturco Z-Stents from the Right Atrium.

Endovascular treatment of malignant intrahepatic inferior vena cava stenosis involves venoplasty and stenting. Intravascular migration is a complication associated with stents. This technical report describes the retrieval of migrated intracardiac Gianturco Z-stents using rigid endobronchial forceps.

Lower extremity endovenous reconstruction for symptomatic occlusive disease in pediatric patients: techniques, clinical outcomes, and long-term stent patencies.

BACKGROUND: Endovascular stent reconstruction is the standard of care for chronic venous occlusive disease in adults, but it has not been reported in pediatric patients. OBJECTIVE: This study reports the technical success, complications, clinical outcomes, and stent patency of iliocaval stent reconstruction for chronic iliocaval thrombosis in pediatric patients. MATERIALS AND METHODS: Fourteen patients, 13 (93%) male with a mean age of 16.4 years (range: 8-20 years), underwent iliocaval stent reconstruction for chronic iliocaval thrombosis. The mean number of prothrombotic risk factors was 2.5 (range: 0-4), including 7 (50%) patients with inferior vena cava atresia. At initial presentation, the Clinical, Etiology, Anatomy, and Pathophysiology classification (CEAP) score was C3 in 2 (14%) patients, C4 in 11 (79%) patients, and C6 in 1 (7.1%) patient. Time course of presenting symptoms included chronic (>4 weeks) (n=7; 50%) and acute worsening of chronic symptoms (2-4 weeks) (n=7; 50%). Aspects of recanalization and reconstruction, stenting technical success, complications, clinical outcomes and stent patency were recorded. Clinical success was defined as a 1-point decrease in the CEAP. Primary, primary-assisted, and secondary patency were defined by Cardiovascular and Interventional Radiological Society of Europe guidelines. RESULTS: Most procedures employed three access sites (range: 2-4). Intravascular ultrasound was employed in 11 (79%) procedures. Blunt and sharp recanalization techniques were used in 12 (86%) and 2 (14%) patients, respectively. Stenting technical success was 100%. Two (14%) minor adverse events occurred and mean post-procedure hospitalization was 2.8 days (range: 1-8 days). Clinical success rates at 2 weeks, 6 months and 12 months were 85%, 82%, and 83%, respectively. At a mean final clinical follow-up of 88 months (range: 16-231 months), clinical success was 93%. Estimated 6- and 12-month primary stent patencies were 86% and 64%, respectively. Six- and 12-month primary-assisted and secondary stent patency rates were both 100%. CONCLUSION: Iliocaval stent reconstruction is an effective treatment for symptomatic chronic iliocaval thrombosis in pediatric patients with high rates of technical success, 6- and 12-month clinical success, and 6- and 12-month primary-assisted and secondary patency rates.

#VascularSurgery.

BACKGROUND: To characterize the vascular surgery Twitter network. METHODS: A total of 20,841 consecutive tweets by 8,282 unique Twitter accounts regarding vascular surgery from October 23, 2014 to January 15, 2018 were analyzed. Twitter analytics, including activity metrics, content analysis, user characteristics, engagement, and network analysis were performed using Symplur Signals, a health care social media analytics platform. RESULTS: Vascular surgery tweets, the number of users tweeting about vascular surgery, and vascular surgery tweet impressions have increased by an annual average of 77.8%, 55.3%, and 209.1% from 2015 to 2017, respectively. Twitter activity trend analysis showed consistent growth over the study period with an average of 25.7 ± 2.6 additional tweets per month (P < 0.001). As for tweet content, 2,220 tweets (10.7%) were pertaining to patients, and 2,198 tweets (10.5%) were regarding new or innovative topics. 15,422 tweets (74.0%) included links to journals or websites and 6,826 tweets (32.8%) contained at least 1 image. Deep venous thrombosis, pulmonary embolism, diabetes, endovascular interventions, trauma, and practice guidelines were among the most commonly discussed health topics. Physicians composed 5,618 tweets (27%), while patients submitted 2,447 tweets (11.7%). As for engagement, 8,886 tweets (42.6%) were retweets, 11,816 tweets (56.7%) mentioned at least 1 other user, and 786 tweets (3.8%) were replies. Network analysis revealed central hubs to be vascular surgery societies, academic institutions, academic journals, and physicians. CONCLUSIONS: The use of Twitter to discuss vascular surgery is growing rapidly with increasing use by vascular surgeons and vascular medicine physicians. An effort to involve more patients in the vascular surgery Twitter social network may allow for more opportunities to educate, and garner interest and support for vascular surgery.

Identification of hydroxyapatite spherules provides new insight into subretinal pigment epithelial deposit formation in the aging eye.

Accumulation of protein- and lipid-containing deposits external to the retinal pigment epithelium (RPE) is common in the aging eye, and has long been viewed as the hallmark of age-related macular degeneration (AMD). The cause for the accumulation and retention of molecules in the sub-RPE space, however, remains an enigma. Here, we present fluorescence microscopy and X-ray diffraction evidence for the formation of small (0.5-20 µm in diameter), hollow, hydroxyapatite (HAP) spherules in Bruch's membrane in human eyes. These spherules are distinct in form, placement, and staining from the well-known calcification of the elastin layer of the aging Bruch's membrane. Secondary ion mass spectrometry (SIMS) imaging confirmed the presence of calcium phosphate in the spherules and identified cholesterol enrichment in their core. Using HAP-selective fluorescent dyes, we show that all types of sub-RPE deposits in the macula, as well as in the periphery, contain numerous HAP spherules. Immunohistochemical labeling for proteins characteristic of sub-RPE deposits, such as complement factor H, vitronectin, and amyloid beta, revealed that HAP spherules were coated with these proteins. HAP spherules were also found outside the sub-RPE deposits, ready to bind proteins at the RPE/choroid interface. Based on these results, we propose a novel mechanism for the growth, and possibly even the formation, of sub-RPE deposits, namely, that the deposit growth and formation begin with the deposition of insoluble HAP shells around naturally occurring, cholesterol-containing extracellular lipid droplets at the RPE/choroid interface; proteins and lipids then attach to these shells, initiating or supporting the growth of sub-RPE deposits.

GlnK Facilitates the Dynamic Regulation of Bacterial Nitrogen Assimilation.

Ammonium assimilation in Escherichia coli is regulated by two paralogous proteins (GlnB and GlnK), which orchestrate interactions with regulators of gene expression, transport proteins, and metabolic pathways. Yet how they conjointly modulate the activity of glutamine synthetase, the key enzyme for nitrogen assimilation, is poorly understood. We combine experiments and theory to study the dynamic roles of GlnB and GlnK during nitrogen starvation and upshift. We measure time-resolved in vivo concentrations of metabolites, total and posttranslationally modified proteins, and develop a concise biochemical model of GlnB and GlnK that incorporates competition for active and allosteric sites, as well as functional sequestration of GlnK. The model predicts the responses of glutamine synthetase, GlnB, and GlnK under time-varying external ammonium level in the wild-type and two genetic knock-outs. Our results show that GlnK is tightly regulated under nitrogen-rich conditions, yet it is expressed during ammonium run-out and starvation. This suggests a role for GlnK as a buffer of nitrogen shock after starvation, and provides a further functional link between nitrogen and carbon metabolisms.

Rapid screening of cellular stress responses in recombinant Pichia pastoris strains using metabolite profiling.

Heterologous protein production in the yeast Pichia pastoris can be limited by biological responses to high expression levels; the unfolded protein response (UPR) is a key determinant of the success of protein production in this organism. Here, we used untargeted NMR metabolic profiling (metabolomics) of a number of different recombinant strains, carried out in a miniaturized format suitable for screening-level experiments. We identified a number of metabolites (from both cell extracts and supernatants) which correlated well with UPR-relevant gene transcripts, and so could be potential biomarkers for future high-throughput screening of large numbers of P. pastoris clones.

Identification of the Elusive Pyruvate Reductase of Chlamydomonas reinhardtii Chloroplasts.

Under anoxic conditions the green alga Chlamydomonas reinhardtii activates various fermentation pathways leading to the creation of formate, acetate, ethanol and small amounts of other metabolites including d-lactate and hydrogen. Progress has been made in identifying the enzymes involved in these pathways and their subcellular locations; however, the identity of the enzyme involved in reducing pyruvate to d-lactate has remained unclear. Based on sequence comparisons, enzyme activity measurements, X-ray crystallography, biochemical fractionation and analysis of knock-down mutants, we conclude that pyruvate reduction in the chloroplast is catalyzed by a tetrameric NAD(+)-dependent d-lactate dehydrogenase encoded by Cre07.g324550. Its expression during aerobic growth supports a possible function as a 'lactate valve' for the export of lactate to the mitochondrion for oxidation by cytochrome-dependent d-lactate dehydrogenases and by glycolate dehydrogenase. We also present a revised spatial model of fermentation based on our immunochemical detection of the likely pyruvate decarboxylase, PDC3, in the cytoplasm.

Influence of the Crc regulator on the hierarchical use of carbon sources from a complete medium in Pseudomonas.

The Crc protein, together with the Hfq protein, participates in catabolite repression in pseudomonads, helping to coordinate metabolism. Little is known about how Crc affects the hierarchy of metabolite assimilation from complex mixtures. Using proton Nuclear Magnetic Resonance (NMR) spectroscopy, we carried out comprehensive metabolite profiling of culture supernatants (metabolic footprinting) over the course of growth of both Pseudomonas putida and P. aeruginosa, and compared the wild-type strains with deletion mutants for crc. A complex metabolite consumption hierarchy was observed, which was broadly similar between the two species, although with some important differences, for example in sugar utilization. The order of metabolite utilization changed upon inactivation of the crc gene, but even in the Crc-null strains some compounds were completely consumed before late metabolites were taken up. This suggests the presence of additional regulatory elements that determine the time and order of consumption of compounds. Unexpectedly, the loss of Crc led both species to excrete acetate and pyruvate as a result of unbalanced growth during exponential phase, compounds that were later consumed in stationary phase. This loss of carbon during growth helps to explain the contribution of the Crc/Hfq regulatory system to evolutionary fitness of pseudomonads.