bluuebunny/crossref_metadata_2025 huggingface dataset:
Left Ventricular Pressure -Volume Relationships and Myocardial Oxygen Consumption in the Isolated Heart
Authors: MONROE R. GRIER , FRENCH GORDON N.
Published: June 2012

An isolated dog-heart preparation, in which absolute volumes were known, was employed to determine left ventricular pressure-volume relationships and myocardial oxygen consumption. Loading was varied from the extreme of zero pressure change to zero volume change during systole. Maximum peak systolic pressures were developed by isovolumetric, and maximum stroke volumes by isobaric contractions. When the load was varied to allow both pressure and volume to change in systole, the peak systolic pressures and the simultaneously determined ventricular volumes could be plotted as a "peak systolic pressure-volume line." Moderate changes in diastolic volume had little effect on the position of the line, and the mechanical work of the heart appeared to depend on the nature of the load rather than the diastolic volume. Epinephrine and digitalis glycosides did not affect diastolic pressure-volume relationships. Heart rate affected the diastolic pressure-volume curve only at rapid rates, where changes in the rate of relaxation produced apparent differences in compliance. Myocardial oxygen consumption is shown to be correlated with peak systolic pressure or volume, and is not mainly determined by either diastolic volume or stroke work.
Influence of Airway Pressures on Edema in the Isolated Dog's Lung
Authors: WAGNER ERICH , RIEBEN P. ANDRE , KATSUHARA KIMIKO , SALISBURY PETER F.
Published: June 2012

The left lower lobe of anesthetized, heparinized dogs was excised, weighed, and cannulated. Another lobe of the same dog was excised for control purposes. The cannulated lobe was perfused by a system of adjustable reservoirs which was fed with fresh blood from a donor dog. The perfused lobe was mounted on an electronic balance so that weight changes could be recorded together with the pressures in the inflow and outflow conduits and in the bronchus. When the per fusion pressures were varied within normal limits, the weight of the lobes reached stable plateaus. Abnormally high perfusion pressures caused a continuous, steady increase in lobe weight, which was evident from the slope of the weight registration. Blood holdup in the lobe was measured by comparing the hemoglobin content of the control lobe with that of the experimental specimen taken at the end of an experiment. Blood holdup accounted for only about 10 per cent of the weight increase of edematous lobes. Initial observations were made in collapsed lobes; in the course of some experiments these lobes were inflated and the static airway pressures were then kept at varying levels.

Irrespective of the perfusion pressures, transudate did not issue from the airway as long as the lobe was collapsed. Abnormal perfusion pressures caused the accumulation of fluid, which continued as long as the perfusion pressures were constant. The rate of transudation was determined by the perfusion pressures and was not influenced by inflation of the collapsed lobe nor by variations of the static airway pressure. When a collapsed lobe had become edematous anti was then inflated, transudate issued from the airway. Increases of the static airway pressure did not decrease the rate of fluid accumulation, but only confined the transudate to the lung and prevented its discharge from the airway.
Release of Pressor Substances from Renal Grafts Originating from Rats with Renal Hypertension
Authors: OMAE TERUO , MASSON GEORGE M. C. , PAGE IRVINE H.
Published: June 2012

A method is described for grafting kidneys on bilaterally nephrectomized rats without interrupting renal blood flow. Under these conditions, normal kidneys caused a pressor response characterized by a gradual rise in pressure suggesting a continuous endocrine secretion. Kidneys from rats made hypertensive by unilateral clipping of the renal artery, renal encapsulation, or partial infarction were tested during the acute and chronic stages of the experimental disease. Wrapped and infarcted kidneys, as well as the untouched contralateral organs, released little or no pressor substances. On the other hand, clipped kidneys released normal or slightly greater amounts of pressor substances; the eontralateral untouched kidney did not elicit any pressor effect. Morphological examination showed a relationship between presence of nephroselerotic lesions and absence of, or decrease of, reninlike pressor substance released. Both changes are believed to be due to high renal vascular pressure against which the partly clipped kidney is protected.

These observations suggest that, if renin is a primary factor in the pathogenesis of renal hypertension, hypertension due to renal artery constriction has a mechanism different from that caused by renal manipulation or infarction.
Electrocardiographic Effects of Changing the Nature of the Contact Between the Exposed Heart and the Body
Authors: SAYEN JOHN J. , KATCHER AARON H. , PEIRCE GEORGE
Published: June 2012

In dog studies designed to improve the accuracy of direct extracellular heart-body leads, the electrocardiographic representation of the heart when maximally insulated (connected to the body only by its vascular pedicdc) was compared with common open-chest experimental situations in which portions of the normally behaving ventricular surface are allowed to remain in contact with the body. The addition of any ventricular surface to the heart-body contact area (by removal of insulation) lowered the R-wave amplitude in all. direct heart-body leads from the ventricular surface or wall.

The effects of locally altering the physiological behavior of portions of the left ventricle were also studied. Any portion of the ventricular surfaces of maximally insulated hearts could be altered by locally applied agents to show heart-body lead changes entirely confined to the area of demonstrably local physiological disturbance. Small- or medium-sized areas of transmural regional is chemia likewise produced electrocardiographic changes only in the vicinity of the ischeniic muscle. In the case of less completely in Sn lated hearts, direct heart-body lead changes consequent to localized physiological change
Effects of Digitalis Upon Body Electrolytes
Authors: LOWN BERNARD , WHIPPLE GERALD H. , MCLEMORE GEORGE , LEVINE SAMUEL A.
Published: June 2012

Studies of the electrolyte alterations in 54 dogs during 165 discrete digitalizations with acetyl strophantbidin to an endpoint of ventricular tachycardia are reported. In 94 per cent of digitalizatious, increase in arterial potassium concentration occurred. This was noted as early as five niinutes after drug administration. At the time of ventricular tachycardia, the increase was 0.67 mEq./L. When digitalization was carried to ventricular fibrillation, the increase was 3.1 mEq./L. In 75.5 per cent of the digitalizations, arterial sodium concentration decreased; average de crease was 2.6 mEq./L. At ventricular fibril lation, the decrease amounted to 11.0 mEq./L. Arterial calcium concentration and oxygen saturation were not altered. There was a modest decrease in CO
2
content and an increase in arterial pH and hcmatoerit. Peaking of the late portion of the T wave was common during acute digitalization and correlated with the increase in extracellular potassium concentration. The relationship of the electrolyte changes to the process of digitalization is discussed.
Effects of Work Loads Applied at Various Times in the Cardiac Cycle of the Isolated Dog Heart
Authors: ZEIG NORMAN J. , BUCKLEY NANCY M. , PORTER EREST P.
Published: June 2012

Effects of work loads imposed at various times in the cardiac cycle were studied in isolated left ventricle preparations of dog hearts. In six preparations, resistance loads were applied briefly at times in ventricular systole; in six, volume loads were applied briefly at times in ventricular diastole; in six, experimental aortic regurgitation was produced. Simultaneous recorc1s of left ventricular and aortic pressures and electrocardiograms were used to cletermilie the subdivisions of the cardiac cycle and to measure the rates of isometric contraction and relaxation for evaluation of changes in ventricular contractility. The results of many observations indicated that the rates of isometric ventricular contraction and relaxation were not fixed by prior events, that contraction and relaxation could be altered independently, and that aortic regurgitation loaded the left ventricle at a time critical for its relaxation. Accommodation to aortic regurgitation included maintenance of contractility without diastolic left ventricular pressure rise; failure of accommodation was characterized by loss of contractility at high diastolic ventricular pressure.
Effects of Catecholamines and Atropine on Cardiovascular Response to Exercise in the Dog
Authors: KECK ERNST W. O. , ALLWOOD MICHAEL J. , MARSHALL ROBERT J. , SHEPHERD JOHN T.
Published: June 2012

The manner in which the administration of epinephrine, norepinephrine, isoproterenol, and atrophic modifies the cardiovascular response to exercise has been studied in 12 dogs.

In control observations, exercise increased the cardiac output by 116 per cent, the heart rate by 102 per cent, and the stroke volume by 8 per cent. When epinephrine was infused during identical exercise, the cardiac output was similar; however, the stroke volume was increased by 50 per cent. During infusion of norepinephrine, the cardiac output was reduced by 11 per cent compared with that during control exercise, and the stroke volume was increased by 25 per cent. With isoproterenol, the cardiac output exceeded that during control exercise, but the stroke volume was unchanged.

Prior to administration of atropine, the cardiac output at rest averaged 4.2 L. per minute. After injection of atropine, the cardiac output averaged 3.7 L. per minute, the heart rate increased from 121 to 249 beats per minute, and the stroke volume decreased from 35 to 15 ml. Before atropinization, the cardiac output, heart rate, and stroke volume during exercise were increased by 95, .90, and 2 per cent over the resting values; after atropinization, the corresponding increases were 110, 7, and 100 per cent.

Thus, while cardiac output during exercise normally is regulated mainly by changes in the heart rate, the stroke volume may make a major contribution under other circumstances.
Cardiac Nucleotides and Derivatives in Acute and Chronic Ventricular Failure of the Dog Heart
Authors: BUCKLEY NANCY M. , TSUBOI KENNETH K.
Published: June 2012

The levels and proportionate distribution of nucleotides, nucleosides, and bases were determined in myocardial samples from two freshly excised hearts, three acutely failing left ventricle preparations in which the nonworking right ventricle served as control, and two hearts from dogs in which aortic regurgitation was produced surgically as a source of chronic overload of the left ventricle. Ventricular performance was evaluated from cardiac function studies, including measurements of cardiac output, stroke work, and contractility. The compounds identified by chromatographic resolutions were AMP, ADP, ATP, DPN, UPP, and GPP; inosine and hypoxanthine; and uridine and uracil. Qnantitative analyses revealed no consistent difference in specific composition of nonfailing and acutely or chronically failing ventricles.
Sensitivity of the Large Blood Vessels of the Rabbit to
l
-Epinephrine and
l
-Norepinephrine
Authors: BEVAN JOHN A.
Published: June 2012

Some of the pharmacological properties of the smooth muscle of 17 anatomically different vessels of the adult rabbit have been compared using helical strips under in vitro conditions. Using the median effective dose and the slope of the logarithm dose-probit response curve for
l
-epinephrine and
l
-norepinephrine as criteria, these vessels may be divided into two groups. The vascular muscle of the thoraeic and abdominal aorta, the femoral, main pulmonary and lobar pulmonary arteries, some preparations of the renal arteries and the inferior vena cava exhibit, within 95 per cent confidence limits, identical characteristics. They are more sensitive to
l
-norepinephrine than
l
-epinephrine, and the slopes of thc dose-response curves to these amines are the same. The muscle of the common carotid and saphena arteries and the external jugular vein is very similar to this group, but not identical. The vascular muscle of the common iliac, brachial, facial, anterior and posterior mesenteric, and celiac arteries, and the portal vein is less sensitive, and the slope of the dose-response curve more steep to these amines than the previous group. They are more sensitive to
l
-epinephrine than
l
-norepinephrnie and the slopes of the dose-response curves for these amines are not the same.
Low and High Magnesium Concentrations at Various Calcium Levels
Authors: SURAWICZ BORYS , LEPESCHKIN EUGENE , HERRLICH HERMAN C.
Published: June 2012

Electrocardiograms, ventricular monophasic action potentials registered with suction and intracellular microelectrodes, and pressure curves were recorded simultaneously in isolated rabbit hearts perfused with oxygenated Krebs-Henscleit solution containing varying calcium/magnesium ratios. The duration of the action potential and Q-T interval was not affected by low and high magnesium concentrations unless calcium was omitted or significantly reduced. When Mg was completely absent, solutions free of calcium or with one-sixteenth of the "normal" Ca concentration caused a progressive prolongation of the action potential and Q-T interval until they occupied the entire cardiac cycle. When Mg concentration was low (0.075 to 0.6 mM/L.), the prolongation occurred at a slower rate and was less pronounced. With higher Mg concentrations (1.2 to 19.2 mM/L.), the initial lengthening of the action potential and Q-T interval was followed by a gradual shortening. The higher the Mg concentration employed, the shorter was the period of the initial lengthening, and the more pronounced was the subsequent shortening. These observations can be best explained by assuming that calcium-like action of Mg on the plateau of the action potential becomes apparent only when Ca is absent or significantly decreased. The depression of contractility by calcium deficiency proceeded at the same rate at all studied Mg concentrations. The findings are discussed in relation to the electrocardiographic patterns encountered in clinical cal cium and magnesium deficiency.
Degenerative Changes in the Cardiovascular System of the Spawning Pacific Salmon (
Oncorhynchus tshawytscha
)
Authors: ROBERTSON O. H. , WEXLER BERNARD C. , MILLER BENJAMIN F.
Published: June 2012

In a stndy of the cardiovascular system of spawning Pacific salmon, degenerative changes were found in the heart muscle, coronary and visceral arteries, and capillaries of the kidney glomeruli. The heart muscle showed vacuolization of the muscle fibers with loss of fibrils, deposition of collagen, and cartilaginous meta plasia. Changes in the coronary and visceral arteries consisted of intimal hyperplasia with deposition of mucopolysaccharides, disruption of the internal elastic membrane, and destruction of adjacent muscle fibers in the media. The glomerular capillaries showed marked sclerosis. The resemblance of the arterial changes in the salmon to the beginning mani festations of arteriosclerosis in man, mammals, and birds is pointed out, and the relationship of the salmon's state of hyperadrenoeorticism to the occurrence of the vascular lesions is discussed.
Experimental Verification of Wilson's Derivation of the Principle of the Ventricular Gradient
Authors: GARDBERG MANUEL , ROSEN IRVING L.
Published: June 2012

The concept of the ventricular gradient is based upon the theoretical representation of the electrogram of a myocardial fiber as the sum of two monophasic action potential (M.A.P.) curves, each of which represents the electrical activity of one-half of the fiber. Wilson showed that from this premise certain mathematical deductions are possible: (1) that the area of the electrogram is equal to the sum of the areas of the two MAP. curves; (2) that this area is independent of the rela tion of the two M.A.P. curves with respect to time and, therefore, that it is independent of the path of excitation; and (3) that as a corol lary of the latter, the measurement of the area of the electrogram may be used as a measure of the net electrical effect of local differences in repolarization.

The present paper reports the results of experiments in which the electrical effects of a segment of a strip of turtle heart muscle were recorded as biphasic complexes and as two M.A.P. curves. Accurate measurement of the areas by means of an electronic integrator supports Wilson's premise. These observations furnish experimental confirmation of the theo retical basis of the concept of the ventricular gradient.
Myocardial Coefficient of Oxygen Utilization
Authors: SCOTT JOHN C.
Published: June 2012

An analysis of blood oxygen values, coronary blood flow, and left ventricular oxygen consumption has been made on data obtained from 120 experiments on normal anesthetized dogs by using the N
2
O method for estimating coronary flow. The arterial oxygen content was shown to have a positive linear relationship to the myocardial arteriovenous oxygen difference (A-V,O
2
), but a negative linear relationship to coronary flow. The coefficient of oxygen utilization showed a positive linear regression with arterial oxygen-content values above 20 volumes per cent, but an inverse relationship with arterial oxygen values below 20 volumes per cent. The significance of these relationships in the regulation of coronary flow is discussed.
Transport of K
42+
, Na
24+
, and I
131
+ by the Pulmonary Circulation
Authors: YUDILEVICH DAVID
Published: June 2012

The transport of K
42+
, Na
24+
, and I
131+
by blood through the heart and lungs in the canine heart-lung preparation was studied. Simultaneous injection of each tracer was performed together with nondiffusible Risa as a reference label. The data show that in a single passage through the lung, a fraction of the injected radioactive electrolyte moves out from the blood and partially returns. This alters the shapes of the dilution curves and the results of cardiac output and central volume calculations. The implications of these findings in the suggested use of radioactive electrolytes for the application of the Stew art-Hamilton method in human and animal investigations is discussed. The possibility is suggested that in the Starling preparation, the difference in flows calculated from the extrapolated and complete dilution curves of a non-diffusible tracer may he related to the coronary flow.
Dilution Curves of Simultaneously Administered 1
131
-Human Serum Albumin and Cr
51
-Labeled Erythrocytes in Patients with Various Types of Edema
Authors: TUCKMAN JOHN , FINNERTY FRANK A.
Published: June 2012

Detailed indicator-dilution curves of simul taneously administered 1
131
-HSA and Cr
51
-RBC in six of eight edematous patients with congestive heart failure demonstrate that, as in normal patients, a significant quantity of 1 does not escape the intravascular space during the first several minutes post injection. It would seem, therefore, that cap illary permeability to albumin was not an im portant manifestation in these patients. De tailed indicator-dilution curves in five of six patients with edema not associated with con gestive heart failure differ from those derived from normal patients and from the edematous patients with congestive heart failure. These data do not exclude the possibility that capillary permeability to albumin might be a sig nificant concomitant of edema associated with chronic glomerulonephritis, disseminated lupus erythematosis, toxemia of pregnancy. car cinomatosis, and Kimmelstiel-Wilson syndrome.
Comparative Effects of d-and L-3,5,3'-Triiodothyronine in Chronic Treatment of Hypercholesteremic Dogs
Authors: ELLISON THEODORE , GREENBERG SAMUEL M. , LIN TIEN-HUI
Published: June 2012

Twenty intact, naturally hypercholestere-mic dogs were divided into five groups and chronically administered D-3,5,3'-triiodothy-ronine (d-T3) and L-3,5,3'-triiodothyronine (l-T3) at two levels, respectively, for 31 weeks. The administration of the drugs was divided into two periods, the first for 21 weeks, after which the dosage level for each of the four test groups was doubled for an additional 10 weeks. Plasma total cholesterol, total lipids, and phospholipids were significantly lowered by the administration at both levels of d-T3 and the higher level of l-T3. At the end of 21 and 29 weeks of thyromimetic administration, no differences in percentage of free or esterified cholesterol were observed for any of the treated groups when compared with the control groups. A battery of physiological and functional tests was performed at suitable intervals throughout the experimental period with no evidence of abnormalities due to the administration of the thyromimetic agents. The only significant functional change measured was a reduction in protein-bound-iodine levels in the clogs receiving the higher level of l-T3.

Throughout the entire experiment, all dogs remained in good health as judged by gross appearances and actions. The dogs receiving d-T3 gained less weight than did either the controls or the L-T3-treated groups, even though all animals ate isocaloric balanced diets. At post mortem, after 31 weeks of chronic thyromimetic administration, gross pathology was negative; chemical analyses of cholesterol content of aortas, adrenals, and livers indicated no significant differences. Analyses of livers for total lipids showed no significant differences, and no evidence of aortic sudanophilia was apparent in any of the experimental dogs.
Collateral Blood Flow to the Myocardium as Determined by the Clearance of Rubidium
86
Chloride
Authors: LEVY MATTHEW N. , IMPERIAL ELTAS S. , ZIESKE HARRISON
Published: June 2012

The left circumflex coronary artery was li gated in anesthetized dogs, and the blood flow to the normal and ischemic regions was esti mated by means of the Rb
86
clearance tech nique. Time occlusion of this coronary artery resulted in an appreciable reduction in the Rb
86
clearance, principally in the posterior region of the left ventricle bounded by the circumflex artery, the posterior descending branch, the ramus marginis obtusi, and the apex. The diminution of clearance of this iso tope was most marked in the basal region, and imp roved progressively toward the apex. Clearances were also decreased in the basal regions just anterior and posterior to this zone.

The weight of the ischemic zone, as defined by the Rb clearance technique, was approxi matelv half of that outlined in other studies by injection of dye into the distal end of the occl.uded circumflex artery. Th.is implies that the marginal zone of the territory supplied by the left circumflex coronary artery must receive a dual blood supply. Also, the Rb
86
clearance in the ischemic zone exceeds the es timates of collateral flow l)rovided by simul taneously measured ietrogracle flows. This was true despite the facts that (a) actual blood flows must exceed the measured R clear ances, since extraction is never complete, and (b) retrograde flows overestimate the true value for interarterial collateral flow. When the interarterial collateral flow is drained away by leaving the low resistance cannula system uriclamped during the isotope inf u sion, the Rb
86
clearance is not appreciably af fected in the marginal zone and is reduced by 50 to 60 per cent in the central and basal Portions of the ischemic region. rphese find ings signify that an appreciable circulation must be provided by vessels which communi cate with the capillary beds within the ische inic zone anc1, therefore, would contribute to the measured retrograde flow to only a neg ligible extent.
Influence of Syrosingopine on the Cardiovascular Response to Acute Hypoxemia and Exercise
Authors: CHIDSEY CHARLES A. , FRYE ROBERT L. , KAHLER RICHARD L. , BRAUNWALD EUGENE
Published: June 2012

Large parenteral doses of a rauwolfia alkaloid, syrosiiigopine, administered to normal volunteers, although inducing a consistent reduction in pulse rate, did not interfere with the increase in cardiac output resulting from acute hypoxemia and exercise. The physiological and pharmacological implications of these observations are discussed.
Examination of the Relationship of Renin Release to Hypertension Produced in the Rabbit by Renal-Artery Constriction
Authors: PEART W. S. , ROBERTSON J. I. S. , GRAHAME-SMITH D. G.
Published: June 2012

Plasma samples taken from the renal veins of rabbits hypertensive following renal-artery constriction were examined for evidence of increased renin content. No increase in the activity of the renal-vein samples was found as compared with plasma obtained from other sites in these rabbits, or with samples taken from unoperated animals. By contrast, renin infused into the renal veins of rabbits to give comparable elevation of the arterial pressure was, in all cases, detected. The experimental findings are discussed in relation to current views of the role of renin in experimental hypertension in the rabbit.
Detection and Assessment of Mitral Regurgitation by Left Atrial Indicator-Dilution Curves
Authors: NEWCOMBE CHARLES P. , SINCLAIR JOHN D. , DONALD DAVID E. , WOOD EARL H.
Published: June 2012

Indicator-dilution curves were recorded simultaneously from the left atrium and the femoral artery during injections of indocyanine green into the left ventricle in normal dogs and in dogs with chronic mitral regurgitation. A study was made-without the use of thoracotomy-of the effect of the following factors on the amount of early appearing indicator detected in the left atrium: (a) the timing of the injection of indicator in relation to the cardiac cycle, (b) the position of the injecting catheter in the left ventricle, and (c) the position of the sampling catheter in the left atrium. It was found that the time and site of the injection into the left ventricle had little effect on the amount of early appearing dye detected in the left atrium and that, although the position of the sampling catheter in the left atrium was important, reproducible results were attained when the sampling site was restricted to a region in close proximity to the mitral valve. A close correlation was demonstrated between the volume of regurgitation determined independently on a hydraulic basis and the volume estimated from the fraction of early appearing indicator detected in the left atrium. It is concluded that further work with this upstream-sampling technique is justified in order to study its possibilities as a practical method for detecting and quantitating mitral regurgitation in human beings.
A Major Pitfall in the Interpretation of "Central Blood Volume"
Authors: MCINTOSH HENRY D. , GLEASON WILLIAM L. , MILLER D. EDMOND , BACOS JAMES M.
Published: June 2012

During reactive hyperemia of the legs of normal subjects, the "central blood volume"
increased
569 ml. when measured from a hrachial arterial sampling site but
decreased
144 ml. when measured from the femoral artery. This study demonstrates that changes occurring within the peripheral arterial system can profoundly influence "central blood volume" measurements which are made from a peripheral arterial sampling site. Failure to recognize the inconstancy and the potential magnitude of the arterial contribution is a major pitfall in the interpretation of the calculated "central blood volume." It is suggested that changes in either arterial volume or arterial flow distribution may alter the "central blood volume" but that the distribution effect is the more probable cause of the changes seen in this study. Alterations in "central blood volume," which result from changes within the peripheral vasculature, cannot be readily distinguished from those caused by changes in the volume of blood in the heart and lungs. Peripheral effects can be avoided if the indicator is injected into the right auricle and sampling is done from the root of the aorta.
Factors Modifying Cyclopropane-Epinephrine Cardiac Arrhythmias
Authors: DRESEL PETER E. , SUTTER MORLEY C.
Published: June 2012

Constantly coupled bigeminal rhythm of long duration induced by infusion of epinephrine into cyclopropane-anesthetized dogs may be converted to multifocal ventricular tachycardia by increasing the blood pressure without changing the infusion rate. Multifoeal arrhythmia may be converted to bigerniny or to sinus rhythm by decreasing the blood pressure but is not converted to ventricular fibrillation by an increase in systemic pressure. Stimulation of the peripheral end of either vagus can convert bigerniny to normal rhythm or increase the coupling interval. Multifocal ventricular tachycardia is converted to sinus rhythm or to bigeminy by stimulation of the vagus. The vagal effect, which is blocked uniformly by atropine, also may be demonstrated when the atrial rate is maintained constant. Vagal stimulation does not increase the threshold dose of epinephrine necessary for induction of ventricular fibrillation. It is concluded that multifocal ventricular tachycardia is due to a mechanism similar to that causing bigeminy, which was shown previously not to be due to the emergence of a focus of increased ventricular automaticity. Both of these arrhythmias probably originate in the bundle of His and differ fundamentally from ventricular fibrillation.
Effect of Unilateral Pulmonary Artery Obstruction on Circulatory Dynamics in Dogs with Chronic Atrial Septal Defects
Authors: AMORIM DALMO DES. , MARSHALL HIRAM W. , DONALD DAVID E. , WOOD EARL H.
Published: June 2012

Determinations of pressure, blood flows, and calculated pulmonary vascular resistance were made prior to and during acute individual occlusion of the right and left main branches of the pulmonary artery in random sequence in eight anesthetized, closed-chest dogs witn chronic atrial septal defects. Similar observations were made with occlusion of only the left pulmonary artery in three additional dogs. Obstruction of the pulmonary artery to one lung was immediately followed by a rise in systolic pressure in the right ventricle and pulmonary artery proximal to the obstruction, from an average normal value of 33.1 mm. Hg to an average value of 40.9 mm. Hg (range 32 to 47). This change was not associated with demonstrable systematic effects on right atrial or systemic arterial pressure or on the systemic blood flow.

As would be expected, the average calculated ratio of pressure to flow (vascular resistance) across the unoccluded lung was elevated during the obstruction. The resistance value during the occlusion, however, was less than the estimated pressure/flow ratio for this same lung, based on the measurements made prior to the occlusion. This apparent effective decrease in vascular resistance of the unoccluded lung is probably related to dilation of the pulmonary vessels as a result of an increase in intravascular pressure caused by the sudden removal of approximately half of the pulmonary vasculature from the circulation.

In spite of the elevation in right ventricular systolic pressure, occlusion of the left pulmonary artery was associated with a slight increase in pulmonary blood flow and a definite increase in the magnitude of the left-to-right shunt across the atrial septal defect, whereas no systematic effects were obtained during obstruction of the right branch in association with the same approximate levels of right ventricular systolic pressure. These data are regarded as further evidence that the preferential shunting of blood from the right lung in the presence of an atrial septal defect of the secundum type is primarily due to the anatomical relation between the opening of these vessels into the left atrium and the position of the defect in the atrial septum. Furthermore, they emphasize the importance of dynamic factors, related to the manner, site, and direction in which the pulmonary venous blood drains into the left atrium, as important determinants of the left-to-right shunt via such defects.
Controlled Cardiac Output Studies in Dogs (Part I)
Authors: Elliot ERIC C.
Published: June 2012

A method lias been presented whereby a semiquantitative estiTiiation of the coronary flow in dogs can be made (within certain experimental limits) by means of a regression equation based on the relationship that coronary flow appears to bear to the product of mean arterial blood pressure times heart rate. The data, from which the regression equation was derived, were obtained by means of the utilization of the "complete right-heart bypass preparation" in seven dogs. The equation for the prediction of coronary return was tested in an additional six dogs, using the "complete right-heart bypass preparation" and the results showed that, if the value for the estimated coronary return were added to the value for caval return, the resultant sum would give a significantly better estimate of the cardiac output than if the value for caval flow only were used as the index.
Interday variation and effect of transportation on indirect blood pressure measurements, plasma endothelin-1 and serum cortisol in Standardbred and Icelandic horses
Authors: Söder Josefin , Bröjer Johan T , Nostell Katarina EA
Published: June 2012

Background

Systemic hypertension is a prominent feature in humans with metabolic syndrome (MS) and this is partly caused by an enhanced endothelin-1 (ET-1) mediated vasoconstriction. There are indications that systemic hypertension might be a feature in equine metabolic syndrome (EMS) but if ET-1 is involved in the development of hypertension in horses is not known. Increased levels of cortisol have also been found in humans with MS but there are no reports of this in horses. Before blood pressure, plasma ET-1 and serum cortisol can be evaluated in horses with EMS, it is necessary to investigate the interday variation of these parameters on clinically healthy horses. The aims of the present study were therefore to evaluate the interday variation and influence of transportation on systemic blood pressure, plasma ET-1 and serum cortisol in healthy Standardbred and Icelandic horses, and to detect potential breed differences.

Methods

Nine horses of each breed were included in the study. Blood pressure was measured and blood samples were collected between 6 and 9 am on two separate days. Eight of the horses (four of each breed) were transported to a new stable were they stayed overnight. The next morning, the sampling procedure was repeated.

Results

The interday variation was higher for plasma ET-1 (37%) than for indirect pressure measurements (8-21%) and serum cortisol (18%). There were no differences in systemic blood pressure between the two breeds. The Icelandic horses had significantly lower serum cortisol and significantly higher plasma ET-1 concentrations compared to the Standardbred horses. Plasma ET-1 was significantly elevated after transportation, but systemic blood pressure and serum cortisol did not differ from the values obtained in the home environment.

Conclusions

Indirect blood pressure, plasma ET-1 and serum cortisol are of interest as markers for cardiovascular dysfunction in horses with EMS. The elevated plasma ET-1 concentrations recorded after transportation was likely caused by a stress response. This needs to be considered when evaluating plasma ET-1 in horses after transportation. The differences detected in plasma ET-1 and serum cortisol between the two breeds might be related to differences in genetic setup, training status as well as management conditions.
‘ people are going to want to know what really went down’: Cloverfield and the return to innocence in post-9/11 America
Authors: Overpeck Deron
Published: June 2012

This article reads the American giant-monster film Cloverfield (Matt Reeves, 2008) as part of a national narcissistic response to the terrorist attacks in New York City in 2001 on September 11. Al Qaeda’s deadly assault has been reconfigured from a geopolitical act of violence
into an opportunity for an intrepid if callow young man to rescue his lost lover; the gigantic, rampaging creature and its city-wide battle with the military is almost a distraction to his quest. Inspired by Gojira (Inoshiro Honda, 1956), Cloverfield presents an unknowable, unpredictable,
oft-unseen monster – the perfect villain for a horror film in the age of terrorism.
Birth by Cesarean Delivery and Failure on First Otoacoustic Emissions Hearing Test
Authors: Smolkin Tatiana , Mick Orna , Dabbah Maisam , Blazer Shraga , Grakovsky Galina , Gabay Noah , Gordin Arie , Makhoul Imad R.
Published: June 2012

BACKGROUND:

Neonatal hearing screening occasionally fails. We noticed that infants born by cesarean delivery (CD) appeared to fail the first otoacoustic emissions (OAE) test more frequently than infants delivered vaginally (VD). This might increase maternal anxiety. We aimed to evaluate the influence of mode of delivery on failure to pass the first OAE.

METHODS:

Overall, 1653 infants of >35 weeks’ gestation were evaluated. OAE was performed before discharge. Perinatal-neonatal variables and results of OAE were recorded retrospectively.

RESULTS:

Compared with VD infants, CD infants had lower gestational age and 1-minute Apgar, more small for gestational age (SGA), and earlier age at first OAE. Univariate analysis: CD, male gender, gestational age 35 to 37 weeks, birth weight ≤2500 g, SGA, and younger age at first OAE were significantly associated with failed first OAE. In infants weighing 2501 to 4000 g, CD infants had 3-fold higher rates of failed first OAE in comparison with VD infants (20.7% vs 7.1%) before 48 hours of age. In the multivariate analysis, variables independently significantly associated with failed first OAE were male gender (odds ratio [OR] 1.42 [1.02–1.98]), CD (emergency CD: OR 3.18 [2.21–4.57], elective CD: OR 3.32 [2.04–5.42]), age 12 to 23 hours at first OAE (OR 3.1 [2.1–4.58]) and SGA (OR 2.2 [1.15–4.28]).

CONCLUSIONS:

CD infants had significantly higher failure rates on first OAE. We speculate that CD is accompanied by retained fluid in middle ear which may impair neonatal hearing. The timing of first OAE after CD should preferably be postponed beyond 48 hours of age to improve OAE passage and minimize maternal anxiety and costs.
Numerical and experimental study of heat transfer in gas-solid flow: Particle cooling
Authors: El-Behery S. M. , El-Askary W. A. , Hamed M. H. , Ibrahim K. A.
Published: June 2012

Heat transfer in gas-solid two-phase flow is investigated numerically and experimentally. The numerical computations are carried out using four-way coupling Eulerian-Lagrangian approach. The effects of particle rotation and lift forces are included in the model. The gas-phase turbulence is modeled via low Reynolds number k-ε turbulence models. The SIMPLE algorithm is extended to take the effect of compressibility into account. The experimental study is performed using crushed limestone to simulate the solid phase. The effects of Reynolds numbers, particles size and temperature on the pressure drop and the temperature of the phases are investigated. The model predictions are found to be in a good agreement with available experimental data for high speed gas-solid flow and present experimental data for low speed flow. The present results indicate that heat transfer in gas solid flow can be modeled using ideal gas incompressible flow model at low conveying speed, while for high speed flow, a full compressible model should be used.
Contribution to mathematical modelling of charging and discharging of the seasonal heat storage tank
Authors: Böszörményi L. , Šiváková E.
Published: June 2012

The seasonal heat storage tank is the most important component of the SDH system, which allows significant increase in the share of solar energy in heat supply in comparison with conventional solar systems with short-term accumulation of heat. The adverse impact of their investment sophistication on competitiveness may be compensated by the increased use. For example: Administrative cooperation with heat pump allows increasing the accumulation capacity of the seasonal heat storage tank. Such cooperetion causes the direct use of heating energy and the accumulation of cooling energy produced by heat punp in the final stage of the heating period. It can be used to remote cooling supplied buildings. Experimentation on mathematical models is possible to obtain valuable insights about the dynamics of the processes of charging and discharging in the seasonal storage tank and subsequently used in the design, implementation and operation.
Aging of ZnS:Mn ALE ac thin‐film electroluminescent devices
Authors: Soenen B. , Neyts K. , Van den Bossche J. , De Visschere P.
Published: June 2012

Abstract— The aging behavior of ZnS:Mn ACTFEL devices, driven with asymmetrical voltage waveforms, was analyzed. Samples were aged with asymmetrical waveforms, so a time‐averaged electric field exists in the phosphor layer during operation. Transient measurements were used to determine the voltage polarity dependence of the aging process. While with symmetrical aging and waveforms which cause a positive time‐averaged field the positive polarity is mainly affected, a negative time‐averaged field affects both polarities. A simple model to explain these measurements is proposed.
Terbium‐doped nanocrystalline phosphors
Authors: Goldburt E. T. , Bhargava R. N.
Published: June 2012

Abstract— Terbium‐doped ZnS and Y2O3 nanocrystalline phosphors were prepared using room‐temperature organometallic synthesis and modified sol‐gel processing. The photoluminescent and photoluminescent‐excitation spectra of these materials reveal characteristic Tb3+ emission (d5−f7 transition). The intensities of the Tb3+ emission in standard terbium‐doped LaOBr phosphor and terbium‐doped nanocrystalline yttria phosphor are compared. To date, the best photoluminescent efficiency of the nanocrystalline phosphors excited at 254 nm is about 50% of that of the standard phosphor.
Beyond Prevention: Promoting Healthy Youth Development in Primary Care
Authors: Taliaferro Lindsay A. , Borowsky Iris W.
Published: June 2012

Training primary care providers to incorporate a youth development approach during clinical encounters with young people represents an opportunity to integrate public health into primary care practice. We recommend that primary care providers shift their approach with adolescents from focusing on risks and problems to building strengths and assets. Focusing on strengths rather than problems can improve health by fostering resilience and enhancing protective factors among adolescents. A strength-based approach involves intentionally assessing and reinforcing adolescents' competencies, passions, and talents, as well as collaborating with others to strengthen protective networks of support for young people. Training programs should incorporate interactive strategies that allow clinicians to practice skills and provide tools clinicians can implement in their practice settings.
Testing and Perforating in the HPHT Deep and Ultradeep Water Environment
Authors: Wendler C. , Scott M.
Published: June 2012

The US Gulf of Mexico is one of the few regions in the world where wells are completed in the deepwater Miocene and Lower Tertiary reservoirs. These deepwater plays have required constant technological improvement to equipment service capabilities in order to maintain integrity in the 30,000-psi environments and minimize risks. Although capable tools and guns have been developed, continuous assessing of reliability still remains vital in the exploratory processes.

Testing for production assessment in deep and ultra-deep water is critical, and when target reservoirs produce heavy oil, gas and condensate, or are in HP/HT environments, planning safe tests with risk mitigation that can gather high-quality data is paramount. Because of the high rig rates for deep-water operations, prolonged periods of low temperature and heat loss that can affect production or enable hydrate formation and other environmental challenges cannot be ignored. Fluid volumes and water depths can increase well-control time and expense. Also, since well tests are conducted from mobile vessels, alarm and subsea equipment philosophies are critical to success, and well-test string configurations must be flexible yet control well safety.

Obviously, all issues must be understood for the program plan to anticipate the potential challenges. The purpose of this paper is to explore these issues as well as discuss mitigation methodologies. The considerations, merits, and limitations of various solutions will be considered. Lessons learned from actual cases will compare the consequences of inadequate preparation to the benefits of proper design.

This paper explains why and how the methods and equipment suggested should be used and will include:

DP vessel testing Well integrity at extreme depths and pressures Functional pressure-operated tool windows Coiled tubing Cushion and mud-type criteria Hydrate prevention Perforating strategies.
Evaluation of Thermal/Solvent Applications with and without Cold Heavy Oil Production with Sand (CHOPS)
Authors: Rangriz Shokri A. , Babadagli T.
Published: June 2012

Typical recovery factor for conventional heavy oil primary production has been reported about 1-5% of original oil in place. The recovery factor of cold production can be improved up to 5-20% using other techniques, Cold Heavy Oil Production with Sand (CHOPS) being one of them(1,2). CHOPS is a deliberate sand production with oil in unconsolidated sand reservoirs with an oil viscosity of 500 to 15000 cP. It is believed that sand production increases oil rate and makes the well to remain at the economic limit of cold production. Based on field observations and laboratory experiments, it creates cavity and wormholes at least around the well and possibly far further in the reservoir. This wormhole pattern not only increases the oil production rate, but also alters reservoir characteristics in a dramatic fashion.

Based on current literature, CHOPS offers a very low OPEX and CAPEX compared to thermal methods and surface mining. During CHOPS, many of the important properties of the reservoir change. Mathematically, it means a need for predictive and dynamic models and simulations for CHOPS. Unfortunately, due to dynamic changes of reservoir properties, no valid model is available to simulate CHOPS production. But, it is believed, after certain sand production period and in the beginning of subsequent enhanced oil recovery processes, these dynamic changes become very rare. Hence, a dual porosity approach can be practically employed for post-CHOPS studies.

In this paper, we present a partial dual porosity modeling approach with selective wormhole patterns, depending on the well perforations and geological properties. First, wormhole patterns are generated and introduced into a static model. It is assumed that wormhole properties are a function of its radius and it can be controlled along with its length and pattern, which facilitates history matching process. After validation of the model with available field data, different post-CHOPS scenarios are studied. Proposed simulation approach to create post-CHOPS is flexible and can be applied in both black-oil and compositional simulators.