bluuebunny/crossref_metadata_2025 huggingface dataset:
Determinants of Systematic Risk in the Online Travel Agency Industry
Authors: Lee Won Seok , Moon Joonho , Lee Seoki , Kerstetter Deborah
Published: November 2013

Systematic risk, or the variance of asset returns that cannot be eliminated through diversification of a portfolio, has received limited attention from tourism researchers. This is problematic given the dramatic changes experienced by the industry in the last two decades and the fact that there are unique determinants of systematic risk owing to the tourism industry's idiosyncratic business environment. Therefore, the primary purpose of this study is to identify financial/operating determinants that influence systematic risk for online travel agencies (OTAs). Panel data from 10 US OTA companies listed on the New York Stock Exchange Index from 2001 through 2010 were analysed via a two-way, random-effects model using generalized least squares. The results indicate that advertising expenditures, liquidity and firm size are significant determinants of the systematic risk of OTAs. Appropriate financial/operating management for all three determinants are recommended to decrease that risk. This investigation of OTAs' systematic risk provides practical insights to the OTA industry.
Small particles in distribution systems—The effect of improving treatment
Authors: Byrne Amanda , Braun Kalan , Fabris Rolando , Morran Jim , Drikas Mary
Published: November 2013

Particles originating in water following treatment can create operational and water quality issues in distribution systems. The effect of treated water particle concentration on distribution water quality was assessed by monitoring particles at the beginning and end of four pilot distribution systems (PDSs). Flow conditions in this study produced a 75‐h retention time that included three 8‐h overnight stagnation periods. Generally, higher levels of treatment produced water of lower particle concentration, which resulted in lower particle concentrations and particle volume concentrations in the PDSs. Particles entering the PDS were almost all in the 0.5‐ to 2‐μm size fractions. Deposition and resuspension were found to be the primary mechanisms influencing particle behavior in these systems, with particles lost in systems through deposition and resuspension during flow disturbances. Study results suggest that particle monitoring should be more widely adopted as a management tool and that instruments capable of detecting smaller size fractions should be used.
Des images (et) de Dieu
Authors: Ghilardi Marcello
Published: October 2013

Cet article porte sur l’affinité de pensée entre le maître dominicain Johannes Eckhart (1260-1327) et le philosophe japonais Nishida Kitarō (1870-1945) à propos de la dimension de l’image par rapport au questionnement de ce qui se trouve au-delà de la parole, mais qui demeure comme l’objet central de la recherche théologique et philosophique pour les deux penseurs. L’attitude qui soutient une rencontre entre les pensées de Eckhart et Nishida peut réduire les prétentions absolutistes et identitaires qui empêchent un renouvellement de la philosophie et de la théologie. La vérité qui apparaît dans la rencontre de deux penseurs est une vérité qui reste une, mais pluraliste, puisqu’elle sait respecter la différence des identifications religieuses et philosophiques — il ne s’agit pas de les nier en mêlant tout dans un même système indifférencié — et à la fois elle sait garder un fond qui résiste au-delà ou en deçà des différences.
Loss cone‐driven cyclotron maser instability
Authors: Lee Sang‐Yun , Yi Sibaek , Lim Dayeh , Kim Hee‐Eun , Seough Jungjoon , Yoon Peter H.
Published: October 2013

The weakly (or mildly) relativistic cyclotron maser instability has been successfully applied to explain the Earth's auroral kilometric radiation and other radio sources in nature and laboratory. Among the most important physical parameters that determine the instability criteria is the ratio of plasma‐to‐electron cyclotron frequencies, ωp/Ω. It is therefore instructive to consider how the normalized maximum growth rate, γmax/Ω, varies as a function of ωp/Ω. Although many authors have already discussed this problem, in order to complete the analysis, one must also understand how the radiation emission angle corresponding to the maximum growth, θmax, scales with ωp/Ω, since the propagation angle determines the radiation beaming pattern. Also, the behavior of the frequency corresponding to the maximum growth rate at each harmonic, (ωmax−sΩ)/Ω, where , as a function of ωp/Ωis of importance for a complete understanding of the maser excitation. The present paper computes these additional quantities for the first time, making use of a model loss cone electron distribution function.
Cardiovascular Risk Factors in Women With Primary Sjögren's Syndrome: United Kingdom Primary Sjögren's Syndrome Registry Results
Authors: Juarez M. , Toms T. E. , de Pablo P. , Mitchell S. , Bowman S. , Nightingale P. , Price E. J. , Griffiths B. , Hunter J. , Gupta M. , Bombardieri M. , Sutcliffe N. , Pitzalis C. , Pease C. , Andrews J. , Emery P. , Regan M. , Giles I. , Isenberg D. , Moots R. , Collins K. S. , Ng W. F. , Kitas G. D. ,   on behalf of the UK Primary Sjögren's Syndrome Registry
Published: October 2013

Objective

To determine the prevalence of traditional cardiovascular risk factors using established definitions in a large cohort of clinically well‐characterized primary Sjögren's syndrome (SS) patients and to compare them to healthy controls.

Methods

Data on cardiovascular risk factors in primary SS patients and controls were collected prospectively using a standardized pro forma. Cardiovascular risk factors were defined according to established definitions. The prevalence of cardiovascular risk factors in the primary SS group was determined and compared to that in the control group.

Results

Primary SS patients had a higher prevalence of hypertension (28–50% versus 15.5–25.6%; P < 0.01) and hypertriglyceridemia (21% versus 9.5%; P = 0.002) than age‐ and sex‐matched healthy controls. Furthermore, a significant percentage (56%) of hypertensive patients expected to be on antihypertensive treatment according to best practice was not receiving it.

Conclusion

Primary SS patients are more than 2 times more likely to experience hypertension and hypertriglyceridemia than age‐ and sex‐matched healthy controls. Additionally, hypertension is underdiagnosed and suboptimally treated in primary SS.
Synthesis of acetoxyphenyl‐ and hydroxyphenyl‐terminated polyfunctional T8, T10, T12 silsesquioxanes and initial studies on their use in the formation of highly crosslinked polyesters
Authors: Jung Jae Hwan , Chou Kathleen , Furgal Joseph C. , Laine Richard M.
Published: October 2013

There is continuing interest in the synthesis of polyhydroxy‐terminated molecular species for diverse applications ranging from photolithographic materials to intermediates in the synthesis of porous, crosslinked polymers as media for molecular separations, drug delivery etc. We describe here the use of [vinylSiO1.5]8 and [vinylSiO1.5]10/12 mixtures to synthesize first‐ and second‐generation acetoxyphenyl compounds via metathesis with p‐acetoxystyrene (generation 1, GEN1) or metathesis with p‐bromostyrene followed by Heck coupling with p‐acetoxystyrene (generation 2, GEN2). The resulting acetoxy compounds were then hydrolyzed to produce octa‐, deca‐ and dodecahydroxy GEN1 and GEN2 compounds. These compounds were purified and then reacted with adipic acid chloride to form the first examples of highly crosslinked polyesters based on silsesquioxanes. The coupling products, their hydrolyzed products and the crosslinked polymers were characterized using a variety of spectroscopic methods. In general, the observed specific surface areas were less than 5 m2 g−1; however, the T8 GEN1 derivative gave a surface area of 25 m2 g−1 and was the only crosslinked polymer with a TGA ceramic yield that matched theory for ‘perfect’ crosslinking. This crosslinked polyester has the shortest organic linker between cages and despite the highly flexible C6 linker provides continuing evidence that it is possible to use the cubic symmetry in these materials to build well‐ordered 3‐D nanocomposite structures. Copyright © 2013 John Wiley & Sons, Ltd.
Structure and mechanical properties of novel composites based on glycidyl azide polymer and propargyl‐terminated polybutadiene as potential binder of solid propellant
Authors: Ding Youzhao , Hu Chong , Guo Xiang , Che Yuanyuan , Huang Jin
Published: October 2013

Instead of the traditional isocyanate curing system as the binder of solid propellant, a triazole curing system has been developed by the reaction of azide group and alkynyl group due to a predominant advantage of avoiding to the interference of humidity. In this work, the propargyl‐terminated polybutadiene (PTPB) was blended with glycidyl azide polymers (GAPs) to produce new composites under the catalysis of cuprous chloride at ambient temperature. The triazole‐crosslinked network structure was regulated by changing the molar ratio of azide group in GAP versus alkynyl group in PTPB, and hence various crosslinked densities together with the composition changes of GAP versus PTPB cooperatively determined the mechanical properties of the resultant composites. Furthermore, the formed triazole‐crosslinked network derived from the azide group in GAP and alkynyl group in PTPB resulted in the slight increase of glass transition temperatures and a‐transition temperatures, and improved the miscibility between GAP and PTPB. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40007.
Dual action bactericides: Quaternary ammonium/N‐halamine‐functionalized cellulose fiber
Authors: Hu Bojian , Chen Xiaoqin , Zuo Yan , Liu Zuliang , Xing Xiaodong
Published: October 2013

Bi‐functional antibacterial material was prepared by co‐grafting N‐halamine and quaternary ammonium salt monomers from cellulose fiber. The grafted fiber was characterized by Fourier transform infrared spectra, and X‐ray photoelectron spectra. The N‐halamine derived from the precursor 4‐[(acryloxy)methyl]‐4‐ethyl‐2‐oxazolidinone via chlorination treatment and the oxidative chlorine (Cl+) leaching behavior were investigated. The antibacterial activities of singly (only QAs‐functionalized or only Cl+‐releasing) and dual (QAs‐functionalized and Cl+‐releasing) functional cellulose fibers were tested against Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus. Compared to singly functionalized formulations, the bi‐functional cellulose fiber exhibited excellent and rapid bactericidal performance against both E. coli and S. aureus. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40070.
Fractographic analysis of the crack resistance of styrene–acrylonitrile/polybutadiene‐g‐styrene–acrylonitrile blends as evaluated by the essential work of fracture method
Authors: Mazidi Majid Mehrabi , Razavi Aghjeh Mir Karim , Abbasi Farhang
Published: October 2013

The fracture surfaces and deformation micromechanisms of styrene‐co‐acrylonitrile (SAN)/polybutadiene‐g‐styrene‐co‐acrylonitrile (PB‐g‐SAN) blends with the compositions ranging from 65/35 to 0/100 were studied with a scanning electron microscopy technique. The results were compared to the essential work of fracture parameters obtained in a previous study conducted on double‐edge notched tension specimens. Different plastic damage mechanisms were observed, and they depended on the blend composition. For blends of 65/35 and 45/55, a high degree of rubber particle cavitation and multiple cracking followed by the massive shear yielding of the matrix were found to be the main source of energy dissipation during crack growth. Within this compositional range, more intense plastic damage in a larger volume of material, especially at the notched region, was observed as the concentration of the rubbery phase increased. For the 25/75 blend, the prevailing mechanism was pure shear yielding without any sign of cavitation inside the particles, and the fracture surface became relatively flat and was covered with aligned small microcracks. This sample showed the highest specific essential work (we) value among the blends examined in the previous study. For the samples containing concentrations of dispersed phase higher than 75%, the shear yielding process gradually became less important with the progressive importance of multiple crazing so that high‐magnification micrographs revealed extensive microcracking/crazing both inside and between the rubber particles, as the only active deformation micromechanism for neat PB‐g‐SAN. The variation we and specific plastic work of fracture with the PB‐g‐SAN phase content were successfully explained in terms of prevalent deformation mechanisms. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40072.
Imide‐containing ladder polyphenylsilsesquioxanes with high thermal stability and thermoplastic properties
Authors: Chavez Ricardo , Ionescu Emanuel , Fasel Claudia , Riedel Ralf
Published: October 2013

This work reports for the first time the synthesis of ladder polyphenylsilsesquioxanes containing imide building blocks as parts of the main parallel chains. The ladder structure of the synthesized polymers was documented by means of small angle X‐ray scattering (SAXS) measurements. The obtained ladder polymers exhibit stability with respect to decomposition up to temperatures as high as 460°C; additionally, they have melting points far below their decomposition temperatures, which make them interesting candidate materials for thermoplastic processing. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40085.
Brief Report: Risk of Adverse Fetal Outcomes Associated With Immunosuppressive Medications for Chronic Immune‐Mediated Diseases in Pregnancy
Authors: Cooper William O. , Cheetham T. Craig , Li De‐Kun , Stein C. Michael , Callahan S. Todd , Morgan Thomas M. , Shintani Ayumi K. , Chen Ning , Griffin Marie R. , Ray Wayne A.
Published: October 2013

Objective

To assess the risk of adverse fetal outcomes following exposure to individual immunosuppressive drugs in pregnant women with chronic immune‐mediated diseases.

Methods

Health plan data were obtained from the Tennessee Medicaid and Kaiser Permanente Northern California and Southern California claims databases, with linkage to both vital records and medical records. Women with inflammatory arthropathies, those with systemic lupus erythematosus, and those with inflammatory bowel disease who filled prescriptions for immunosuppressive treatments during pregnancy were included. Major congenital malformations, fetal deaths, and life‐threatening neonatal complications were identified from the electronic data and validated with medical record review.

Results

The cohort included 608 infants, including 437 with exposure to immunosuppressive drugs during the mother's pregnancy (402 during the first trimester, and 35 during the second and third trimester only) and 171 whose mothers filled prescriptions for immunosuppressive treatments before, but not during, pregnancy. There were 25 pregnancies (4.1% of the cohort) with confirmed major congenital malformations, and 10 fetal deaths (1.6% of the cohort). Among 113 preterm infants with exposures during pregnancy, 23 (20.4%) had life‐threatening neonatal complications, and among 485 term infants, 10 (2.1%) had life‐threatening complications. Compared to the reference group (treatment before, but not during, pregnancy), the risk ratios (RRs) for adverse fetal outcomes associated with immunosuppressive treatments (by exposure category) during pregnancy included the following: methotrexate (RR 1.39, 95% confidence interval [95% CI] 0.43–4.53), tumor necrosis factor inhibitors (RR 0.98, 95% CI 0.38–2.55), hydroxychloroquine (RR 1.33, 95% CI 0.69–2.55), and other immunosuppressive medications (RR 0.98, 95% CI 0.48–1.98).

Conclusion

In this study, there was no evidence of a large increase in risk of adverse fetal outcomes from first‐trimester exposure to immunosuppressive medications, although the confidence intervals for the risk ratios were wide. Further studies will be needed as use of these medications increases over time.
A magnetic nanobead‐based bioassay provides sensitive detection of single‐ and biplex bacterial DNA using a portable AC susceptometer
Authors: Strömberg Mattias , Zardán Gómez de la Torre Teresa , Nilsson Mats , Svedlindh Peter , Strømme Maria
Published: October 2013

Bioassays relying on magnetic read‐out using probe‐tagged magnetic nanobeads are potential platforms for low‐cost biodiagnostic devices for pathogen detection. For optimal assay performance it is crucial to apply an easy, efficient and robust bead‐probe conjugation protocol. In this paper, sensitive (1.5 pM) singleplex detection of bacterial DNA sequences is demonstrated in a portable AC susceptometer by a magnetic nanobead‐based bioassay principle; the volume‐amplified magnetic nanobead detection assay (VAM‐NDA). Two bead sizes, 100 and 250 nm, are investigated along with a highly efficient, rapid, robust, and stable conjugation chemistry relying on the avidin–biotin interaction for bead‐probe attachment. Avidin‐biotin conjugation gives easy control of the number of detection probes per bead; thus allowing for systematic investigation of the impact of varying the detection probe surface coverage upon bead immobilization in rolling circle amplified DNA‐coils. The existence of an optimal surface coverage is discussed. Biplex VAM‐NDA detection is for the first time demonstrated in the susceptometer: Semi‐quantitative results are obtained and it is concluded that the concentration of DNA‐coils in the incubation volume is of crucial importance for target quantification. The present findings bring the development of commercial biodiagnostic devices relying on the VAM–NDA further towards implementation in point‐of‐care and outpatient settings.
A novel technique for catheter engagement of protruding aorto‐ostial stent
Authors: Uehara Yoshiki , Shimizu Mitsuyuki , Yoshimura Michihiro
Published: October 2013

We present a case of stenoses in the right coronary artery with a previously deployed stent showing gross protrusion into the aorta. Despite difficulty in cannulation of a guiding catheter into the coronary artery, percutaneous intervention was accomplished using a novel technique to engage the protruding stent. © 2013 Wiley Periodicals, Inc.
Procedural variation in the performance of primary percutaneous coronary intervention for ST‐elevation myocardial infarction: A SCAI‐based survey study of US interventional cardiologists
Authors: Chiang Austin , Gada Hemal , Kodali Susheel K. , Lee Michael S. , Jeremias Allen , Pinto Duane S. , Bangalore Sripal , Yeh Robert W. , Henry Timothy D. , Lopez‐Cruz Georgina , Mehran Roxana , Kirtane Ajay J.
Published: October 2013

Background

Great strides have been made in improving outcomes for patients with ST‐elevation myocardial infarction (STEMI), predominately through initiatives focusing upon improving clinical processes “upstream” of percutaneous coronary intervention (PCI). The actual step‐by‐step mechanics of diagnostic angiography during STEMI and other aspects of the PCI procedure itself have received relatively little attention.

Objectives and Methods

We hypothesized that there would be significant variation in how primary PCI for STEMI is performed in the United States. In order to better understand current US practice, an electronic survey consisting of seven focused questions was forwarded to 2,910 US interventional cardiologists who were members of the Society for Cardiovascular Angiography and Interventions (SCAI).

Results

Three hundred sixty‐two responses were received (12.4%). Among respondents, the femoral artery was the preferred access site in 83% (vs. 17% radial). The use of a diagnostic catheter to visualize the non‐culprit artery prior to using a guiding catheter for the culprit artery was the preferred approach for 58% of respondents, and an additional 23% preferred complete angiography with diagnostic catheters prior to guide insertion. However, a significant minority (19%) preferred starting directly with a guide catheter for the culprit artery and performing PCI prior to contralateral non‐culprit artery visualization. Only 9% reported performing routine left ventriculography prior to PCI, with the majority (66%) choosing to perform ventriculography during/after PCI, and 25% reporting rare or no use of left ventriculography. Fewer than half of respondents (49%) reported routine aspiration thrombectomy use, despite a Class IIa ACC/AHA guidelines recommendation.

Conclusions

There is significant variability in the self‐reported mechanics of primary PCI by US interventional cardiologists. Some of this variability (e.g., sequence of catheters, and performance of left ventriculography prior to reperfusion) is not addressed by current guidelines/consensus documents, and may have clinical implications, reflecting the balance between the desire for timely reperfusion versus a more complete assessment of patient risk. © 2013 Wiley Periodicals, Inc.
Optimizing rotational atherectomy in high‐risk percutaneous coronary interventions: Insights from the PROTECT ΙΙ study
Authors: Cohen Mauricio G. , Ghatak Abhijit , Kleiman Neal S. , Naidu Srihari S. , Massaro Joseph M. , Kirtane Ajay J. , Moses Jeffrey , Magnus Ohman E. , Džavík Vladimír , Palacios Igor F. , Heldman Alan W. , Popma Jeffrey J. , O'Neill William W.
Published: October 2013

Objective

To study rotational atherectomy (RA) outcomes in patients undergoing high‐risk PCI randomized to receive hemodynamic support using either IABP or Impella 2.5 in the PROTECT II trial.

Background

RA of heavily calcified lesions is often necessary for complex PCI but can be associated with slow‐flow, hypotension, and higher risk of periprocedural MI.

Methods

We compared baseline, angiographic, procedural characteristics, and outcomes of patients treated with and without RA. We examined also RA technique and outcomes.

Results

RA was used in 52 of 448 patients (32 with Impella vs 20 with IABP, P = 0.08). RA patients were older (72 vs. 67 yo, P = 0.0009), more likely to have prior CABG (48 vs. 32%, P = 0.017), higher STS (8.1 vs. 5.7, P = 0.012) and higher SYNTAX scores (37 vs. 29, P < 0.0001). At 90 days, RA use was associated with higher incidence of MI but no mortality difference. RA was used more aggressively with Impella resulting in higher rate of periprocedural MI (P < 0.01), with no difference in mortality between groups (P = 0.78). Repeat revascularization occurred less frequently with Impella (P < 0.001). There were no differences in 90‐day major adverse events between IABP and Impella in patients undergoing RA (P = 0.29). In patients not treated with RA, fewer MAEs were observed with Impella compared with IABP (P = 0.03).

Conclusions

Patients who were treated with RA had more comorbidities, and more complex and extensive coronary artery disease. In patients with Impella, more aggressive RA use resulted in fewer revascularization events but higher incidence of periprocedural MI. © 2013 Wiley Periodicals, Inc.
Complications related to transhepatic venous access in the catheterization laboratory—A single center 12‐year experience of 124 procedures
Authors: Qureshi Athar M. , Prieto Lourdes R. , Bradley‐Skelton Sharon , Latson Larry A.
Published: October 2013

Objectives

To identify complications and measures that can be undertaken to prevent complications from transhepatic central venous access.

Background

Utility and safety data from a large experience of patients undergoing transhepatic venous access are lacking.

Methods

The records of patients who underwent transhepatic venous access between June 2000 and October 2012 at The Center for Pediatric and Congenital Heart Disease at The Cleveland Clinic were reviewed.

Results

One hundred twenty‐four transhepatic procedures were performed in 81 patients. The median weight of the patients was 6.3 (2.2–94) kg at a median age of 7 months (2 weeks to 35 years). Diagnostic catheterizations were performed in 75, interventions in 39, and central venous line placement in 91 procedures. The median maximum sheath size inserted was 8 (4–14) French. There were 10 (8%) major adverse events in 8 procedures—bleeding related (n = 6 with 1 death as a result) or complete heart block with instability or requiring intervention (n = 4). Heart block persisted after the catheterization in three patients (2 days, 2 weeks, 1 month). Minor adverse events (transient heart block) occurred in 5 (4 %) procedures. Weight, age, and French size of sheath (P = 0.46, 0.84, and 0.18) were not associated with complications. In addition, time to gain access was not different between non‐complicated and complicated cases (median 19.5 versus 15.1 min, P = 0.72). Diagnostic and interventional procedures were not associated with more complications compared with procedures involving central venous line placement alone (P = 0.5).

Conclusions

Transhepatic access is an extremely useful modality of access to the heart and vascular structures in some patients with complex heart disease. Prevention of complications should focus on minimizing bleeding risks and heart block. © 2013 Wiley Periodicals, Inc.
Silanol‐Assisted Aldol Condensation on Aminated Silica: Understanding the Arrangement of Functional Groups
Authors: Lauwaert Jeroen , De Canck Els , Esquivel Dolores , Thybaut Joris W. , Van Der Voort Pascal , Marin Guy B.
Published: October 2013

Free silanol groups are known to promote the activity of aminated silica. In this work the effect of the silanol‐to‐amine ratio on the aldol condensation of 4‐nitrobenzaldehyde and acetone is investigated in a range from 0 to 2.4. Irrespective of the amine density, identical, moderate turnover frequencies are obtained if the silica exclusively has amines on its surface. The turnover frequency increases with increasing silanol‐to‐amine ratio until an upper limit is reached at a silanol‐to‐amine ratio of 1.7. At this upper limit the turnover frequency is a factor 5 higher than the turnover frequencies obtained with the monofunctional amine‐based catalysts. This increase is ascribed to hydrogen‐bridge interactions between the silanols and the carbonyl moiety of the reactants that provoke a more easy interaction between the carbonyl moiety and the amine as required for the aldol condensation. The observation that higher values than one for the silanol‐to‐amine ratio are required is rationalized by computer simulations. It was found that amine groups were grafted on the silica surface in a clustered manner, originating from positive deviations from ideality in the synthesis mixture, that is, from clustering of the amine precursor in the liquid phase.
Explosion Protection by Steam Inertization: Minimizing Emissions
Authors: Bierbaum Ralf , Franke Jürgen , Westphal Frank
Published: October 2013

Die Inertisierung von chemischen Reaktoren, in denen brennbare organische Stoffe eingesetzt werden, erfolgt in der Regel mit Inertgasen wie Stickstoff. Die Inertisierung mit Wasserdampf ist ebenfalls möglich, aber auf Systeme beschränkt, in denen Wasser auch als Betriebsmedium vorliegt. Zudem sind die Einstellung einer gleichmäßigen Verteilung im System und die Vermeidung von Kondensation schwieriger. Es wird ein Anwendungsfall für eine Wasserdampf‐Inertisierung beschrieben, die neben Kosteneinsparungen vor allem auch zu deutlich geringeren Emissionen des organischen Lösemittels führt. Dabei werden auch die phlegmatisierenden Eigenschaften des Wasserdampfs genutzt, die u. a. zu höheren Sauerstoffgrenzkonzentrationen führen als beim Einsatz von Stickstoff.
Studies on the regulation of myocardial blood flow in man II. Effects of acute arterial hypoxia
Authors: Heiss H. W. , Töpfer M. , Barmeyer J. , Wink K. , Huber G. , Keul J.
Published: October 2013

To determine whether adjustment of myocardial blood flow (MBF), myocardial oxygen consumption (MVO2) and myocardial substrate uptake (MSU) to acute arterial hypoxia is influenced by training effects on the heart, 7 trained and 7 untrained healthy individuals were investigated. MBF (argon method), MVO2 and MSU of glucose, lactate and free fatty acids were measured at rest during normoxia and two different stages of acute arterial hypoxia: a) 12.82 vol% O2; b) 8.74 vol% O2. Measurements were carried out during hemodynamic and respiratory steady state conditions.

Myocardial flow and metabolism of athletes were significantly (p<0.01) lower compared to untrained subjects. In the trained cohort, MBF increased from 65 ± 19 to 73 ± 16 (a) and 98 ± 23 (b) ml/min·100 g. MVO2 remained at normoxic control level of 8.00 ± 2.27 ml/min·100g. In the untrained group, MBF increased from 77 ± 15 to 84 ± 20 (a) and 108 ± 18 (b) ml/min · 100g. Again, there was no significant deviation in MVO2 from the normoxic level of 10.11 ± 1.90 ml/min·100g. Decrease in arterial oxygen content was overcompensated by an increase in coronary conductance resulting in a significantly improved efficiency of myocardial perfusion during severe hypoxia. MSU of glucose, lactate and free fatty acids as well as calculated ATP production did not change significantly during hypoxia.

It is concluded that training effects on the heart do not influence regulation of MBF, MVO2 and MSU during moderate or severe acute arterial hypoxia. Reaction of coronary smooth muscle tone to a decrease in oxygen partial pressure is independent from training effects. However, both acute arterial hypoxia and physical training exert synergetic effects on the heart by reducing myocardial oxygen consumption per heart beat. Thus, it is assumed that adaptive properties of myocardial blood flow and metaboüsm to severe hypoxia are more pronounced in trained than in untrained individuals.
Persistent atrial standstill developed in a patient with rheumatic heart disease: Electrophysiological and histological study
Authors: Yoneda S. , Murata M. , Ueda A. , Sato M. , Takahashi M. , Ito T. , Sada T. , Matsumoto S. , Ito Y. , Furuta S. , Kamiyama A. , Akaike A.
Published: October 2013

A case with persistent atrial standstill is presented which developed from atrial fibrillation associated with rheumatic combined valvular heart disease. In addition to clinical and electrocardiographic findings, electrophysiological and histological studies by using microelectrode technique and electron microscopy, respectively, were carried out on specimens from the right atrial appendage resected at mitral valve surgery.

Scattered but severe loss of myocardial cells in the atria and deterioration of the action potential of these poorly sustained myocardial cells were confirmed. The suggestive evidence is also shown that the deteriorated action potential observed by micro‐electrode technique in this case may be composed of calcium current.
Myocardial imaging with extractable cations and inert tracers: The effects of flow and metabolism
Authors: Selwyn A. P. , Fox K. , Shillingford J. P.
Published: October 2013

The physical and biological properties of 201thallium (Tl) have been investigated and are discussed in this review.

A new technique using the ultra‐short lived 81mkrypton (81mKr) as a continuous infusion into the aortic root in dogs and man is described. This provides a dynamic assessment of changes in regional myocardial perfusion. Experiments using 201Tl and 81mKr in dogs have shown that regional decreases in myocardial perfusion alone cannot be detected in images of the heart using 201Tl. The effects of perfusion and a variety of factors on the energy dependent cellular uptake of 201Tl are discussed as being of primary importance in changing the regional myocardial distribution of this tracer.

The constant infusion of 81mKr in patients with anginal chest pain provides continuous measurement of regional myocardial perfusion in high spatial resolution images. This dynamic method provides a physiological assessment of stenosed coronary arteries at rest and during stress.
Non‐parenteral combined afterload and preload reduction therapy in congestive heart failure
Authors: Mehta J. , Pepine C. J. , Conti C. R. , Sollaway R. H.
Published: October 2013

It has been shown that hydralazine is beneficial in chronic heart failure by virtue of its afterload reducing effect. Nitroglycerin paste results in venodilation and fall in left ventricular filling pressure (LVFP). Thirteen patients with chronic heart failure were given a combination of oral hydralazine and nitroglycerin paste. With oral hydralazine (75 to 100 mg every 8 h), left ventricular stroke work increased and LVFP slightly fell. Following addition of 2% nitroglycerin paste, an additional decline in mean pulmonary artery and LVFP was observed without significant changes in heart rate and arterial pressure. There were no untoward side effects from either therapy. Eight patients followed for three to eight months (mean five months) reported subjective improvement in shortness of breath and other symptoms related to ventricular dysfunction. This study shows that in certain patients with chronic heart failure, hydralazine and nitroglycerin paste combination produces salutary clinical effects on long term probably through afterload and preload reduction, respectively.
The role of cross‐sectional echocardiography in the diagnosis of flail mitral leaflet
Authors: Ogawa S. , Mardelli T. J. , Hubbard F. E. , Meixell L. , Dreifus Leonard S.
Published: October 2013

Cross‐sectional echocardiography was performed on two patients with mitral regurgitation in whom M‐mode echocardiographic findings were not specific for the etiology of mitral regurgitation. In one patient, flail motion of the free edge of the anterior mitral leaflet into the left atrium was demonstrated only by cross‐sectional echocardiograms. In the second patient, the flail posterior mitral leaflet was suggested to be a result of bacterial endocarditis. Cross‐sectional echocardiograms clearly identified a flail motion of a mass of vegetation attached to the posterior mitral leaflet.

Thus, cross‐sectional echocardiography can provide critical information in recognizing patients with a flail mitral leaflet.
Differences in platelet aggregation in coronary sinus and aortic blood in patients with coronary artery disease: Effect of propranolol
Authors: Mehta J. , Mehta P. , Pepine C. J. , Burger C.
Published: October 2013

Platelet aggregation was studied in aortic and coronary sinus blood samples obtained from 18 patients with coronary artery disease (CAD). Using epinephrine and ADP as aggregating agents, platelet aggregation was lower in coronary venous blood than in aortic blood. In nine patients on long‐term propranolol therapy, platelet aggregation was lower in both aortic and coronary venous blood compared to the nine patients not taking propranolol. Four other subjects without angiographic evidence of coronary disease exhibited no difference in platelet aggregation in aortic and coronary sinus blood. These data suggest that platelet aggregation is lower in the coronary venous blood of certain patients with coronary disease and chronic propranolol treatment may reduce aggregation in both aortic and coronary sinus blood.
Acute coronary occlusion with impending infarction as an angiographic complication relieved by a guide‐wire recanalization
Authors: Rentrop P. , de Vivie E. R. , Karsch K. R. , Kreuzer H.
Published: October 2013

In a 45 year old male patient with a history of previous inferior myocardial infarction and unstable angina pectoris, coronary angiography revealed two‐vessel disease: a 60‐70% lesion in the middle third of the LAD, and a 90% lesion in the middle third of the very large RCA. There was only a small akinetic segment in the posterobasal region of the left ventricle. During angiography total occlusion of the RCA occurred, followed by clinical and electrocardiographic signs of impending inferior reinfarction.

Recanalization of the occluded vessel was accomplished by using a guide‐wire, which was passed through a Sones catheter, placed in the RCA. The patient's symptoms subsided and the electrocardiographic signs of acute ischemia reverted within eight minutes.

Aortocoronary bypass surgery with revascularization of the LAD and RCA was performed within 3 hours after recanalization. Postoperatively there was no evidence of major tissue loss by enzyme or electrocardiographic criteria. Control angiography, performed on the ninth day postoperatively, revealed the graft to the RCA to be widely patent. Left ventricular function was unchanged.

It is concluded, that the combined approach of early transluminal recanalization of the acutely occluded RCA, followed by successful construction of a graft to this vessel, has averted necrosis of a major portion of the left ventricle. However, general use of this technique does not seem advisable at the present time.
Therapeutic implications of the use of selective beta‐adrenoceptor antagonists in clinical cardiology — A current review
Authors: Comerford M. B.
Published: October 2013

During the last five years of the beta‐blocker era, there has been a slow but steadily increasing interest in the clinical aspects of the selective compounds. A critical appraisal of the works published in the various fields of angina, hypertension, metabolic disorders, respiratory function, stress and exercise responses, suggests a therapeutic progress worthy of the clinician's attention.
Initial experience with transluminal recanalization of the recently occluded infarct‐related coronary artery in acute myocardial infarction — Comparison with conventionally treated patients
Authors: Rentrop K. P. , Blanke H. , Karsch K. R. , Kreuzer H.
Published: October 2013

In 7 patients, the recently occluded infarct‐related vessel was recanalized by transluminal catheter techniques during acute myocardial infarction (Group A). 4 patients had single‐vessel disease, 2 patients two‐vessels disease and one, involvement of three vessels. Control angiography was performed in 6 patients, 8 days to 7 months later. Changes of coronary artery anatomy and left ventricular function were compared with a group of 9 conventionally treated patients, who were found to have occlusion of the infarct‐related vessel in the acute stage (Group B). Five Group B patients had one‐vessel disease, 3 patients two‐vessel disease and 1 patient, involvement of all three vessels. In the chronic stage, all transluminally recanalized vessels were found to be patent in Group A. There was spontaneous recanalization of the infarct vessel in 4 of 9 Group B patients. In Group A, the length of the akinetic segment (AKS) decreased significantly (p < 0.05) from 145.4±48.5 mm to 73.2 ± 73.4 mm (mean ± SD). Volume parameters did not change significantly. In Group B, length of the AKS did not change significantly, EDVI increased significantly from 81.1 ±19.8 to 106.8±40.6 ml/m2 (p < 0.05); ESVI increased significantly from 41.7 ± 13.7 ml/m2 to 66.8 ± 37.9 ml/m2 (p < 0.01). In the acute stage, length of the AKS and volume parameters did not differ significantly between the two groups. In the chronic stage, AKS was significantly shorter (A: 73.2 ± 63.4 mm; 144.9 ± 59 mm (p < 0.0025)) and EF was significantly higher (A: 54.6 ±11.6%; B: 40.9 ±14.5% (p < 0.05)) in Group A. Peak CPK was lower in Group A (A: 1009 ± 827 U/l; B: 1324 ± 655 U/l), but this difference did not achieve statistical significance. Results of this pilot study suggest that transluminal recanalization in the early phases of acute myocardial infarction might result in limitation of myocardial injury. However, further research will be needed to improve the technique and to test its results.
Nitroglycerin in acute myocardial infarction X. Effect of small and large doses of nitroglycerin on sigma ST segment deviation — Experimental and clinical results
Authors: Bussmann W.‐D. , Schöfer H. , Kurita A. , Ganz W.
Published: October 2013

The purpose of the present study was to investigate the effect of the dose of nitroglycerin (NTG) on myocardial ischemic injury. In 20 closed chest dogs the anterior descending branch of the left coronary artery was occluded by inflating a balloon in its lumen. Compared with the untreated control group the Z ST elevation was significantly lower when NTG was applied at a rate of 0.02 mg/min, but significantly higher when NTG was administered at a rate of 0.10 mg/min. In 12 patients with acute myocardial infarction NTG was infused at a rate of 3 mg in the first hour (0.05 mg/min) and 6 mg in the second hour (0.1 mg/min). Σ ST elevation and Σ ST depression decreased during the lower infusion rate (p < 0.001). When the rate of NTG infusion was raised to 6 mg/hr, the improvement in ST segment deviation was partially reversed. This effect, particularly evident in patients not in heart failure, was associated with a significant rise in heart rate (p < 0.05) and a fall in diastolic arterial pressure (p < 0.025). Patients with left ventricular failure were less sensitive to higher doses of NTG than those without failure. Thus, the effect of NTG on myocardial ischemic injury depends on the NTG dose and on the functional state of the injured left ventricle.
Dimeditiapramine (Ro 11‐1781), a new calcium antagonist, in the management of supraventricular tachyarrhythmias in patients with acute myocardial infarction
Authors: Cocco G. , Chu D. , Strozzi C.
Published: October 2013

18 patients with acute myocardial infarction and sustained arrhythmias were treated with a new Ca2+ antagonist, Ro 11‐1781, at the dose of 1.0 mg/kg i.v. The drug was effective in reducing heart rate to less than 90 beats/min in 9/10 patients with atrial fibrillation, in 3/4 patients with atrial flutter and in 3/4 patients with supraventricular tachycardia. The peak effect was observed within 2‐5 min after the intravenous administration of Ro 11‐1781. In cases with recurring tachyarrhythmias, the drug was also effective in repetitive administration. Systolic blood pressure was reduced, but severe hypotension (< 90 mm Hg) was not observed. The atrioventricular conduction in these patients remained unimpaired and asystole did not occur. The drug appears to be an effective and a well tolerated antiarrhythmic agent.
A double‐blind trial of disopyramide, procaineamide and digoxin in paroxysmal supraventricular tachycardia
Authors: Craig M. W. Millar , Raftery E. B.
Published: October 2013

A double‐blind cross‐over study has been performed in 10 patients with an established diagnosis of paroxysmal supraventricular tachycardia to compare the effectiveness of three active agents with placebo. The drugs were administered in random sequence for two‐week periods with three‐day washout intervals and in standard dose regimes as recommended for prophylaxis by authoritative works on the subject. The results suggest that digoxin is ineffective at the recommended dosage. Procaineamide was effective in controlling some arrhythmias, but disopyramide was the most effective agent studied. All these patients showed a mixture of arrhythmias, and also had a lot of ectopic activity. Arrhythmic activity is erratic and unpredictable, and a larger number of patients would need to be studied for long periods of time to obtain enough data for valid statistical assessment.
Myocardial imaging with 134mCesium. Comparison of scintigraphic and cineradiographic results
Authors: Eybel C. E. , Turner D. A. , Rayudu G. V. S. , Fordham E. W. , Friedman A. M. , Messer J. V.
Published: October 2013

Thirty‐four patients had noninvasive myocardial perfusion imaging at rest using 134mCs. The results were compared with the results of coronary cineangiography and left ventriculography. All 21 patients who had abnormal left ventriculograms had corresponding myocardial imaging defects. This group included 14 patients with electrocardiographic evidence of either an old inferior, anteroseptal, anterior, or anterolateral myocardial infarction. Thirteen patients had normal left ventriculograms: this group included 6 patients with 75% or greater obstruction of one or more coronary arteries and 7 patients with normal or insignificantly diseased vessels. Only 2 of these patients had abnormal myocardial images: both had severe obstruction of the proximal left anterior descending artery without collateral filling of this vessel. In the resting patient who has 134mCs myocardial imaging, we concluded that we primarily are visualizing varying degrees of scarred myocardium rather than reversibly ischemic myocardium.
Antianginal efficiency of nifedipine with and without a beta‐blocker, studied with exercise test. A double‐blind, randomized subacute study
Authors: Ekelund L.‐G. , Orö L.
Published: October 2013

Twenty‐one patients, mean age 60.3 years, with stable angina pectoris earlier treated with beta‐blockers, were investigated with standardized exercise tests to evaluate the action of nifedipine alone and in combination with a beta‐blocker. The first exercise test was performed 3 weeks after treatment with the patient's usual beta‐blocker. Following this, the patients were tested twice after a double‐blind cross‐over 3‐week trial with nifedipine and placebo. The patients were subsequently treated for 3 weeks with nifedipine 10 mg 3 times daily or placebo and then performed an exercise test. During the 4th period of 3 weeks the patients took a combination of nifedipine, 10 mg 3 times daily, and their usual beta‐blocker and then performed the final exercise test.

Nifedipine alone raised the heart rate by 5 beats/min at rest and diminished the systolic blood pressure at rest by 17 mm Hg. During exercise at comparable load the heart rate did not change significantly, but the systolic blood pressure decreased with 22 mm Hg. The exercise tolerance expressed as total work increased on an average by 20%, range −14 — +194%. Nifedipine in combination with a beta‐blocker gave a further decrease in the systolic blood pressure, totally 37 mm Hg at comparable load. The exercise tolerance increased more, totally by an average of 41%. There was a significant correlation between basal values for systolic blood pressure registered during the placebo period at rest and the percentage change in total work. The atrioventricular conduction time did not change significantly compared to placebo during treatment with nifedipine or the combination nifedipine + beta‐blocker. No serious side‐effects were observed during the study.