bluuebunny/crossref_metadata_2025_split huggingface dataset:
On the Genesis of the Absolute Ventricular Arrhythmia Associated with Atrial Fibrillation
Authors: YAMADO KAZUO , OKAJIMA MITSUHARU , HORI KAZUHIKO , FUJINO TETSURO , MURAKI HIROSHIGE , HISHIDA HITOSHI , KOBAYASHI TOSIJI 
Published: June 2012

Genetic factors in the formation of the long R-R interval in ventricular arrhythmia associated with atrial fibrillation were investigated in the isolated rabbit heart which was perfused using Langendorff's technique. The trans-membrane action potentials recorded from a single cell within the A-V node or within its vicinity were analyzed, and contiguous bipolar-lead electrograms simultaneously recorded from the right atrium and ventricle. Atrial fibrillation was induced by the combined application of acetylcholine solution and electrical stimulation. Atrial excitation was mainly blocked in the right atrium and in the anterior half of the A-V node.
To clarify further the time-correlation between the right atrial electrogram and the A-V nodal responses, the pattern of atrio-ventricular conduction was studied by applying only the electrical stimulation at high frequency without acetylcholine. The conduction was mainly blocked in the same sites as in the above experiment and the pattern of the conduction block in Wenckebach rhythm was observed. The conduction block within the anterior half of the A-V node may be the most important factor in producing the long R-R interval in atrial fibrillation. It was shown that the pattern of the conduction block can be explained by the Wenckebach rhythm.
Endotoxin-Induced Regional Circulatory Changes in the Unanesthetized Monkey
Authors: WYLER FELIX , FORSYTH RALPH P. , NIES ALAN S. , NEUTZE JOHN M. , MELMON KENNETH L. 
Published: June 2012

Endotoxin in eight unanesthetized monkeys produced a small decrease in cardiac output, a marked fall in blood pressure, and a decrease in total peripheral vascular resistance. The distribution of cardiac output was measured by injecting nuclide-labeled radioactive microspheres (50µ in diameter) into the left ventricle, and blood flow and vascular resistance were calculated for each organ. All vascular beds except that of the spleen reacted with variable degrees of vasodilation, and the most pronounced decreases in resistance were observed in the coronary, gastrointestinal, and adrenal vasculature. Cerebral flow was reduced, but flow was maintained in the brain stem and cerebellum. In contrast to studies in other species, both the gastrointestinal tract and the kidneys showed vasodilation and no significant decrease in flow during the early phase of endotoxemia.
There is some similar evidence in humans of decreased total systemic peripheral resistance without abnormal myocardial function or pooling of blood during the early phase of endotoxemia. The acute regional circulatory changes we have found appear to indicate that endotoxin either directly or through secondary biochemical reactions initiates and maintains a generalized (except for the spleen) vasodilation that reflex compensatory mechanisms cannot overcome. This vasodilation is particularly critical in preventing maintenance of adequate blood flow to the cerebral hemispheres.
Propagation of Blood Flow Pulse in the Normal Human Pulmonary Arterial System: ANALYSIS OF THE PULSATILE CAPILLARY FLOW
Authors: KARATZAS NICHOLAS B. , DE J. LEE GRANT 
Published: June 2012

We studied a number of dynamic events associated with the pulsatile flow of blood in the pulmonary arterial system of six healthy men in the supine position. We used the nitrous oxide-body plethysmograph method to record the pulmonary capillary blood flow pulse and the phonocardiogram to determine the time of opening and closing of the pulmonary valve. The pattern of right ventricular ejection was modified by administration of atropine and isoproterenol and by exercise.
The time of conduction of the flow pulse from the pulmonary valve to the lung capillaries averaged 120 msec. Acceleration of capillary blood during systole averaged 8.2 ml/sec/msec. The fraction of stroke volume which distended the pulmonary arterial system during systole averaged 67.2%. The peak flow rate averaged 186 ml/sec. Tachycardia resulted in a decrease in the fraction of the stroke volume stored in the arterial tree during systole. Isoproterenol and exercise resulted in an increase in average capillary blood acceleration. Conduction time is accounted for by pulmonary arterial distensibility, which also allows storage of the ejected blood during systole, which in turn helps to maintain continuity of blood flow in the capillaries. Despite these modifying effects of the pulmonary arterial system upon the flow wave, changes in the pattern of inflow pulse were detectable in the capillary flow pulse.
Hypertrophied Non-Failing Rat Heart: PARTIAL BIOCHEMICAL CHARACTERIZATION
Authors: Dart Charles H. , Holloszy John O. 
Published: June 2012

Cardiac hypertrophy was induced in rats by constructing an arteriovenous fistula. Heart weights approximately doubled in 7.5 weeks. The levels of activity, expressed per gram of heart, of a variety of enzymes of the mitochondrial respiratory chain and of the citric acid cycle, as well as the concentrations of cytochrome c and of mitochondrial protein, were the same in the hypertrophied and control hearts. Similarly, the capacity of whole heart homogenate to oxidize pyruvate was unaltered in hypertrophy.
There was also no change in the levels of activity of cytochrome oxidase and malate dehydrogenase, or in the concentration of cytochrome c in early hypertrophy (3 to 10 days after construction of an A-V fistula). These results suggest that cardiac mitochondria increase in parallel with the other components of the myocardial cell.
The levels of activity, per gram of heart, of creatine phosphokinase and adenylate kinase, and of the rate-limiting enzymes of glycolysis and glycogenolysis, were the same in the hypertrophied and the control hearts.
The above findings suggest that the capacity, per gram of heart, for regenerating ATP, both aerobically and anaerobically, is unchanged in the non-failing, hypertrophied heart.
Velocity Profiles in the Main Pulmonary Artery of Dogs and Man, Measured with a Thin-Film Resistance Anemometer
Authors: REUBEN S. R. , SWADLING J. P. , LEE G. DE J. 
Published: June 2012

Instantaneous velocity of pulmonary artery blood was measured using a thin-film resistance anemometer mounted on a hypodermic needle. Studies were performed, at thoracotomy, in five dogs and five patients. Instantaneous blood velocity was recorded at several sites across the transverse axis of the main pulmonary artery to determine the shape of the velocity profile.
We found the velocity profile, in both man and dog, to be approximately flat. In dog, the mean velocity, normalized to that at the center line, ranged from 1.18 (SD ± 0.03) to 0.81 (SD ± 0.27). In man, mean velocity of pulmonary artery blood, normalized in a similar fashion, ranged from 1.08 (SD ± 0.03) to 0.84 (SD ±0.07), while the normalized peak systolic velocity ranged from 1.04 (SD ± 0.07) to 0.95 (SD ± 0.16). The results, in dogs, suggest that there is little asymmetry of the velocity profile and therefore these have been taken as evidence that the use of cuff electromagnetic flowmeters on the pulmonary artery of dogs is not subject to significant inaccuracies associated with a nonsymmetrical flow profile. The finding of a relatively flat velocity profile in patients, moreover, will make it easier for catheter-tip flowmeters to measure bulk velocity in the pulmonary artery.
Autonomic Control of Cardiac C-AMP
Authors: LARAIA PAUL J. , SONNENBLICK EDMUND H. 
Published: June 2012

Although catecholamines are known to increase cyclic adenosine 3'5'-monophosphate (C-AMP) in heart muscle, the relations of adrenergic and cholinergic mechanisms to inotropy and myocardial C-AMP levels and adenyl cyclase have not been defined. Accordingly, atrial and	ventricular muscle preparations were studied in a myograph with a tension recorder. Adenyl cyclase, phosphodiesterase, and C-AMP were measured by chromatographic and isotopic methods. In atrial preparations, norepinephrine (10
-5
M
) increased tension by 80±10% (mean±
SE
), adenyl cyclase by 40±10% and C-AMP by 75±12%, while carbamylcholine chloride (10
-4
M
) reduced tension by 65±10%, adenyl cyclase by 30±12% and C-AMP by 50±14%. The effects of carbamylcholine chloride on tension, adenyl cyclase, and C-AMP were blocked by atropine 10
-5
M
. In paced ventricular (papillary) muscles, norepinephrine (10
-5
M
) increased tension by 70±10%, adenyl cyclase by 50±11% and CAMP by 90±17%. In contrast, carbamylcholine chloride (10
-5
M
) reduced tension by only 7±5%, adenyl cyclase by 12±8%, and C-AMP by 10±7%. These results demonstrate parallel changes in tension, adenyl cyclase, and C-AMP in atrium and ventricle. The failure of ventricular muscle to respond to carbamylcholine is mirrored by the adenyl cyclase system and C-AMP. Furthermore, the cholinergically mediated tension and adenyl cyclase changes in atria were specifically blocked by atropine. Thus these results relate the different effects of cholinergic agents on atrium and ventricle to adenyl cyclase and C-AMP, and suggest specific receptor localization in these two types of myocardia.
Influence of Coronary Artery Pressure Upon Myocardial Elasticity
Authors: SALISBURY PETER F. , CROSS CECIL E. , RIEBEN P. ANDRE 
Published: June 2012

The marked intensification of experimental left ventricular failure by veno-arterial pumping which was seen in earlier experiments suggested changes of myocardial elasticity as a mechanism. Two experimental procedures were therefore applied here, in which the pressure in the coronary arteries and veins could be varied at will, where the left ventricle was distended by an air-filled balloon, and where the coronary tree did not communicate with the left ventricle. Changes of the coronary arterial or venous pressures were accompanied by homodirectional changes of the left ventricular diastolic pressure which were of large magnitude and which could not be explained by unobserved blood flow into the left ventricle or by other factors.
The inverse relationship between coronary vascular pressures and myocardial distensibility was probably caused by the increasing volume of blood which was retained in the coronary arteries and veins when the coronary arterial or venous pressures were increased. This passive increase in coronary blood volume (turgor) must have changed the resiliency of the coronary tree. The changed elastic properties of the coronary tree then resulted in a change of the elastic properties of the heart.
Hemodynamic Effects of a Pressor Amine (Methoxamine) with Predominant Vasoconstrictor Activity
Authors: BREWSTER WILLIAM R. , OSGOOD PATRICIA F. , ISAACS JAMES P. , GOLDBERG LEON I. , W Chock Raymond T. 
Published: June 2012

A pressor amine (methoxamine) which produces peripheral vasoconstriction, while lacking a significant, direct, positive inotropic effect upon ventricular heart muscle, has been shown to produce hemodynamic effects that are in distinct contrast to those resulting from the injection or infusion of
l
-epinephrine and
l
-norepinephrine in "physiologic" concentrations or of mephentermine sulfate. The latter 3 amines, possessing a positive inotropic action in addition to varying vasoconstrictor effects, decrease right and left atrial mean pressures while increasing femoral and pulmonary arterial pulse and mean pressures, right and left ventricular stroke works and the cardiac index.

Methoxamine injection or infusion, in contrast, resulted in linear increases in the calculated total peripheral resistance and left and right atrial mean pressures. There was a simultaneous rise in right and left ventricular stroke works which were maintained until a maximum rise in the mean arterial pressure was reached. The average stroke volume indices were maintained at near control values in both blocked and unblocked animals. The cardiac index of the normal unblocked dogs decreased in proportion to the decrease in heart rate.
Following the peak pressor response to methoxamine, a progressive fall in mean femoral arterial pressure occurred resulting from ventricular failure rather than "tachyphylaxis" to the vasoconstrictor activity of methoxamine. This decrease in systemic arterial pressure was accompanied by: (1) a further rise in calculated total peripheral resistance and in right and left atrial mean pressures, and (2) a fall in right and left ventricular stroke work and stroke volume indices and in the cardiac indices.
Oxygen Consumption of Normal and Atherosclerotic Intima
Authors: WHEREAT ARTHUR F. 
Published: June 2012

This investigation has been a comparison of the intimal metabolism of the aorta in normal and atherosclerotic rabbits, and at various aortic locations. The thinnest possible layer of tissue was separated from the inner surface of the aorta. This layer proved to be intima with a small and fairly constant amount of media (smooth muscle).
The intima from the animals rendered atherosclerotic by cholesterol-feeding showed a much higher rate of oxygen consumption than the controls when succinate was used as a substrate. Moreover, the most atherosclerotic area (the aortic arch) showed a higher oxygen consumption than the less atherosclerotic areas (the thoracic and abdominal areas). This acceleration of oxygen consumption is presumably due to either an increased energy requirement (for either accelerated synthesis or catabolism) or an uncoupling of oxidative phosphorylation.
Inflammation and Not Cardiovascular Risk Factors Is Associated With Short Leukocyte Telomere Length in 13- to 16-Year-Old Adolescents
Authors: Masi Stefano , Nightingale Claire M. , Day Ian N. M. , Guthrie Philip , Rumley Ann , Lowe Gordon D. O. , von Zglinicki Thomas , D’Aiuto Francesco , Taddei Stefano , Klein Nigel , Salpea Klelia , Cook Derek G. , Humphries Steve E. , Whincup Peter H. , Deanfield John E. 
Published: June 2012

Objective—
Short leukocyte telomere length (LTL) is associated with cardiovascular (CV) disease in adulthood. However, the biological basis of this association remains unclear. We sought to define early determinants of the association between CV disease and LTL in an adolescent population.

Methods and Results—

One thousand eighty adolescents, aged 13 to 16 years and participating in the Ten Towns Heart Health Study, provided blood samples for DNA extraction and measurement of a range of CV risk factors. LTL was measured by real-time polymerase chain reaction. LTL was inversely associated with age (
P
=0.04), longer in females than in males (
P
=0.03), and longer in South Asians than in white Europeans (
P
=0.01). No associations were found between LTL and traditional CV risk factors. There was a significant and inverse association between LTL and inflammatory markers, including C-reactive protein (
P
<0.001) and fibrinogen (
P
=0.001). The associations between LTL and inflammatory markers were not affected by multiple adjustments for behavioral and metabolic factors.

Conclusion—
High levels of inflammation are associated with shorter LTL from early adolescence; traditional CV risk factors have little association with LTL in adolescence. Inflammation in early life may play a causal role in the adult association between short LTL and CV disease.
Size and Ionic Currents of Unexcitable Cells Coupled to Cardiomyocytes Distinctly Modulate Cardiac Action Potential Shape and Pacemaking Activity in Micropatterned Cell Pairs
Authors: McSpadden Luke C. , Nguyen Hung , Bursac Nenad 
Published: June 2012

Background—
Cardiac cell therapies can yield electric coupling of unexcitable donor cells to host cardiomyocytes with functional consequences that remain unexplored.

Methods and Results—

We micropatterned cell pairs consisting of a neonatal rat ventricular myocyte (NRVM) coupled to an engineered human embryonic kidney 293 (HEK293) cell expressing either connexin-43 (Cx43 HEK) or inward rectifier potassium channel 2.1 (Kir2.1) and Cx43 (Kir2.1+Cx43 HEK). The NRVM–HEK contact length was fixed yielding a coupling strength of 68.9±9.7 nS, whereas HEK size was systematically varied. With increase in Cx43 HEK size, NRVM maximal diastolic potential was reduced from −71.7±0.6 mV in single NRVMs to −35.1±1.3 mV in pairs with an HEK:NRVM cell surface area ratio of 1.7±0.1, whereas the action potential upstroke ([d
V
m
/d
t
]
max
) and duration decreased to 1.6±0.7% and increased to 177±32% in single NRVM values, respectively (n=21 cell pairs). Pacemaking occurred in all NRVM–Cx43 HEK pairs with cell surface area ratios of 1.1 to 1.9. In contrast, NRVMs, coupled with Kir2.1+Cx43 HEKs of increasing size, had similar maximal diastolic potentials, exhibited no spontaneous activity, and showed a gradual decrease in action potential duration (n=23). Furthermore, coupling single NRVMs to a dynamic clamp model of HEK cell ionic current reproduced the cardiac maximal diastolic potentials and pacemaking rates recorded in cell pairs, whereas reproducing changes in (d
V
m
/d
t
)
max
and action potential duration required coupling to an HEK model that also included cell membrane capacitance.

Conclusions—
Size and ionic currents of unexcitable cells electrically coupled to cardiomyocytes distinctly affect cardiac action potential shape and initiation with important implications for the safety of cardiac cell and gene therapies.
Biocompatibility Comparison of Novel Soft Tissue Implants vs Commonly Used Biomaterials in a Pig Model
Authors: Kolb Caroline M. , Pierce Lisa M. , Roofe Scott B. 
Published: June 2012

ObjectiveTo develop a model to evaluate biocompatibility, integration, and substrate independence of novel porous bioscaffolds for maxillofacial and plastic reconstruction using sphere‐templated angiogenic regeneration technology compared with currently available synthetic and biologic soft tissue implants.Study DesignA prospective pilot study using animals.SettingMilitary medical center.Subjects and MethodsFive pigs underwent dorsal subcutaneous implantation of a polypropylene‐based material coated with precision pore silicone granules (sphere‐templated scaffold), expanded polytetrafluoroethylene, human dermis, and porcine dermis. Sham and undissected sites were also used as controls. Specimens were harvested 7, 21, 90, and 180 days after surgery and evaluated histologically for inflammation, neovascularization, and collagen deposition.ResultsAll materials and sham sites induced a mild to moderate inflammation that decreased over time, except for human dermis, which elicited a moderate to severe inflammatory response. The responses were varied and measurable using subjective scoring methods. The sphere‐templated scaffold demonstrated numerous foreign body giant cells adjacent to the silicone granules, which were not seen in any of the other specimens.ConclusionSubjective scoring of pathology slides and measurement of capsule thickness appeared to show differences between the materials, but these differences require a larger number of subjects and proper statistical analysis to assess. The robust foreign body reaction elicited by the polypropylene/silicone‐based scaffold argues against the use of this material in future studies. The authors advocate using inert biodegradable substances for future bioscaffold constructs.
The effects of zero-balance ultrafiltration on postoperative recovery after cardiopulmonary bypass: a meta-analysis of randomized controlled trials
Authors: Zhu X , Ji B , Wang G , Liu J , Long C 
Published: June 2012

Objective: Considered as a significant ultrafiltration technology during cardiopulmonary bypass (CPB), zero-balance ultrafiltration (Z-BUF) has always received controversial support regarding its effectiveness in reducing inflammatory mediators in plasma. Therefore, we conducted a meta-analysis to evaluate the clinical effect of Z-BUF through screening all relevant published randomized controlled trials (RCTs). Methods: A comprehensive search was conducted to screen all RCTs of Z-BUF. Three trained investigators searched databases, including PubMed, Embase, the Cochrane Library, Google scholar, and Chinese literature databases (CNKI, WanFang, WeiPu). RCTs that compared Z-BUF with non-ultrafiltration were included. We focused on clinical outcomes such as length of stay in ICU, duration of ventilation, hospital stay, total amount of chest tube drainage and mortality. Finally, a total of 7 studies containing appropriate criteria were divided into an adult group and a pediatric group. A random effects model was used to calculate weighted mean difference with 95% confidence intervals. Results: In the adult group, the benefits of Z-BUF in duration of ventilation (WMD=-2.77, 95% CI = [-6.26, 0.72], I2=71%, p=0.12) and the length of ICU stay (WMD=-4.13, 95% CI = [-10.09, 1.84], I2=77%, Z=1.36, p=0.17) were not apparent, with significant heterogeneity existing in the statistical results. The rest of the clinical parameters could not be evaluated due to insufficient data. In the pediatric group, combined analysis showed Z-BUF could reduce the duration of mechanical ventilation (WMD=3.07; 95%CI= [-7.56, -3.46], I2=17%, p=0.27). The advantage of Z-BUF was not observed in other clinical outcomes. Conclusion: The benefits of Z-BUF were not apparent, according to the report. Further studies involving combined ultrafiltration are expected to provide improved ultrafiltration during CPB.
A Systematic Review of Complications and Failures Associated With Medial Patellofemoral Ligament Reconstruction for Recurrent Patellar Dislocation
Authors: Shah Jay N. , Howard Jennifer S. , Flanigan David C. , Brophy Robert H. , Carey James L. , Lattermann Christian 
Published: June 2012

Background: Patellofemoral instability affects activities of daily living and hinders athletic participation. Over the past 2 decades, more attention has been paid to medial patellofemoral ligament (MPFL) reconstruction for the treatment of recurrent patellar dislocations/subluxations. Numerous techniques have been reported; however, there is no consensus regarding optimal reconstruction. Purpose: This study sought to report on the various techniques for MPFL reconstruction described in the literature and to assess the rate of complications associated with the procedure. Study Design: Meta-analysis. Methods: A systematic review of the literature was performed in early October 2010 using keywords “medial patellofemoral ligament,” “MPFL,” “reconstruction,” “complication(s),” and “failure(s).” Articles meeting the inclusion criteria were reviewed. Graft choice, surgical technique, outcome measures, and complications were recorded and organized in a database. Descriptive statistical analysis was performed on the data collected. Results: Twenty-five articles were identified and reviewed. A total of 164 complications occurred in 629 knees (26.1%). These adverse events ranged from minor to major including patellar fracture, failures, clinical instability on postoperative examination, loss of knee flexion, wound complications, and pain. Twenty-six patients returned to the operating room for additional procedures. Conclusion: Medial patellofemoral ligament reconstruction has a high rate of success for patients with patellofemoral instability; however, the complication rate of 26.1% associated with this procedure is not trivial. This study quantified complications and documented the variety of complications reported in outcomes-based literature.