Publications by authors named "Peter Wagner"

276 Publications

Altitude physiology then (1921) and now (2021): Meat on the bones.

Authors:
Peter D Wagner

Physiol Rev 2022 Jan 27;102(1):323-332. Epub 2021 Sep 27.

University of California San Diego, La Jolla, California.

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http://dx.doi.org/10.1152/physrev.00033.2021DOI Listing
January 2022

An early burst in brachiopod evolution corresponding with significant climatic shifts during the Great Ordovician Biodiversification Event.

Proc Biol Sci 2021 09 1;288(1958):20211450. Epub 2021 Sep 1.

Department of Earth and Atmospheric Sciences and School of Biological Sciences, University of Nebraska, Lincoln, NB 68588, USA.

We employ modified tip-dating methods to date divergence times within the Strophomenoidea, one of the most abundant and species-rich brachiopod clades to radiate during the Great Ordovician Biodiversification Event (GOBE), to determine if significant environmental changes at this time correlate with the diversification of the clade. Models using origination, extinction and sampling rates to estimate prior probabilities of divergence times strongly support both high rates of anatomical change per million years and rapid divergences shortly before the clade first appears in the fossil record. These divergence times indicate much higher rates of cladogenesis than are typical of brachiopods during this interval. The correspondence of high speciation rates and high anatomical disparity suggests punctuated (speciational) change drove the high frequencies of early anatomical change, which in turn suggests increased ecological opportunities rather than shifting developmental constraints account for high rates of anatomical change. The pulse of rapid evolution began coincident with cooling temperatures, the start of major oscillations in sea level and increased levels of atmospheric oxygen. Our results suggest that these factors permitted major geographical and ecological expansion of strophomenoids with intervals of geographical isolation, resulting in elevated speciation rates and corresponding elevated frequencies of punctuated change.
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http://dx.doi.org/10.1098/rspb.2021.1450DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8437024PMC
September 2021

Use of External Comparators for Health Technology Assessment Submissions Based on Single-Arm Trials.

Value Health 2021 Aug 8;24(8):1118-1125. Epub 2021 Jun 8.

EMEA Centre of Excellence for Retrospective Studies, IQVIA, London, England, UK; Faculty of Epidemiology and Population, London School of Hygiene and Tropical Medicine, London, England, UK; Department of Health Policy, London School of Economics and Political Science, London, England, UK.

Background: Single-arm trial (SAT) data is increasingly reviewed for drug approvals by regulators and Health Technology Assessment (HTA) bodies. Supplementary data in the form of external comparators (ECs) can be used to provide clinical context to support these drug evaluations. In this study we characterized HTAs for SAT-based submissions, the use of supplementary EC data and outcomes from HTA review.

Methods: HTA Accelerator database was used to describe SAT-based HTA submissions with decisions (2011-2019).

Results: A total of 433 SAT-based HTA submissions were identified between 2011 and 2019 with a 13-fold increase during this period. Around 65%(283/433) were in oncology or hem-oncology. Around 52%(226/433) of submissions contained some type of EC data, including prior clinical trials (24%, 104) and real-world data (RWD) (20%, 87), but 40%(175) contained no EC data. The overall acceptance rate for SAT-based submissions was 48% and with RWD EC data acceptance was 59%. In the latest 5-year period (2015-2019), use of RWD ECs increased 22% as a proportion of submissions per year, whereas, prior trial ECs decreased (-14%) and use of no EC remained stable (-2%). Between 2015 to 2017 and 2018 to 2019, acceptance rate for RWD ECs increased by 20% (41% in 2015-2017 to 61% in 2018-2019) whereas prior trial EC use decreased by 10% and no EC submissions decreased 16%. Of 226 submissions using ECs, only 29%(66) used an adjusted indirect treatment comparison method.

Conclusions: SAT-based submissions to HTA bodies are rapidly evolving in terms of composition and acceptance. Types of EC and methodological approach used are important determinants of positive outcomes.
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http://dx.doi.org/10.1016/j.jval.2021.01.015DOI Listing
August 2021

Animal-related factors predicting fatal cases of blackleg and gas gangrene in cattle.

Vet Rec 2021 Nov 9;189(10):e558. Epub 2021 Jun 9.

Unit of Veterinary Public Health and Epidemiology, Institute of Food Safety, Food Technology and Veterinary Public Health, University of Veterinary Medicine, Vienna, Austria.

Background: Blackleg and gas gangrene are acute clostridial infections primarily affecting cattle. The objectives of this study were to identify (i) animal-related factors influencing the occurrence and (ii) prognostic pathological findings supporting the differentiation of fatal blackleg and gas gangrene cases in the cattle population from 1998 to 2018 in Styria, Austria.

Methods: Two binomial logistic models were applied to analyse the research questions. Additionally, cross-validations were performed to estimate the accuracy of the predictive models.

Results: Model results show that animal-related factors (i.e., age, geographical discovery location of dead cattle, vaccination status) significantly influence the occurrence of blackleg when compared to gas gangrene. Pathological findings are similar for both diseases.

Conclusions: Model results reveal that using animal-related factors has a better accuracy to predict the fatal cases caused by both pathogens. Thus, the authors recommend not relying on pathological findings as predictive factors in the differentiation between blackleg and gas gangrene in cattle.
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http://dx.doi.org/10.1002/vetr.558DOI Listing
November 2021

COVID-19 Rehabilitation With Herbal Medicine and Cardiorespiratory Exercise: Protocol for a Clinical Study.

JMIR Res Protoc 2021 May 26;10(5):e25556. Epub 2021 May 26.

Centre for Health and Exercise Science Research, Hong Kong Baptist University, Kowloon, Hong Kong.

Background: Recent studies have revealed that many discharged patients with COVID-19 experience ongoing symptoms months later. Rehabilitation interventions can help address the consequences of COVID-19, including medical, physical, cognitive, and psychological problems. To our knowledge, no studies have investigated the effects of rehabilitation following discharge from hospital for patients with COVID-19.

Objective: The specific aims of this project are to investigate the effects of a 12-week exercise program on pulmonary fibrosis in patients recovering from COVID-19. A further aim will be to examine how Chinese herbal medicines as well as the gut microbiome and its metabolites regulate immune function and possibly autoimmune deficiency in the rehabilitation process.

Methods: In this triple-blinded, randomized, parallel-group, controlled clinical trial, we will recruit adult patients with COVID-19 who have been discharged from hospital in Hong Kong and are experiencing impaired lung function and pulmonary function. A total of 172 eligible patients will be randomized into four equal groups: (1) cardiorespiratory exercise plus Chinese herbal medicines group, (2) cardiorespiratory exercise only group, (3) Chinese herbal medicines only group, and (4) waiting list group (in which participants will receive Chinese herbal medicines after 24 weeks). These treatments will be administered for 12 weeks, with a 12-week follow-up period. Primary outcomes include dyspnea, fatigue, lung function, pulmonary function, blood oxygen levels, immune function, blood coagulation, and related blood biochemistry. Measurements will be recorded prior to initiating the above treatments and repeated at the 13th and 25th weeks of the study. The primary analysis is aimed at comparing the outcomes between groups throughout the study period with an α level of .05 (two-tailed).

Results: The trial has been approved by the university ethics committee following the Declaration of Helsinki (approval number: REC/19-20/0504) in 2020. The trial has been recruiting patients. The data collection will be completed in 24 months, from January 1, 2021, to December 31, 2022.

Conclusions: Given that COVID-19 and its sequelae would persist in human populations, important findings from this study would provide valuable insights into the mechanisms and processes of COVID-19 rehabilitation.

Trial Registration: ClinicalTrials.gov NCT04572360; https://clinicaltrials.gov/ct2/show/NCT04572360.

International Registered Report Identifier (irrid): PRR1-10.2196/25556.
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http://dx.doi.org/10.2196/25556DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8158531PMC
May 2021

i stands for internet (and other things), not for inspired O concentration.

Authors:
Peter D Wagner

Am J Physiol Lung Cell Mol Physiol 2021 03;320(3):L467

Department of Medicine, University of California, San Diego, La Jolla, California.

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http://dx.doi.org/10.1152/ajplung.00610.2020DOI Listing
March 2021

Exercise training in COPD: muscle O transport plasticity.

Eur Respir J 2021 08 19;58(2). Epub 2021 Aug 19.

Dept of Internal Medicine, University of Utah, Salt Lake City, UT, USA.

Both convective oxygen (O) transport to, and diffusive transport within, skeletal muscle are markedly diminished in patients with COPD. However, it is unknown how these determinants of peak muscle O uptake (') respond to exercise training in patients with COPD. Therefore, the purpose of this study was to assess the plasticity of skeletal muscle O transport determinants of ' in patients with COPD.Adaptations to 8 weeks of single-leg knee-extensor exercise training were measured in eight patients with severe COPD (mean±sem forced expiratory volume in 1 s (FEV) 0.9±0.1 L) and eight healthy, well-matched controls. Femoral arterial and venous blood samples, and thermodilution-assessed leg blood flow were used to determine muscle O transport and utilisation at maximal exercise pre- and post-training.Training increased ' in both COPD (by ∼26% from 271±29 to 342±35 mL·min) and controls (by ∼32% from 418±37 to 553±41 mL·min), restoring ' in COPD to only ∼80% of pre-training control ' Muscle diffusive O transport increased similarly in both COPD (by ∼38% from 6.6±0.9 to 9.1±0.9 mL·min·mmHg) and controls (by ∼36% from 10.4±0.7 to 14.1±0.8 mL·min·mmHg), with the patients reaching ∼90% of pre-training control values. In contrast, muscle convective O transport increased significantly only in controls (by ∼26% from 688±57 to 865±69 mL·min), leaving patients with COPD (438±45 491±51 mL·min) at ∼70% of pre-training control values.While muscle diffusive O transport in COPD was largely restored by exercise training, ' remained constrained by limited plasticity in muscle convective O transport.
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http://dx.doi.org/10.1183/13993003.04146-2020DOI Listing
August 2021

Relevant Properties of Carbon Support Materials in Successful Fe-N-C Synthesis for the Oxygen Reduction Reaction: Study of Carbon Blacks and Biomass-Based Carbons.

Materials (Basel) 2020 Dec 24;14(1). Epub 2020 Dec 24.

Institute of Chemistry, Carl von Ossietzky University, 26129 Oldenburg, Germany.

Fe-N-C materials are promising non-precious metal catalysts for the oxygen reduction reaction in fuel cells and batteries. However, during the synthesis of these materials less active Fe-containing nanoparticles are formed in many cases which lead to a decrease in electrochemical activity and stability. In this study, we reveal the significant properties of the carbon support required for the successful incorporation of Fe-N-related active sites. The impact of two carbon blacks and two activated biomass-based carbons on the Fe-N-C synthesis is investigated and crucial support properties are identified. Carbon supports having low portions of amorphous carbon, moderate surface areas (>800 m/g) and mesopores result in the successful incorporation of Fe and N on an atomic level and improved oxygen reduction reaction (ORR) activity. A low surface area and especially amorphous parts of the carbon promote the formation of metallic iron species covered by a graphitic layer. In contrast, highly microporous systems with amorphous carbon provoke the formation of less active iron carbides and carbon nanotubes. Overall, a phosphoric acid activated biomass is revealed as novel and sustainable carbon support for the formation of Fe-N sites. Overall, this study provides valuable and significant information for the future development of novel and sustainable carbon supports for Fe-N-C catalysts.
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http://dx.doi.org/10.3390/ma14010045DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7795179PMC
December 2020

The "Bio-Crime Model" of Cross-Border Cooperation Among Veterinary Public Health, Justice, Law Enforcements, and Customs to Tackle the Illegal Animal Trade/Bio-Terrorism and to Prevent the Spread of Zoonotic Diseases Among Human Population.

Front Vet Sci 2020 3;7:593683. Epub 2020 Nov 3.

Central Directorate for Health, Social Policies, and Disabilities, Trieste, Italy.

Illegal animal trade (pet, wildlife, animal products, etc.) is an example of transnational organized crime (T.O.C.) that generates a large business with huge profit margins. This criminal activity causes several negative effects on human health (zoonoses), animal health and welfare, market protection, consumer fraud and may be used as tool of agro/bio-terrorism. Illegal animal trade can facilitate the spread of zoonoses that are defined as diseases and infections that are transmitted by vertebrate animals to man. Humans are affected by more than 1,700 known pathogens: 60% of existing human infectious diseases are zoonotic and at least 75% of emerging infectious diseases of humans have an animal origin and 72% of zoonoses originate from wildlife or exotic animals. The Bio-Crime Project was developed in 2017 by Friuli Venezia Giulia Region (Italy) and Land Carinthia (Austria) together with other public institutions to combat illegal animal trade and to reduce the risk of disease transmission from animals to humans. Project partners agreed that a multi-agency approach was required to tackle the illegal animal trade that was high value, easy to undertake and transnational crime. The Bio-crime model of cross-border cooperation introduces the novel approach of replicating the cooperative framework given by the triad of Veterinary Public Health, Justice and Law Enforcements/Customs across borders using the International Police and Custom Cooperation Centres (IPCCCs) as a connection link among public entities of the neighbor countries. This model has been recognized as a best practice at European level because it can be easily replicated and scaled up without any supplementary cost for Member States.
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http://dx.doi.org/10.3389/fvets.2020.593683DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7670834PMC
November 2020

[Neuropsychological diagnostics of cognitive deficits : Focus on dementia].

Z Gerontol Geriatr 2020 Dec 4;53(8):797-806. Epub 2020 Nov 4.

Klinik für Psychiatrie, Psychotherapie und Psychosomatik, Abteilung Gerontopsychiatrie, AGAPLESION MARKUS KRANKENHAUS, Wilhelm-Epstein-Str. 4, 60431, Frankfurt am Main, Deutschland.

Older people often report a decline in their cognitive functions - memory problems and difficulty finding words are frequently mentioned. In this context it is essential to differentiate between age-related cognitive decline and pathological processes as they occur in the context of dementia. Neuropsychological diagnostics make an important contribution to this distinction. Using cognitive tests, the quality and quantity of cognitive deficits can be determined. Moreover, the cognitive profile can be used to generate hypotheses about the etiology of the cognitive impairment. In order to avoid a misdiagnosis, factors such as drug side effects, loss of vision and hearing, the presence of depressive symptoms or states of delirium should be taken into account.
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http://dx.doi.org/10.1007/s00391-020-01800-8DOI Listing
December 2020

Synergistic effect of vascular endothelial growth factor gene inactivation in endothelial cells and skeletal myofibres on muscle enzyme activity, capillary supply and endurance exercise in mice.

Exp Physiol 2020 12 14;105(12):2168-2177. Epub 2020 Oct 14.

Department of Medicine, University of California, San Diego, CA, USA.

New Findings: What is the central question of this study? Does vascular endothelial growth factor (VEGF) expressed by both endothelial cells and skeletal myofibres maintain the number of skeletal muscle capillaries and regulate endurance exercise? What is the main finding and its importance? VEGF expressed by both endothelial cells and skeletal myofibres is not essential for maintaining capillary number but does contribute to exercise performance.

Abstract: Many chronic diseases lead to exercise intolerance, with loss of skeletal muscle capillaries. While many muscle cell types (myofibres, satellite cells, endothelial cells, macrophages and fibroblasts) express vascular endothelial growth factor (VEGF), most muscle VEGF is stored in myofibre vesicles which can release VEGF to signal VEGF receptor-expressing cells. VEGF gene ablation in myofibres or endothelial cells alone does not cause capillary regression. We hypothesized that simultaneously deleting the endothelial cell (EC) and skeletal myofibre (Skm) VEGF gene would cause capillary regression and impair exercise performance. This was tested in adult mice by simultaneous conditional deletion of the VEGF gene (Skm/EC-VEGF mice) through the use of VEGFLoxP, HSA-Cre-ER and PDGFb-iCre-ER transgenes. These double-deletion mice were compared to three control groups - WT, EC VEGF gene deletion alone and myofibre VEGF gene deletion alone. Three weeks after initiating gene deletion, Skm/EC-VEGF mice, but not SkmVEGF or EC-VEGF mice, reached exhaustion 40 min sooner than WT mice in treadmill tests (P = 0.002). WT, SkmVEGF and EC-VEGF , but not Skm/EC-VEGF , mice gained weight over the 3 weeks. Capillary density, fibre area and capillary: fibre ratio in soleus, plantaris, gastrocnemius and cardiac papillary muscle were similar across the groups. Phosphofructokinase and pyruvate dehydrogenase activities increased only in Skm/EC-VEGF mice. These data suggest that deletion of the VEGF gene simultaneously in endothelial cells and myofibres, while reducing treadmill endurance and despite compensatory augmentation of glycolysis, is not required for muscle capillary maintenance. Reduced endurance remains unexplained, but may possibly be related to a role for VEGF in controlling perfusion of contracting muscle.
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http://dx.doi.org/10.1113/EP088924DOI Listing
December 2020

Knowing How to Act Well in Time.

Authors:
Peter Wagner

J Bioeth Inq 2020 Dec 25;17(4):507-513. Epub 2020 Aug 25.

Catalan Institute for Research and Advanced Studies (ICREA), Barcelona, Spain.

Numerous scholars in the social sciences and humanities have speedily analysed and interpreted the COVID-19-induced social and political crisis. While the commitment to address an urgent topic is to be appreciated, this article suggests that the combination of confidence in the applicability of one's tools and belief in the certainty of the available knowledge can be counter-productive in the face of a phenomenon that in significant respects is unprecedented. Starting out from the plurality of forms of knowledge that are mobilized to analyse COVID-19 and its consequences as well as the lack of any clearly hegemonic knowledge, the article tries to understand how a limited convergence in the politico-medical responses to the crisis emerged, and speculates on what would have happened if this had not been the case. In conclusion, it is argued that this pandemic demands a greater awareness of the uncertainty of our knowledge and of the consequences of our actions, both in terms of being situated in time and of aiming at timeliness.
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http://dx.doi.org/10.1007/s11673-020-10018-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7445714PMC
December 2020

Ventilation-perfusion heterogeneity measured by the multiple inert gas elimination technique is minimally affected by intermittent breathing of 100% O.

Physiol Rep 2020 07;8(13):e14488

Department of Medicine, University of California San Diego, La Jolla, CA, USA.

Proton magnetic resonance (MR) imaging to quantify regional ventilation-perfusion ( ) ratios combines specific ventilation imaging (SVI) and separate proton density and perfusion measures into a composite map. Specific ventilation imaging exploits the paramagnetic properties of O , which alters the local MR signal intensity, in an F O -dependent manner. Specific ventilation imaging data are acquired during five wash-in/wash-out cycles of breathing 21% O alternating with 100% O over ~20 min. This technique assumes that alternating F O does not affect heterogeneity, but this is unproven. We tested the hypothesis that alternating F O exposure increases mismatch in nine patients with abnormal pulmonary gas exchange and increased mismatch using the multiple inert gas elimination technique (MIGET).The following data were acquired (a) breathing air (baseline), (b) breathing alternating air/100% O during an emulated-SVI protocol (eSVI), and (c) 20 min after ambient air breathing (recovery). MIGET heterogeneity indices of shunt, deadspace, ventilation versus ratio, LogSD , and perfusion versus ratio, LogSD were calculated. LogSD was not different between eSVI and baseline (1.04 ± 0.39 baseline, 1.05 ± 0.38 eSVI, p = .84); but was reduced compared to baseline during recovery (0.97 ± 0.39, p = .04). There was no significant difference in LogSD across conditions (0.81 ± 0.30 baseline, 0.79 ± 0.15 eSVI, 0.79 ± 0.20 recovery; p = .54); Deadspace was not significantly different (p = .54) but shunt showed a borderline increase during eSVI (1.0% ± 1.0 baseline, 2.6% ± 2.9 eSVI; p = .052) likely from altered hypoxic pulmonary vasoconstriction and/or absorption atelectasis. Intermittent breathing of 100% O does not substantially alter matching and if SVI measurements are made after perfusion measurements, any potential effects will be minimized.
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http://dx.doi.org/10.14814/phy2.14488DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7340847PMC
July 2020

Effect Of Leaf Extract On Platelet Count In Chronic Immune Thrombocytopenic Purpura: A Case Series.

Integr Med (Encinitas) 2019 Oct;18(5):30-35

Kalispell Regional Medical Center, Kalispell, Montana, USA.

The leaves of have been used to treat thrombocytopenia in Dengue fever in areas where the virus is endemic. This case series describes the use of leaf liquid extract (CPLE) as an adjunctive therapy for four patients receiving standard-of-care treatment for chronic immune thrombocytopenic purpura (ITP). The cases presented here indicate that CPLE may prove beneficial in the management of chronic ITP for patients interested in alternative therapy before progressing to second-line treatments. A larger clinical trial is warranted to evaluate CPLE as an adjunctive therapy in chronic ITP.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7219447PMC
October 2019

Greater exercise tolerance in COPD during acute interval, compared to equivalent constant-load, cycle exercise: physiological mechanisms.

J Physiol 2020 09 16;598(17):3613-3629. Epub 2020 Jun 16.

1st Department of Critical Care Medicine and Pulmonary Services, Evaggelismos Hospital, National and Kapodistrian University of Athens, Greece.

Key Points: Exercise intolerance is common in chronic obstructive pulmonary disease (COPD) patients. In patients with COPD, we compared an interval exercise (IE) protocol (alternating 30 s at 100% peak work rate (WR ) with 30 s at 50% WR ) with moderate-intensity constant-load exercise (CLE) at 75% WR , which yielded the same work rate. Exercise endurance time and total work output were almost twice as high for IE than CLE. At exercise isotime (when work completed was the same between IE and CLE), IE was associated with less dynamic hyperinflation, lower blood lactate concentration, and greater respiratory and locomotor muscle oxygenation, but there were no differences in ventilation or cardiac output. However, at the limit of tolerance for each modality, dynamic hyperinflation was not different between IE and CLE, while blood lactate remained lower and muscle oxygenation higher with IE. Taken together, these findings suggest that dynamic hyperinflation and not muscle-based factors dictate the limits of tolerance in these COPD patients.

Abstract: The relative importance of ventilatory, circulatory and peripheral muscle factors in determining tolerance to exercise in patients with chronic obstructive pulmonary disease (COPD) is not known. In 12 COPD patients (forced expiratory volume in one second: 58 ± 17%pred.) we measured ventilation, cardiac output, dynamic hyperinflation, local muscle oxygenation, blood lactate and time to exhaustion during (a) interval exercise (IE) consisting of 30 s at 100% peak work rate alternating with 30 s at 50%, and (b) constant-load exercise (CLE) at 75% peak work rate, designed to produce the same average work rate. Exercise time was substantially longer during IE than CLE (19.5 ± 4.8 versus 11.4 ± 2.1 min, p = 0.0001). Total work output was therefore greater during IE than CLE (81.3 ± 27.7 versus 48.9 ± 23.8 kJ, p = 0.0001). Dynamic hyperinflation (assessed by changes from baseline in inspiratory capacity, ΔIC) was less during IE than CLE at CLE exhaustion time (isotime, p = 0.009), but was similar at exhaustion (ΔIC : -0.38 ± 0.10 versus ΔIC : -0.33 ± 0.12 l, p = 0.102). In contrast, at isotime, minute ventilation, cardiac output and systemic oxygen delivery did not differ between protocols (P > 0.05). At exhaustion in both protocols, the vastus lateralis and intercostal muscle oxygen saturation were higher in IE than CLE (p = 0.014 and p = 0.0002, respectively) and blood lactate concentrations were lower (4.9 ± 2.4 mmol l versus 6.4 ± 2.2 mmol l , p = 0.039). These results suggest that (1) exercise tolerance with COPD is limited by dynamic hyperinflation; and (2) cyclically lower (50%) effort intervals in IE help to preserve muscle oxygenation and reduce metabolic acidosis compared with CLE at the same average work rate; but these factors do not appear to determine time to exhaustion.
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http://dx.doi.org/10.1113/JP279531DOI Listing
September 2020

A Novel Approach for Mixed Manual/Connected Automated Freeway Traffic Management.

Authors:
Duo Li Peter Wagner

Sensors (Basel) 2020 Mar 22;20(6). Epub 2020 Mar 22.

Institute of Transport Systems, German Aerospace Center (DLR), 12489 Berlin, Germany.

Freeway traffic management and control often rely on input from fixed-point sensors. A sufficiently high sensor density is required to ensure data reliability and accuracy, which results in high installation and maintenance costs. Moreover, fixed-point sensors encounter difficulties to provide spatiotemporally and wide-ranging information due to the limited observable area. This research exploits the utilization of connected automated vehicles (CAVs) as an alternative data source for freeway traffic management. To handle inherent uncertainty associated with CAV data, we develop an interval type 2 fuzzy logic-based variable speed limit (VSL) system for mixed traffic. The simulation results demonstrate that when more 10% CAVs are deployed, the performance of the proposed CAV-based system can approach that of the detector-based system. It is demonstrated in addition that the introduction of CAVs may make VSL obsolete at very high CAV-equipment rates.
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http://dx.doi.org/10.3390/s20061757DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7146304PMC
March 2020

Peripheral Determinants of Oxygen Utilization in Heart Failure With Preserved Ejection Fraction: Central Role of Adiposity.

JACC Basic Transl Sci 2020 Mar 23;5(3):211-225. Epub 2020 Mar 23.

Division of Cardiovascular Medicine, Hospital of the University of Pennsylvania, Philadelphia, Pennsylvania.

The aim of this study was to determine the arteriovenous oxygen content difference (ΔAVo) in adult subjects with and without heart failure with preserved ejection fraction (HFpEF) during systemic and forearm exercise. Subjects with HFpEF had reduced ΔAVo. Forearm diffusional conductance for oxygen, a lumped conductance parameter that incorporates all impediments to the movement of oxygen from red blood cells in skeletal muscle capillaries into the mitochondria within myocytes, was estimated. Forearm diffusional conductance for oxygen was not different among adults with HFpEF, those with hypertension, and healthy control subjects; therefore, diffusional conductance cannot explain the reduced forearm ΔAVo. Instead, adiposity was strongly associated with ΔAVo, suggesting an active role for adipose tissue in reducing exercise capacity in patients with HFpEF.
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http://dx.doi.org/10.1016/j.jacbts.2020.01.003DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7091498PMC
March 2020

Respiratory and locomotor muscle blood flow during exercise in health and chronic obstructive pulmonary disease.

Exp Physiol 2020 12 29;105(12):1990-1996. Epub 2020 Mar 29.

Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, CA, USA.

New Findings: What is the topic of this review? The work presented here focuses mostly on testing the theory of blood flow redistribution from the locomotor to the respiratory muscles during heavy exercise in healthy participants and in patients with COPD. What advances does it highlight? Studies presented and the direct experimental approach to measure muscle blood flow by indocyanine green dye detected by near infrared spectroscopy, show that exercise interferes with respiratory muscle blood flow especially in COPD, but even in healthy.

Abstract: We have developed an indicator-dilution method to measure muscle blood flow at rest and during exercise using the light absorbing tracer indocyanine green dye (ICG) injected as an intravenous bolus, with surface optodes placed over muscles of interest to record the ICG signal by near-infrared spectroscopy. Here we review findings for both quadriceps and intercostal muscle blood flow (measured simultaneously) in trained cyclists and in patients with chronic obstructive pulmonary disease (COPD). During resting hyperpnoea in both athletes and patients, intercostal muscle blood flow increased with ventilation, correlating closely and linearly with the work of breathing, with no change in quadriceps flow. During graded exercise in athletes, intercostal flow at first increased, but then began to fall approaching peak effort. Unexpectedly, in COPD, intercostal muscle blood flow during exercise fell progressively from resting values, contrasting sharply with the response to resting hyperpnoea. During exercise at peak intensity, we found no quadriceps blood flow reduction in favour of the respiratory muscles in either athletes or patients. In COPD at peak exercise, when patients breathed 21% oxygen in helium or 100% oxygen, there was no redistribution of blood flow observed between legs and respiratory muscles in either direction. Evidence of decrease in leg blood flow and increase in respiratory muscle flow was found only when imposing expiratory flow limitation (EFL) during exercise in healthy individuals. However, because EFL caused substantial physiological derangement, lowering arterial oxygen saturation and raising end-tidal and heart rate, these results cannot be projected onto normal exercise.
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http://dx.doi.org/10.1113/EP088104DOI Listing
December 2020

Spatiotemporal cluster and incidence analysis of cattle mortality caused by bovine babesiosis in Styria, Austria, between 1998 and 2016.

Parasitol Res 2020 Mar 25;119(3):1117-1123. Epub 2020 Feb 25.

District Authority of Murau, Bahnhofsviertel 2, 8850, Murau, Austria.

Reported fatal cases of bovine babesiosis (syn.: piroplasmosis, red water fever) in cattle were analyzed to identify spatial and temporal clusters of their incidence in the Austrian province of Styria. Data were collected within a governmental babesiosis compensation program. Diagnosis was performed using a standardized necropsy protocol. Between 1998 and 2016, a total of 1257 cases of fatal babesiosis were registered and compensated. Within the study interval, annual numbers of fatal babesiosis differed significantly among municipalities. Spatiotemporal analysis covering the entire study period revealed one high-risk cluster in the western and central northern region of Styria and a low-risk cluster in the southeastern part of Styria. Annual temporal analysis demonstrated that cases accumulated in June. Annual spatial analysis revealed consistently that cases mainly occurred in the western and central northern regions, whereas they occurred rarely in the southeastern regions. These results should increase awareness and facilitate protective actions against ticks during certain time periods and geographic areas.
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http://dx.doi.org/10.1007/s00436-020-06604-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7075847PMC
March 2020

High-resolution dating of Paleozoic fossils.

Authors:
Peter Wagner

Science 2020 01;367(6475):249

Department of Earth and Atmospheric Sciences, and School of Biological Sciences, University of Nebraska Lincoln, Lincoln, NE 68588-0340, USA.

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http://dx.doi.org/10.1126/science.aba4348DOI Listing
January 2020

Determinants of the diminished exercise capacity in patients with chronic obstructive pulmonary disease: looking beyond the lungs.

J Physiol 2020 02 19;598(3):599-610. Epub 2020 Jan 19.

Department of Internal Medicine, University of Utah, Salt Lake City, UT, USA.

Key Points: Peak oxygen uptake, a primary determinant of prognosis, mortality and quality of life, is diminished in patients with chronic obstructive pulmonary disease (COPD), with mounting evidence supporting an important role for peripheral dysfunction, particularly within skeletal muscle. In patients with severe COPD and activity-matched controls, muscle oxygen transport and utilization were assessed at peak effort during single-leg knee-extensor exercise (KE), where ventilation is assumed to be submaximal. This strategy removes ventilation as the major constraint to exercise capacity in COPD, allowing maximal muscle function to be attained and evaluated. During maximal KE, both convective arterial oxygen delivery to the skeletal muscle microvasculature and subsequent diffusive oxygen delivery to the mitochondria were diminished in patients with COPD compared to control subjects. These findings emphasize the importance of factors, beyond the lungs, that influence exercise capacity in this patient population and may, ultimately, influence the prognosis, mortality and quality of life for patients with COPD.

Abstract: Peak oxygen uptake ( ), a primary determinant of prognosis, mortality and quality of life, is diminished in patients with chronic obstructive pulmonary disease (COPD). Mounting evidence supports an important role of the periphery, particularly skeletal muscle, in the diminished with COPD. However, the peripheral determinants of have not been comprehensively assessed in this cohort. Thus, the hypothesis was tested that both muscle convective and diffusive oxygen (O ) transport, and therefore skeletal muscle peak O uptake ( ), are diminished in patients with COPD compared to matched healthy controls, even when ventilatory limitations (i.e. attainment of maximal ventilation) are minimized by using small muscle mass exercise. Muscle O transport and utilization were assessed at peak exercise from femoral arterial and venous blood samples and leg blood flow (by thermodilution) in eight patients with severe COPD (forced expiratory volume in 1s (FEV ) ± SEM = 0.9 ± 0.1 l, 30% of predicted) and eight controls during single-leg knee-extensor exercise. Both muscle convective O delivery (0.44 ± 0.06 vs. 0.69 ± 0.07 l min , P < 0.05) and muscle diffusive O conductance (6.6 ± 0.8 vs. 10.4 ± 0.9 ml min  mmHg , P < 0.05) were ∼1/3 lower in patients with COPD than controls, resulting in an attenuated in the patients (0.27 ± 0.04 vs. 0.42 ± 0.05 l min , P < 0.05). When cardiopulmonary limitations to exercise are minimized, the convective and diffusive determinants of , at the level of the skeletal muscle, are greatly attenuated in patients with COPD. These findings emphasize the importance of factors, beyond the lungs, that may ultimately influence this population's prognosis, mortality and quality of life.
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http://dx.doi.org/10.1113/JP279135DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6995414PMC
February 2020

Detection of Spin-Vibration States in Single Magnetic Molecules.

Phys Rev Lett 2019 Sep;123(10):106803

Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA.

The spin states of magnetic molecules have advantageous attributes as carriers of quantum information. However, spin-vibration coupling in molecules causes a decay of excited spin states and a loss of spin coherence. Here, we detect excitations of spin-vibration states in single nickelocene molecules on Ag(110) with a scanning tunneling microscope. By transferring a nickelocene to the tip, the joint spin-vibration states with an adsorbed nickelocene were measured. Chemical variations in magnetic molecules offer the opportunity to tune spin-vibration coupling for controlling the spin coherence.
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http://dx.doi.org/10.1103/PhysRevLett.123.106803DOI Listing
September 2019

Precapillary pulmonary gas exchange is similar for oxygen and inert gases.

J Physiol 2019 11 25;597(22):5385-5397. Epub 2019 Aug 25.

Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, CA, USA.

Key Points: Precapillary gas exchange for oxygen has been documented in both humans and animals. It has been suggested that, if precapillary gas exchange occurs to a greater extent for inert gases than for oxygen, shunt and its effects on arterial oxygenation may be underestimated by the multiple inert gas elimination technique (MIGET). We evaluated fractional precapillary gas exchange in canines for O and two inert gases, sulphur hexafluoride and ethane, by measuring these gases in the proximal pulmonary artery, distal pulmonary artery (1 cm proximal to the wedge position) and systemic artery. Some 12-19% of pulmonary gas exchange occurred within small (1.7 mm in diameter or larger) pulmonary arteries and this was quantitatively similar for oxygen, sulphur hexafluoride and ethane. Under these experimental conditions, this suggests only minor effects of precapillary gas exchange on the magnitude of calculated shunt and the associated effect on pulmonary gas exchange estimated by MIGET.

Abstract: Some pulmonary gas exchange is known to occur proximal to the pulmonary capillary, although the magnitude of this gas exchange is uncertain, and it is unclear whether oxygen and inert gases are similarly affected. This has implications for measuring shunt and associated gas exchange consequences. By measuring respiratory and inert gas levels in the proximal pulmonary artery (P), a distal pulmonary artery 1 cm proximal to the wedge position (using a 5-F catheter) (D) and a systemic artery (A), we evaluated precapillary gas exchange in 27 paired samples from seven anaesthetized, ventilated canines. Fractional precapillary gas exchange (F) was quantified for each gas as F = (P - D)/(P - A). The lowest solubility inert gases, sulphur hexafluoride (SF ) and ethane were used because, with higher solubility gases, the P-A difference is sufficiently small that experimental error prevents accurate assessment of F. Distal samples (n = 12) with oxygen (O ) saturation values that were (within experimental error) equal to or above systemic arterial values, suggestive of retrograde capillary blood aspiration, were discarded, leaving 15 for analysis. D was significantly lower than P for SF (D/P = 88.6 ± 18.1%; P = 0.03) and ethane (D/P = 90.6 ± 16.0%; P = 0.04), indicating partial excretion of inert gas across small pulmonary arteries. Distal pulmonary arterial O saturation was significantly higher than proximal (74.1 ± 6.8% vs. 69.0 ± 4.9%; P = 0.03). Fractional precapillary gas exchange was similar for SF , ethane and O (0.12 ± 0.19, 0.12 ± 0.20 and 0.19 ± 0.26, respectively; P = 0.54). Under these experimental conditions, 12-19% of pulmonary gas exchange occurs within the small pulmonary arteries and the extent is similar between oxygen and inert gases.
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http://dx.doi.org/10.1113/JP277793DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6858488PMC
November 2019

Intra-pulmonary arteriovenous anastomoses and pulmonary gas exchange: evaluation by microspheres, contrast echocardiography and inert gas elimination.

J Physiol 2019 11 26;597(22):5365-5384. Epub 2019 Sep 26.

Division of Pulmonary, Critical Care, and Sleep Medicine, Department of Medicine, University of California San Diego, San Diego, USA.

Key Points: Imaging techniques such as contrast echocardiography suggest that anatomical intra-pulmonary arteriovenous anastomoses (IPAVAs) are present at rest and are recruited to a greater extent in conditions such as exercise. IPAVAs have the potential to act as a shunt, although gas exchange methods have not demonstrated significant shunt in the normal lung. To evaluate this discrepancy, we compared anatomical shunt with 25-µm microspheres to contrast echocardiography, and gas exchange shunt measured by the multiple inert gas elimination technique (MIGET). Intra-pulmonary shunt measured by 25-µm microspheres was not significantly different from gas exchange shunt determined by MIGET, suggesting that MIGET does not underestimate the gas exchange consequences of anatomical shunt. A positive agitated saline contrast echocardiography score was associated with anatomical shunt measured by microspheres. Agitated saline contrast echocardiography had high sensitivity but low specificity to detect a ≥1% anatomical shunt, frequently detecting small shunts inconsequential for gas exchange.

Abstract: The echocardiographic visualization of transpulmonary agitated saline microbubbles suggests that anatomical intra-pulmonary arteriovenous anastomoses are recruited during exercise, in hypoxia, and when cardiac output is increased pharmacologically. However, the multiple inert gas elimination technique (MIGET) shows insignificant right-to-left gas exchange shunt in normal humans and canines. To evaluate this discrepancy, we measured anatomical shunt with 25-µm microspheres and compared the results to contrast echocardiography and MIGET-determined gas exchange shunt in nine anaesthetized, ventilated canines. Data were acquired under the following conditions: (1) at baseline, (2) 2 µg kg  min i.v. dopamine, (3) 10 µg kg  min i.v. dobutamine, and (4) following creation of an intra-atrial shunt (in four animals). Right to left anatomical shunt was quantified by the number of 25-µm microspheres recovered in systemic arterial blood. Ventilation-perfusion mismatch and gas exchange shunt were quantified by MIGET and cardiac output by direct Fick. Left ventricular contrast scores were assessed by agitated saline bubble counts, and separately by appearance of 25-µm microspheres. Across all conditions, anatomical shunt measured by 25-µm microspheres was not different from gas exchange shunt measured by MIGET (microspheres: 2.3 ± 7.4%; MIGET: 2.6 ± 6.1%, P = 0.64). Saline contrast bubble score was associated with microsphere shunt (ρ = 0.60, P < 0.001). Agitated saline contrast score had high sensitivity (100%) to detect a ≥1% shunt, but low specificity (22-48%). Gas exchange shunt by MIGET does not underestimate anatomical shunt measured using 25-µm microspheres. Contrast echocardiography is extremely sensitive, but not specific, often detecting small anatomical shunts which are inconsequential for gas exchange.
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http://dx.doi.org/10.1113/JP277695DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6858494PMC
November 2019

Orodispersible minitablets of enalapril for use in children with heart failure (LENA): Rationale and protocol for a multicentre pharmacokinetic bridging study and follow-up safety study.

Contemp Clin Trials Commun 2019 Sep 8;15:100393. Epub 2019 Jun 8.

Institute of Clinical Pharmacy and Pharmacotherapy, Heinrich-Heine-Universität Düsseldorf, Düsseldorf, Germany.

Introduction: Treatment of paediatric heart failure is based on paradigms extensively tested in the adult population assuming similar underlying pathophysiological mechanisms. Angiotensin converting enzyme inhibitors (ACEI) like enalapril are one of the cornerstones of treatment and commonly used off-label in children. Dose recommendations have been extrapolated from adult experience, but the relationship between dose and pharmacokinetics (PK) in (young) children is insufficiently studied. Furthermore, appropriate paediatric formulations are lacking. Within the European collaborative project LENA, a novel formulation of enalapril orodispersible minitablets (ODMT), suitable for paediatric administration, will be tested in (young) children with heart failure due to either dilated cardiomyopathy or congenital heart disease in two pharmacokinetic bridging studies. Paediatric PK data of enalapril and its active metabolite enalaprilat will be obtained. In a follow-up study, the safety of enalapril ODMTs will be demonstrated in patients on long-term treatment of up to 10 months. Furthermore, additional information about pharmacodynamics (PD) and ODMT acceptability will be collected in all three studies.

Methods And Analysis: Phase II/III, open-label, multicentre study. Children with dilated cardiomyopathy (DCM) (n = 25; 1 month to less than 12 years) or congenital heart disease (CHD) (n = 60; 0 to less than 6 years) requiring or already on ACEI will be included. Exclusion criteria include severe heart failure precluding ACEI use, hypotension, renal impairment, hypersensitivity to ACEI. For those naïve to ACEI up-titration to an optimal dose will be performed, those already on ACEI will be switched to an expected equivalent dose of enalapril ODMT and optimised. In the first 8 weeks of treatment, a PK profile will be obtained at the first dose (ACEI naïve patients) or when an optimal dose is reached. Furthermore, population PK will be done with concentrations detected over the whole treatment period. PD and safety data will be obtained at least at 2-weeks intervals. Subsequently, an intended number of 85 patients will be followed-up up to 10 months to demonstrate long-term safety, based on the occurrence of (severe) adverse events and monitoring of vital signs and renal function.

Ethics And Dissemination: Clinical Trial Authorisation and a favourable ethics committee opinion were obtained in all five participating countries. Results of the studies will be submitted for publication in a peer-reviewed journal.

Trial Registration Numbers: EudraCT 2015-002335-17, EudraCT 2015-002396-18, EudraCT 2015-002397-21.
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http://dx.doi.org/10.1016/j.conctc.2019.100393DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6586986PMC
September 2019

Probing and imaging spin interactions with a magnetic single-molecule sensor.

Science 2019 05 16;364(6441):670-673. Epub 2019 May 16.

Department of Physics and Astronomy, University of California, Irvine, CA 92697-4575, USA.

Magnetic single atoms and molecules are receiving intensifying research focus because of their potential as the smallest possible memory, spintronic, and qubit elements. Scanning probe microscopes used to study these systems have benefited greatly from new techniques that use molecule-functionalized tips to enhance spatial and spectroscopic resolutions and enable new sensing capabilities. We demonstrate a microscopy technique that uses a magnetic molecule, Ni(cyclopentadienyl), adsorbed at the apex of a scanning probe tip, to sense exchange interactions with another molecule adsorbed on a Ag(110) surface in a continuously tunable fashion in all three spatial directions. We further used the probe to image contours of exchange interaction strength, revealing angstrom-scale regions where the quantum states of two magnetic molecules strongly mix. Our results pave the way for new nanoscale imaging capabilities based on magnetic single-molecule sensors.
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http://dx.doi.org/10.1126/science.aaw7505DOI Listing
May 2019

Detection and Characterization of Anharmonic Overtone Vibrations of Single Molecules on a Metal Surface.

Phys Rev Lett 2019 Mar;122(10):106801

Department of Physics and Astronomy, University of California, Irvine, California 92697-4575, USA.

Inelastic electron tunneling spectroscopy (IETS) with the scanning tunneling microscope (STM) is a powerful technique used to characterize the vibration and spin states at the single-molecule level. While IETS lacks hard selection rules, historically it has been assumed that vibrational overtones are rarely seen or even absent. Here we provide definitive experimental evidence that the hindered rotation overtone excitation of carbon monoxide molecules adsorbed on Ag(110) can be detected with STM-IETS via isotope substitution. We also demonstrate that the anharmonicity of the overtone excitation can be characterized and compared between adsorption sites and find evidence of anisotropy in the vibrational anharmonicity for CO adsorbed on the [11[over ¯]0] step edge.
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http://dx.doi.org/10.1103/PhysRevLett.122.106801DOI Listing
March 2019

Cardiac output measurement during exercise in COPD: A comparison of dye dilution and impedance cardiography.

Clin Respir J 2019 Apr 28;13(4):222-231. Epub 2019 Feb 28.

1st Department of Critical Care Medicine and Pulmonary Services, GP Livanos and M Simou Laboratories, Medical School of Athens University, Evangelismos Hospital, Athens, Greece.

Introduction: Impedance cardiography (IC) derived from morphological analysis of the thoracic impedance signal is now commonly used for noninvasive assessment of cardiac output (CO) at rest and during exercise. However, in Chronic Obstructive Pulmonary Disease (COPD), conflicting findings put its accuracy into question.

Objectives: We therefore compared concurrent CO measurements captured by IC (PhysioFlow: CO ) and by the indocyanine green dye dilution method (CO ) in patients with COPD.

Methods: Fifty paired CO measurements were concurrently obtained using the two methods from 10 patients (FEV : 50.5 ± 17.5% predicted) at rest and during cycling at 25%, 50%, 75% and 100% peak work rate.

Results: From rest to peak exercise CO and CO were strongly correlated (r = 0.986, P < 0.001). The mean absolute and percentage differences between CO and CO were 1.08 L/min (limits of agreement (LoA): 0.05-2.11 L/min) and 18 ± 2%, respectively, with IC yielding systematically higher values. Bland-Altman analysis indicated that during exercise only 7 of the 50 paired measurements differed by more than 20%. When data were expressed as changes from rest, correlations and agreement between the two methods remained strong over the entire exercise range (r = 0.974, P < 0.001, with no significant difference: 0.19 L/min; LoA: -0.76 to 1.15 L/min). Oxygen uptake (VO ) and CO were linearly related: r = 0.893 (P < 0.001), CO = 5.94 × VO + 2.27 L/min. Similar results were obtained for VO and CO (r = 0.885, P < 0.001, CO = 6.00 × VO + 3.30 L/min).

Conclusions: These findings suggest that IC provides an acceptable CO measurement from rest to peak cycling exercise in patients with COPD.
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http://dx.doi.org/10.1111/crj.13002DOI Listing
April 2019

Early bursts of disparity and the reorganization of character integration.

Authors:
Peter J Wagner

Proc Biol Sci 2018 11 14;285(1891). Epub 2018 Nov 14.

Department of Earth and Atmospheric Sciences, and School of Biological Sciences, University of Nebraska, Lincoln, NE 20560, USA

'Early bursts' of morphological disparity (i.e. diversity of anatomical types) are common in the fossil record. We typically model such bursts as elevated early rates of independent character change. Developmental theory predicts that modules of linked characters can change together, which would mimic the effects of elevated independent rates on disparity. However, correlated change introducing suboptimal states should encourage breakup (parcellation) of character suites allowing new (or primitive) states to evolve until new suites arise (relinkage). Thus, correlated change-breakup-relinkage presents mechanisms for early bursts followed by constrained evolution. Here, I analyse disparity in 257 published character matrices of fossil taxa. For each clade, I use inverse-modelling to infer most probably rates of independent change given both time-homogeneous and separate 'early versus late' rates. These rates are used to estimate expected disparity given both independent change models. The correlated change-breakup-relinkage model also predicts elevated frequencies of compatible character state-pairs appearing out of order in the fossil record (e.g. 01 appearing after 00 and 11; = low stratigraphic compatibility), as one solution to suboptimal states induced by correlated change is a return to states held before that change. As predicted by the correlated change-breakup-relinkage model, early disparity in the majority of clades both exceeds the expectations of either independent change model and excess early disparity correlates with low stratigraphic compatibility among character-pairs. Although it is possible that other mechanisms for linking characters contribute to these patterns, these results corroborate the idea that reorganization of developmental linkages is often associated with the origin of groups that biologists recognize as new higher taxa and that such reorganization offers a source of new disparity throughout the Phanerozoic.
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http://dx.doi.org/10.1098/rspb.2018.1604DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6253373PMC
November 2018

High ecological complexity in benthic Ediacaran communities.

Nat Ecol Evol 2018 10 17;2(10):1541-1547. Epub 2018 Sep 17.

University of Nebraska-Lincoln, Lincoln, NE, USA.

A long-running debate over the affinities of the Neoproterozoic 'Ediacara biota' has led to contrasting interpretations of Ediacaran ecosystem complexity. A 'simple' model assumes that most, if not all, Ediacaran organisms shared similar basic ecologies. A contrasting 'complex' model suggests that the Ediacara biota more likely represent organisms from a variety of different positions on the eukaryotic tree and thus occupied a wide range of different ecologies. We perform a quantitative test of Ediacaran ecosystem complexity using rank abundance distributions (RADs). We show that the Ediacara biota formed complex-type communities throughout much of their stratigraphic range and thus likely comprised species that competed for different resources and/or created niche for others ('ecosystem engineers'). One possible explanation for this pattern rests in the recent inference of multiple metazoan-style feeding modes among the Ediacara biota; in this scenario, different Ediacaran groups/clades were engaged in different methods of nutrient collection and thus competed for different resources. This result illustrates that the Ediacara biota may not have been as bizarre as it is sometimes suggested, and provides an ecological link with the animal-dominated benthic ecosystems of the Palaeozoic era.
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http://dx.doi.org/10.1038/s41559-018-0663-7DOI Listing
October 2018
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