bluuebunny/crossref_metadata_2025_split huggingface dataset:
β‐Ca3N2, a Metastable Nitride in the System Ca–N
Authors: Höhn Peter , Hoffmann Stefan , Hunger Jens , Leoni Stefano , Nitsche Fabian , Schnelle Walter , Kniep Rüdiger 
Published: February 2009

AbstractA new page in the phase book: The metastable nitride β‐Ca3N2, the synthesis, crystal structure (see picture), and physical properties of which are reported, is an isotype of corundum (α‐Al2O3). Vacancies in the crystal structure of β‐Ca3N2 are discussed by using full‐potential local orbital methods and taking into account both the physical properties and the density of states.magnified imageThe structural chemistry of calcium nitrides is represented by just two different intermediate phases: cubic Ca3N2 (referred to as α‐Ca3N2, Mn2O3 type structure) and Ca2N (CdCl2 type structure). Other binary phases (“γ‐Ca3N2”, “Ca11N8”) have been proven to represent cyanamide nitrides, Ca4N2[CN2] and Ca11N6[CN2]2, respectively. The metastable nitride β‐Ca3N2 is prepared either by reaction of freshly distilled calcium metal with nitrogen at 700 K, or by reaction of Ca2N with N2 at 500 K. β‐Ca3N2 transforms monotropically (Ttrans≈810 K) to cubic α‐Ca3N2. The crystal structure of β‐Ca3N2 (rhombohedral R$\bar 3$c, no. 167, a=619.884(3) pm, c=1662.958(10) pm) is an isotype of the corundum structure (α‐Al2O3) and comprises a network of NCa6/4 octahedra that share common faces and edges. Magnetic susceptibility and electrical resistivity measurements confirm that β‐Ca3N2 is a diamagnetic semiconductor.
Alkali Metal Cation (K+, Cs+) Induced Dissolution/Reorganization of Porous Metal Carboxylate Coordination Networks in Water
Authors: Wu Jing‐Yun , Ding Miao‐Tzu , Wen Yuh‐Sheng , Liu Yen‐Hsiang , Lu Kuang‐Lieh 
Published: February 2009

AbstractReversible structural transformations of porous metal–organic coordination networks based on Co or Ni and the benzene‐1,2,4,5‐tetracarboxylate tetraanion among 3D (4,8)‐connected nets and a 1D zigzag chain structure occur by an unexpected dissolution/reorganization process induced by alkali metal cations (K+, Cs+) in aqueous solution (see scheme).magnified imagePorous metal–organic coordination networks (MOCNs) {A2[M3(btec)2(H2O)4]}n (1, A=K, M=Co; 2, A=K, M=Ni; 3, A=Cs, M=Co; and 4, A=Cs, M=Ni; btec=benzene‐1,2,4,5‐tetracarboxylate) with nearly identical structural features were hydrothermally prepared. These compounds adopt (4,8)‐connected scu nets but exhibit subtle differences in the topology of the final three‐dimensional architectures. Compound 1 has a regular net with the largest solvent void (21.1 %), while the nets of the other three (2–4) are slightly distorted from a regular shape and have malformed pores with smaller solvent voids (5.4–11.4 %). Likely, the different supramolecular environments among 1–4 subtly depend on the eight‐connected binodal cubical vertices/four‐connected square‐planar connectivity between the trimetallic clusters and the btec ligands. Cobalt species 3 dissolved in an aqueous solution of KCl, and then reorganized to form 1 at ambient temperature. Interestingly, under similar conditions, 1 dissolved and then was regenerated to give the same structure. Nickel species 2 and 4 also underwent a dissolution/reorganization process in an aqueous solution of KCl to afford new metal–carboxylate product {K2[Ni3(btec)2(H2O)4]}n (2′). This compound forms a (4,8)‐connected scu net with regular pores, which is isostructural and isomorphous with 1, and is a supramolecular isomer of 2. Similarly, in an aqueous solution of CsCl, 1–4 were converted to 1D zigzag chain structures {Cs2[M(btec)(H2O)4]}n (5, M=Co; 6, M=Ni) that enlarged to hydrogen‐bonded 3D porous supramolecular networks. Remarkable, reversible alkali metal cation induced structural transformations between 1 and 5 occurred via dissolution/reorganization processes. Thermogravimetric analyses showed that these metal–carboxylate species have high thermal stability (T>300 °C).
Highly Enantioselective 1,4‐Addition of Diethyl Phosphite to Enones Using a Dinuclear Zn Catalyst
Authors: Zhao Depeng , Yuan Ye , Chan Albert S. C. , Wang Rui 
Published: February 2009

AbstractZinc benefits: The first catalytic asymmetric phospha‐Michael addition of enones has been developed. Under mild reaction conditions, the γ‐oxo phosphonates could be obtained in high yields (up to 99 %) with excellent enantioselectivities (93–99 % ee; see scheme). The strategy makes the asymmetric synthesis of biologically important phosphonate compounds more accessible.magnified image
Recent advances using streptokinase for acute coronary thrombosis
Authors: Udall J. A. 
Published: February 2009

AbstractMost important in comparison to earlier European trials, streptokinase (STK) is administered now at the earliest time possible after acute coronary thrombosis. In this series, STK was started 2.5 (±1.5) h after onset of chest pain, with reperfusion achieved approximately 1h later in 6 (55%) of 11 patients treated. Posttreatment angiograms will not be required to identify thrombolysis if noninvasive indicators will prvoide this information correctly. Early creatine kinase enzyme peaking 8 to 15 h after chest pain appears to be the most accurate marker available. Among untreated and unsuccessfully treated patients, creatine kinase peaking usually occurs 18‐36h after chest pain. A large intravenous STK loading dose of 1,500,000 IU produces a plasma concentration of approximately 500 IU/ml, equal to that concentration employed originally by intracoronary infusions. Such large doses have been employed in 60 patients thus far, without an unusual incidence or severity of hemorrhages. High dose, ultrashort‐term treatment for only 1 h is being investigated now. Systemic STK penetrates most “blind coronary pouches” and gains access to acute thrombi, as identified by radiocontrast material washout during angiography in patients with severe coronary occlusions. Streptokinase exerts a significant anticoagulant effect, not previous considered, which may be beneficial in the prevention of new clot formation and the rapid dissolution of acute coronary thrombi.
Effect of intra‐aortic balloon pumping on left ventricular function: Evaluation by radionuclide ventriculography
Authors: Iskandrian A. S. , Colby J. , Hakki A‐H. , Boston B. , Kane S. A. 
Published: February 2009

AbstractThe purpose of this study was to evaluate the effect of intra‐aortic balloon pumping (IABP) on left ventricular (LV) performance in ten patients (group I) with pump failure and in ten patients (group II) with angina pectoris. Left ventricular ejection fraction, regional ejection fraction, systolic chordal shortening and volumes were measured by first‐pass radionuclide ventriculography using a computerized multicrystal gamma camera. Patients in group I had significantly lower ejection fractions, regional ejection fractions and systolic chordal shortening and larger end‐diastolic and end‐systolic volumes than patients in group II, both on (p>0.0001) and off (p<0.004) IABP. With IABP, the ejection fraction increased by 0±0.5% in group I and 5.8±1.7% in group II (p=0.004); the regional ejection fraction increased by 0.1 ±0.9% in group I and 10.3±2.1% in group II (p=0.0004); the systolic chordal shortening increased by 1.1 ±0.6% in group I and 6.5 ±1.1% in group II (p=0.0006); the end‐diastolic volume decreased by ‐0.4±6% in group I and 14±4% in group II (p=0.07); and the end‐systolic volume decreased by ‐1±6% in group I and ‐21 ±5% in group II (p=0.02). Thus, IABP results in improvement in left ventricular performance in patients with angina pectoris but not in patients with pump failure.
Isolated left posterior fascicular block associated with acquired ventricular septal Defect
Authors: Rokey R. , Chahine R. A. 
Published: February 2009

AbstractIsolated left posterior fascicular block in the absence of associated right bundle‐branch block is a rare electrocardiograpic finding. In view of its anatomy and the fact that it receives a dual blood supply, the posterior fascicle of the left bundle branch appears to be less vulnerable than the anterior fascicle or the right bundle. Mechanical disruption of the posterior fascicle can produce isolated left posterior fascicular block. This has been demonstrated in animal models. However, such oc‐curence has not been noted in humans. We present two cases of inferior wall myocardial infarction, complicated by rupture of the inferior septum, resulting in isolated left posterior fascicular block. The development of isolated left posterior fascicular block complicating myocardial infarction may, therefore, serve to alert to the possible underlying septal rupture.
Angina pectoris with angiographically normal coronary arteries: A clinical, hemodynamic, and metabolic study
Authors: Berland J. , Cribier A. , Cazor J. L. , Hecketsweiler B. , Letac B. 
Published: February 2009

AbstractSeventy‐six patients with anginalike chest pain (ALCP) and angiographically normal coronary arteries (NCA) had a study of the myocardial metabolism at rest and during maximal atrial pacing. The results were compared with pain characteristics, electrocardiogram, left ventricular, and coronary hemodynamic data. Coronary blood flow (CBF) was measured by continuous ther‐modilution. At maximal paced heart rate, the study of the myocardial metabolism distinguished two groups: (1) a first group of 50 patients whose lactate extraction coefficient was equal to or exceeded 9 % and was considered as normal (Gr. I, K ≥9%); (2) a second group of 26 patients whose lactate extraction coefficient was below 9% (Gr. II, K<9%), significant of myocardial ischemia. In group I (K≥9%), chest pain was usually atypical (typical in only 25 % of cases) and rapid atrial pacing most often caused neither pain nor ECG changes. The hemodynamic and angiographic study showed minor alterations of the left ventricular cavity in 50% of cases. In group II (K<9%), chest pain was typical in 50% of the patients and maximal atrial pacing most often caused chest pain (85%) and ST‐segment depression (80%). In almost every case, the left ventricular and the coronary angiograms were normal. Only in this group, which had clinical, electrical, and metabolic signs of myocardial ischemia, could the diagnosis of angina pectoris with angiographically normal coronary arteries be upheld. However, resting CBF, % increase in CBF for an identical myocardial oxygen demand, and coronary resistances remained comparable in the two groups and no different from a group of 10 control subjects. This study confirms that myocardial ischemia occurs during rapid atrial pacing in 30% of patients with ALCP and NCA, with no obvious explanation, since coronary hemodynamics remain normal. In the remaining 70% of patients where no myocardial ischemia can be demonstrated minor forms of cardiomyopathy or mitral valve prolapse can often be shown.
Campylobacter jejuni myocarditis
Authors: Florkowski C. M. , Ikram R. B. , Crozier I. M. , Ikram H. , Berry M. E. 
Published: February 2009

AbstractA case of Campylobacter jejuni (C. jejuni) myocarditis in a young man is described. C. jejuni was isolated from the patient's stools and he developed specific antibodies to this organism. Tests for other etiological agents (Salmonella, Shigella, Brucella abortus, β‐hemolytic streptococcus Group A, Treponema pallidum and coxsackievirus B) proved negative.
Pseudocoarctation of the aortic arch in a patient with turner's syndrome
Authors: Klein L. W. , Levin J. L. , Weintraub W. S. , Agarwal J. B. , Helfant R. H. 
Published: February 2009

AbstractPseudocoarctation of the aortic arch is a rare congenital anomaly which resembles true coarctation by the presence of a narrowing in the descending thoracic aorta immediately distal to the origin of the left subclavian artery. However, it is differentiated from that entity by the absence of a significant hemodynamic obstruction and by the presence of aneurysmal dilatation proximal and distal to the area of narrowing. As a result, the commonly observed clinical findings of coarctation such as a prominent collateral circulation and decreased blood pressure in the lower extremities are not observed. “Kinking” or “buckling” are common adjectives used to describe the roentgenographic appearance of the aortic arch in this condition. The association of various congenital cardiac abnormalities with pseudocoarctation has been reported, and are similar to those commonly seen with true coarctation. We now present the first reported case of pseudocoarctation associated with a probable bicuspid aortic valve in a patient with Turner's syndrome.
Noninvasive recording of his bundle electrograms using vectorial leads system
Authors: Nojima K. , Otsuka K. , Otsuka K. , Seto K. , Mori H. 
Published: February 2009

AbstractHis bundle electrograms were recorded in 8 rats by a signal averaging technique using the Takayasu vectorial lead system. Animals were anesthetized and placed in the prone position. The polarity of three orthogonal leads were: the X axis, from right to left; the Y axis, from top to bottom; the Z axis, from back to front. Potentials from the X, Y, and Z leads were amplified by 20,000 with high‐pass 12 dB/octave filtering at 80 Hz, and signal averaging of 2000 beats was performed at a sampling interval of 100 μs. The His bundle potential could be clearly defined in all 8 rats. The mean amplitude of the His potential was larger in the X‐axis (23.6±9.2μV) or the Y‐axis (28.4±14.5μV) than the Z‐axis lead (11.5±8.6μV). Directions of the His potential vectors were to the left in 5 of 8 rats (62.5%), to the caudal in 4 of 6 rats (66.7%), and to the dorsal site in 6 of 8 rats (75.0%). This vectorial lead system, devised in accordance with McFee and Johnston's theory on lead field, was useful for recording His bundle electrograms.
Angioscopic visualization of blood vessel interior in animals and humans
Authors: Litvack F. , Grundfest W. S. , Lee M. E. , Carroll R. M. , Foran R. , Chaux A. , Berci G. , Rose H. B. , Matloff J. M. , Forrester J. S. 
Published: February 2009

AbstractThe purpose of this study is to describe the use of angioscopes in flowing bloodstreams of animals and humans, to demonstrate the ability to precisely deliver laser energy to an intravascular target using visual guidance and to determine the information content and spatial content of angioscopy. Angioscopy was performed in 5 living dogs, 16 cadaver vascular segments, and 14 patients at the time of peripheral or coronary bypass surgery. Five canine femoral artery segments received angioscopically directed intravascular Nd: YAG laser irradiation. We were able to precisely direct the laser irradiation to predetermined intimal targets. Gross tissue injury varied from none to carbonization and vascular perforation, depending on incident energy. Using a variety of flexible fiberoptic endoscopes ranging in diameter from 1.5 to 3.7 mm, we were able to visualize intravascular structures including plaque, suture lines, venous valves, and thrombi in living patients. No patient incurred complications of any sort. We conclude that angioscopy using flexible en doscopes can be performed safely, can provide clinically useful information, and may provide a means for delivering visually directed intravascular laser irradiation.
Changes in plasma catecholamine concentrations in patients with coronary heart disease during pacing and physical exercise
Authors: Dominiak P. , Grobecker H. , Delius W. 
Published: February 2009

AbstractTo study the difference in sympathetic activity during pacing the right atrium or during physical exercise in patients with coronary heart disease, we investigated circulating plasma catecholamine concentrations in the coronary sinus and brachial artery radioenzymatically in 11 male patients with well documented coronary artery disease. Heart rate was increased stepwise 20 beats/min from 90 beats/min up to 150 beats/min by pacing the right atrium and physical exercise was performed by increasing work load stepwise by 25 from 25 up to 100 W on an ergometric bicycle. Plasma noradrenaline and adrenaline concentrations were increased significantly only during physical exercise. In addition, there was an increase in arterial‐coronary sinus noradrenaline difference during graded physical exercise, whereas no further release of noradrenaline from the myocardium occurred during pacing. An enhanced cardiac sympathetic tone in patients with coronary heart disease is discussed. It is suggested that atrial pacing is not an adequate stimulus evoking an overall increase of cardiac and peripheral sympathetic tone.
Mitral valve prolapse syndrome with coronary artery spasm: A possible cause of recurrent ventricular tachyarrhythmia
Authors: Sakuma T. , Kakihana M. , Togo T. , Matsuda M. , Ogawa T. , Sugishita Y. , Ito I. , Kurusu T. 
Published: February 2009

AbstractA 54‐year‐old man with mitral valve prolapse syndrome diagnosed by echochardiography complained of anginal pain associated with ventricular tachyarrhythmia. One day he suddenly lost consciousness, and ECG at that time revealed ventricular fibrillation. Thereafter, he developed ST elevation, sporadic premature ventricular contractions, and R on T phenomenon leading to ventricular fibrillation during the attack of anginal pain. His coronary arteriogram was normal. This case implies that coronary artery spasm may be one of the causes of chest pain and ventricular tachyarrhythmias in patients with mitral valve prolapse syndrome.
A peculiar extra heart sound after artificial pneumothorax in congenital pericardial defect: A diagnostic clue
Authors: Hayashi Y. , Araki H. , Yamada A. , Tomoike H. , Nakamura M. 
Published: February 2009

AbstractA 37‐year‐old man was admitted to the hospital in order to evaluate the cause of systolic ejection heart murmur and to treat his easy fatigability. The chest roentgenogram showed a marked protrusion of the left second and third arches of the cardiac silhouette. At the diagnostic procedure, 200 ml of air was injected into the left thoracic space. The chest roentgenogram revealed no sign of pneumopericardium, but an abnormal extra heart sound was audible. Addition of another 200 ml of air was needed to reveal a pneumopericardium on the chest roentgenogram. A peculiar extra heart sound after artificial pneumothorax may be useful for the early recognition of congenital pericardial defect.
Cardiovascular response to static contraction in borderline hypertension
Authors: Seals D. R. , Hanson P. G. , Washburn R. A. , Painter P. L. , Ward A. , Nagle J. 
Published: February 2009

AbstractNine young males with borderline hypertension (BH) (mean age ± SD, 25 ± 5 yr) and 13 young male normotensive controls (NT) (24 ± 3 yr) were studied to determine their cardiovascular responses to small and large muscle static contractions. The subjects performed one‐arm handgrip and two‐leg extension in a randomly assigned order for 3 min at 30 % of maximal voluntary contraction. Mean intra‐arterial blood pressure (MABP), heart rate (HR), and tension were measured throughout the contractions. Borderline hypertensive patients had a higher MABP at rest (p< 0.005) and at the end of both types of static contractions (p<0.05). The average increases in MABP from rest to the end of exercise (ΔMABP) were slightly greater for the BH patients (6 mmHg), but these differences were not significant (p>0.1). However, a greater percentage of BH patients were hyperreactive to handgrip (ΔBP < 35 mmHg) and leg extension (ΔBP <40 mmHg) when compared to controls. These data indicate that, in general, young men with borderline hypertension demonstrate normal cardiovascular regulation in response to static contraction, but that a portion of this population may be hyperreactive to this type of circulatory stress.
Delayed shotgun pellet migration to the right ventricle
Authors: Levi B. , Sainsbury C. R. , Scharf D. L. 
Published: February 2009

AbstractMultiple case reports of bullet emboli to the heart have been documented. A unique clinical situation is presented of a patient who sustained a shotgun injury to the buttock, with retained pellets, who 7 to 10 years later demonstrated intravascular migration of one of the pellets to the intracardiac position.
A case of wolff‐parkinson‐white syndrome: Conduction through the kent bundle seems to depend on the serum potassium level
Authors: Nakahara Y. , Nakahara Y. , Matsuyama E. 
Published: February 2009

AbstractA 72‐year‐old man with Wolff‐Parkinson‐White syndrome and sick sinus syndrome had colon cancer, suggesting that the conduction of the Kent bundle depends on the serum potassium level. Because of severe diarrhea or furosemide administration, the serum potassium level in this patient was sometimes low. When it was less than 3.0 mEq/1 delta wave or re‐entrant tachycardia via the Kent bundle occurred. These were suppressed by the administration of potassium. On the other hand, when the serum potassium level was normal or high, neither effect was noted, and electrophysiological studies, done when the level was 3.2 mEq/1, showed no evidence of conduction by the accessory pathway. This suggests that conduction through the Kent bundle depends on the serum potassium level.
Paradoxical ventricular septal motion with right ventricular dilatation as a manifestation of pure pressure overload due to pulmonary veno‐occlusive disease
Authors: Zee‐Cheng C. S. , Gibbs H. R. 
Published: February 2009

AbstractParadoxical interventricular septal motion with right ventricular dilatation has been considered the hallmark of right ventricular volume overload. We report a 43‐year‐old woman with severe pulmonary hypertension due to pulmonary veno‐occlusive disease who exhibited these echocardiographic abnormalities. Right ventricular volume overload was excluded by physical examination, echocardiography with saline contrast study and by cardiac catheterization, angiography, and shunt study. These echocardiographic findings are thus not pathognomonic of right ventricular volume overload and can be seen with pressure overload as well.
The significance of repeated exercise testing with thallium‐201 scanning in asymptomatic diabetic males
Authors: Rubler S. , Fisher V.J. 
Published: February 2009

AbstractThis study was conducted with asymptomatic middle‐aged male subjects with diabetes mellitus to detect latent cardiac disease using noninvasive techniques. One group of 38 diabetic males (mean age 50.5±10.2 years) and a group of 15 normal males (mean age 46.9±10.0 years) participated in the initial trial; 13 diabetic patients and 7 control subjects were restudied 1‐2 years later. Maximal treadmill exercise with a Bruce protocol and myocardial scintigraphy with thallium‐201(201Tl) were used. Diabetic subjects on initial examination and retesting achieved a lower maximal heart rate and duration of exercise than control subjects. Abnormal electrocardiographic changes, thallium defects, or both were observed in 23/38 diabetic males (60.5%) on the first study and only one 65‐year‐old control subject had such findings. On retesting, the control subjects had no abnormalities while 76.9% of diabetic subjects had either 201Tl defects or ECG changes. We conclude that despite the fact that none of diabetic males had any clinical evidence or̀ symptoms of heart disease, this high‐risk group demonstrated abnormalities on exercise testing that merit careful subsequent evaluation and followup and could be an effective method of detecting early cardiac disease.