Modulation by prostaglandin synthesis inhibitors of the action of exogenous angiotensin II on glomerular ultrafiltration in the rat.

We studied the effects of angiotensin II (A II) infusion, with and without inhibition of prostaglandin (PG) synthesis, on the determinants of glomerular ultrafiltration in 27 plasma volume-expanded Munich-Wistar rats. The effects of PG inhibition alone and infusion of vehicle alone also were investigated. With a pressor dose of A II single nephron (SN) GFR and total GFR did not change significantly, despite declines in both glomerular plasma flow rate (QA) and the ultrafiltration coefficient (Kf), due to an offsetting rise in the transcapillary hydraulic pressure difference (deltaP). Afferent and efferent arteriolar resistances (RA and RE) increased by approximately 100% above control during A II infusion. Inhibition of PG synthesis alone and infusion of vehicle alone similarly failed to affect SNGFR and total GFR, and only slight changes occurred in the determinants of glomerular ultrafiltration in these rats. When A II infusion was accompanied by inhibition of PG synthesis, however, profound declines in SNGFR and total GFR were seen, due to further reductions in QA and 2-fold greater increases in RA and RE than occurred with the same dose of A II alone. The A II-induced fall in Kf was not affected by simultaneous PG inhibition. Thus, endogenous PGs attenuate the vasoconstrictor actions of A II on the superficial renal microvasculature and minimize changes in QA, SNGFR, and total GFR. It is likely that an interaction between A II and PG may be important in pathophysiological conditions in which endogenous A II levels are elevated.


The relation of localized myocardial warming to changes in cardiac surface electrograms in dogs.

We studied the relationship of the size and severity of alteration of recovery properties in localized areas to changes in cardiac surface electrograms in experiments on six open-chest dogs. Alterations in recovery properties were induced thermally because size and severity of the affected area could be controlled on the basis of physical principles which were modeled. We recorded unipolar electrograms from 75 cardiac surface sites simultaneously during stimulation of atria and pulmonary conus in control periods and in the presence of warmed areas of varying sizes and intensities. Size of the areas was controlled by the diameter of an aperture through which a light source was directed. Intensity was controlled by the light source excitation voltage. Myocardial temperature was monitored with a thermistor. The QRS, STT, and QRST deflection areas were determined by computer processing and displayed as isoarea maps. Difference maps also were determined by subtracting control QRST isoarea maps from those obtained in the presence of warmed areas. QRST area difference maps were related closely to the size and severity of the thermally induced changes in recovery properties. With areas of the same size and increasing myocardial temperatures, the magnitude of the change in QRST area increased, and the gradient of contour lines between the affected and unaffected areas increased. When myocardial temperature at the center of the warmed area was kept constant and the size of the warmed area was increased, the affected cardiac surface area increased, but the number of isoarea contours remained approximately the same. These findings suggest that the change in QRST isoarea maps may be a useful indicator of lesion size when combined with an index of lesion severity such as the QRST area change in the electrogram with the maximum change. QRST areas during both activation orders were similar, suggesting that the QRST area is independent of changes in activation sequence.


Staircase in frog ventricular muscle. Its dependence on membrane excitation and extracellular ionic composition.

Staircase was studied in frog ventricle strip preparations where it was possible to alter extracellular ionic composition extremely rapidly in the diastolic interval between beats. Several findings strongly indicate that staircase in this tissue is a result of progressively increasing calcium influx per beat, rather than a beat-by-beat augmentation of an intracellular calcium pool which contributes to activation. After a steady state of force development, the very next beat could be graded, from approximately zero force to the steady state value attained during the staircase progression, by grading the calcium concentration of a new Ringer's solution switched to perfuse the muscle in the diastolic period immediately before that beat. Also, action potentials, elicited during the "quiescent" period in the virtual absence of contraction (in 0.025 mm calcium Ringer's solution), markedly increase force development and accelerate the staircase seen upon return to normal Ringer's solution. Staircase is augmented and accelerated by prior exposure of the muscle, during the quiescent period, to calcium-poor media and markedly suppressed by prior exposure to sodium-poor media. Tetrodotoxin, in a dose that markedly slows the action potential upstroke, has no effect on staircase. Finally, staircase is seen to occur during a train of depolarizations (by voltage clamp) to inside positive levels greater than the equilibrium potential for sodium. It is concluded that changes in intracellular sodium concentration will alter the staircase response and may contribute to its genesis, but that this cannot be the sole cause of staircase.


Age-related changes in Purkinje fiber action potentials of adult dogs.

To determine the effects of age on electrophysiological properties of Purkinje fibers (PF), we used standard microelectrode techniques to study PF from normal beagles of five age groups: 19.1 +/- 0.8, 63.7 +/- 2.6, 88.3 +/- 1.9, 107.2 +/- 1.6, and 132.3 +/- 4.3 months (mean +/- SE). Maximum diastolic potential (MDP) did not change over this age range. Action potential (AP) amplitude and maximum upstroke velocity of phase 0 (Vmax) attained peak values at 63.7 months and then declined. As age increased there was an increase in phase 1 repolarization, a prolongation in the time to the peak of the plateau, and a decrease in plateau height. AP duration reached a maximum at 63.7 months and thereafter remained unchanged. Fibers were superfused with the slow channel blocker, AHR-2666, and the fast channel blocker, tetrodotoxin (TTX). AHR-2666 had age-related effects on AP duration, phase 1 repolarization, plateau height, and time to the peak of the plateau. There were no age-related changes in TTX effects on phases 0--2. In another series of experiments, Purkinje fibers from dogs 23 +/- 1.2 to 106 +/- 1.4 months old were superfused with a calcium-rich solution in which Na+ was replaced by tetraethylammonium (TEA+). The resultant slow response action potentials, which are calcium dependent, showed an age-related decrease in AP amplitude, Vmax, and time to peak amplitude. When these fibers were superfused with the slow channel blocker, verapamil, there was an age-related effect on AP amplitude. Our studies indicate that in the normal aging heart, major changes occur in repolarization that appear, in the main, to result from change in the slow inward current carried by Ca2+.


Fixed coupling: different mechanisms revealed by exercise-induced changes in cycle length.

Fixed coupled ventricular premature depolarizations (VPDs) are usually considered reentrant; recent experimental models have demonstrated that parasystolic rhythms may also appear in fixed coupled patterns. To analyze the mechanisms of fixed coupled VPDs, 60 exercise tests were chosen to evaluate the response of VPD coupling intervals to changes in cycle length of the dominant supraventricular rhythm. Selection criteria included the presence of frequent, unifocal VPDs that were fixed coupled (variation less than or equal to 80 msec) at any one cycle length, with the persistence of VPDs at several different cycle lengths. Three patterns of response of coupling intervals to changes in cycle length were noted: 1) 32 patients with a direct linear relation (r greater than or equal to 0.9) of coupling intervals to cycle length; 2) 16 patients with coupling intervals fixed, independent of cycle length; and 3) 12 patients with no consistent relation over a wide range of cycle lengths. Two patients in group 2 and four in group 3 fulfilled criteria for parasystole with interectopic intervals that remained constant at different cycle lengths. These results suggest that VPDs in group 1 are reentrant, while some patients with group 2 or 3 responses have evidence for parasystolic rhythms. We conclude that 1) fixed coupling of VPDs is not diagnostic of reentry, and 2) changes in cycle length induced with exercise may be useful in the analysis of mechanisms of VPDs.


Abolition and modification of reentry within the His-Purkinje system by procainamide in man.

The effects of intravenous procainamide infusion of 10--14 mg/kg body weight (i.e., 750 mg) of procainamide (PA) on reentry within the His-Purkinje system (HPS) were studied in 13 patients using His bundle electrograms and ventricular extrastimulus method. PA abolished reentry in eight patients (group 1) and decreased the width of reentry zone in the remaining five (group 2). At comparable S1S2 intervals, the S2H2 intervals after PA were longer than control in all patients. In group 1 patients, after PA, reentry did not occur even at S2H2 intervals that were significantly longer than control critical S2H2 intervals. In two of eight patients in group 1, PA abolished reentry by converting unidirectional block into bidirectional block in the antegrade limb (right bundle) of the reentry circuit. In the remaining six patients reentry was abolished because of consistent retrograde block of S2 impulse at some point between the site of stimulation and the His bundle recording site. In group 2, reentry was initiated after PA at approximately the same S1S2 intervals as in control, but required significantly longer S2H2 intervals; in these patients the zone of reentry was shortened due to increase in effective refractory period of the ventricular muscle. PA significantly increased the functional refractory period of HPS and the effective refractory period of ventricular muscle. The results of this study differ from the previously reported effects of lower concentrations of PA which facilitated reentry within the same circuit. We conclude that the effects of PA on reentry are dose-related and can both facilitate and suppress reentry, depending on critical changes in conduction and refractoriness of the HPS.


Disparate electrophysiological alterations accompanying dysrhythmia due to coronary occlusion and reperfusion in the cat.

The electrophysiologic changes associated with dysrhythmias induced by coronary occlusion and by subsequent reperfusion were characterized with six complimentary approaches in chloralose-anesthetized cats (n = 57) with proximal occlusion of the left anterior descending (LAD) coronary artery. Occlusion led to reproducible ventricular dysrhythmia which abated in 35 minutes. The electrophysiologic effects of reperfusion initiated at this time could be studied. Simultaneous bipolar electrograms (epi-, myo- and endocardial) from ischemic and normal zones were analyzed by computer. Before the onset of the dysrhythmia induced by occlusion, conduction was markedly slowed, with dV/dt decreasing to 34% +/- 6% of control and conduction time (endo- to epicardial activation) prolonged to 328 +/- 77% of control. However, these values returned toward normal with reperfusion, even though it also consistently induced dysrhythmia. The idioventricular escape rate (determined by intense vagal stimulation) was 62 +/- 6 beats/min during the dysrhythmia induced by occlusion (equal to control), but increased during the reperfusion dysrhythmia to 188 +/- 12 beats/min. The occlusion dysrhythmia was exacerbated, but the reperfusion dysrhythmia was suppressed by rapid atrial pacing. The refractory period progressively shortened after occlusion and remained decreased during early reperfusion. Thus, increased conduction time through myocardial and epicardial regions, asynchronous depolarization and shortening of the refractory period accompanied dysrhythmia induced by occlusion. In contrast, the dysrhythmia induced by reperfusion was characterized by normal conduction time, through myocardial regions with continued significant epicardial delay, overdrive suppression, synchronous depolarization and a high idioventricular rate.


Multicentric origin of the atrial depolarization wave: the pacemaker complex. Relation to dynamics of atrial conduction, P-wave changes and heart rate control.

In studies to ascertain the basis of dynamic changes in the P wave, bipolar epicardial potentials were recorded from multiple atrial electrodes in dogs. One hundred to 120 activation times were displayed by a digital computer and used to construct atrial isotemporal activation sequence maps. Changes in heart rate or beat-to-beat cycle length were induced by vagal stimulation or infusion of autonomic mediating drugs. Changes in cycle length were associated with dynamic changes in the atrial activation sequence and surface P-wave. A conspicuous finding was that epicardial atrial depolarization began at three widely separated locations. These three points were consistently present in all animals and were generally located at the 12, 3, and 6 o'clock positions of the superior vena cava-right atrial junction. The dynamic changes in P waves and atrial activation sequence which accompanied the changes in cycle length were due to sudden shifts in the point of earliest activity between the three early sites. Asymmetric atrial depolarization with more rapid conduction along the crista terminalis, superior interatrial band, and pectinate muscles was present in all dogs. Although the anisotropic atrial geometry played an important role in the asymmetric conduction, the widely distributed onset of activity contributed significantly to the uneven spread. The multiple points of origin of the atrial wavefront might be explained by either a trifocal, distributed pacemaker or the epicardial exits of three specialized pathways conducting an impulse emanating from a single focus. These data explain the dynamic variation in P-wave morphology in normal hearts and also imply a relationship between the altered origin of atrial depolarization, atypical P waves, brady- or tachyarrhythmias, and heart rate control.


Echocardiographic evaluation of intracardiac pacing catheters: M-mode and two-dimensional studies.

Thirty patients with right ventricular (RV) and 15 with coronary sinus (CS) pacing catheters were studied by M-mode echocardiography. RV catheters, detected in 23, appeared as linear echoes in the right ventricle during mitral valve recordings in 12, adjacent or superimposed on the tricuspid valve (TV) in 14, and immediately anterior to aortic root and pulmonary valve echoes in two with a redundant loop in RV outflow. In three with complete heart block, prominent systolic anterior movements of the TV occurred when atrial systole coincided with ventricular systole, probably due to catheter-induced TV "buckling" or exaggerated TV annular motion. Catheter echoes mimicked TV recordings in three, since its motion pattern was similar, although delayed and mimicked prolapsing right atrial myxomas in two because of multilayered complexes behind TV, while reverberations cluttering the left ventricle simulated structural echoes present in that cavity. CS catheters, detected in 14 as linear echoes in the area of atrial septum recorded behind the TV, showed typical small humps in late diastole/early systole. Cross-sectional echocardiography with a mechanical sector scanner demonstrated RV catheters at the RV apex in five of seven patients, while CS catheters were detected near the base of the atrial septum in three of five patients. Echocardiography has the potential to localize pacing catheters which are occasionally difficult radiologically or electrocardiographically. Failure to recognize catheter echo patterns may result in errors in echocardiographic interpretation.


Physiologic correlates of echocardiographic pulmonary valve motion in diastole.

It has been shown that the echographic motion of the posterior aortic wall in diastole is closely related to the underlying left atrial events, possibly due to the anatomical proximity of the two structures. We observed that the pulmonary artery shares a similar close anatomical relationship with the left atrium. The present study in 55 consecutive patients with adequate echocardiographic recordings of the aortic root and the pulmonary valve demonstrates that the diastolic waveforms of the pulmonary valve and the posterior aortic wall are nearly identical in early diastole. The pulmonary valve e-f slope correlated with the posterior aortic wall O-R slope (r = 0.95) and the S2-f interval (second heart sound to f on the pulmonary valve) correlated closely with the S2-R interval (second heart sound to R on the posterior aortic root) (r = 0.94)). No significant correlation was found between the pulmonary valve e-f slope and the pulmonary artery pressures. The presence and amplitude of the maximum "a dip," on the other hand, correlated with the presence of pulmonary hypertension, with some notable exceptions. In addition, the "a dip" on the pulmonary valve and the depth of the A wave on the posterior aortic wall were significantly correlated (r = 0.85). It appears that the "a dip" on the pulmonary valve is influenced by dual mechanisms: pressure differences between the pulmonary artery and the right ventricle in late diastole and the left atrial events. Thus, the early diastolic waveform of the pulmonary valve, like the posterior aortic wall waveform, may primarily reflect underlying left atrial events and is not a measure of pulmonary artery pressure. The late diastolic waveform "a dip" has a dual mechanism, related in part to the underlying left atrial events, and also reflecting the instantaneous pressure differences across the pulmonary valve following atrial systole.


Recommendations regarding quantitation in M-mode echocardiography: results of a survey of echocardiographic measurements.

Four hundred M-mode echocardiographic surveys were distributed to determine interobserver variability in M-mode echocardiographic measurements. This was done with a view toward examining the need and determining the criteria for standardization of measurement. Each survey consisted of five M-mode echocardiograms with a calibration marker, measured by the survey participants anonymously. The echoes were judged of adequate quality for measurement of structures. Seventy-six of the 400 (19%) were returned, allowing comparison of interobserver variability as well as examination of the measurement criteria which were used. Mean measurements and percent uncertainty were derived for each structure for each criterion of measurement. For example, for the aorta, 33% of examiners measured the aorta as an outer/inner or leading edge dimension, and 20% measured it as an outer/outer dimension. The percent uncertainty for the measurement (1.97 SD divided by the mean) showed a mean of 13.8% for the 25 packets of five echoes measured using the former criteria and 24.2% using the latter criteria. For ventricular chamber and cavity measurements, almost one-half of the examiners used the peak of the QRS and one-half of the examiners used the onset of the QRS for determining end-diastole. Estimates of the percent of measurement uncertainty for the septum, posterior wall and left ventricular cavity dimension in this study were 10--25%. They were much higher (40--70%) for the right ventricular cavity and right ventricular anterior wall. The survey shows significant interobserver and interlaboratory variation in measurement when examining the same echoes and indicates a need for ongoing education, quality control and standardization of measurement criteria. Recommendations for new criteria for measurement of M-mode echocardiograms are offered.


The echocardiographic profile of patients after Mustard's operation.

In order to establish an echocardiographic profile of patients with simple transposition after Mustard's operation, we examined the M-mode records of 10 patients who were found to be free of significant abnormalities at follow-up cardiac catheterization. When compared with established normals, right ventricular wall thicknesses and cavity dimensions were increased, while left ventricular wall thicknesses and cavity dimensions fell below the mean. The wall thicknesses, cavity dimensions and ratios of right ventricular preejection period/ejection time and left ventricular preejection period/ejection time were appropriate for the physiologic role of the ventricles rather than their morphologic identity. In each patient, a portion of the intra-atrial baffle was identified behind the pulmonary root. There was variation in baffle position and baffle mobility within the group, as well as in individual echograms. A variety of valve motion abnormalities were noted; these included diastolic flutter of the atrioventricular valves in all 10 patients and systolic anterior motion of the mitral valve in six patients. Paradoxical septal motion was found in nine patients. Although only minimal or no left ventricular outflow gradients were found at catheterization, nine patients had narrowing of the left ventricular outflow tract, 10 had systolic flutter of the pulmonary valve and eight had early partial closure of the pulmonary valve. The finding of a large number of echocardiographic abnormalities in a group of patients with good hemodynamic results suggests that these echocardiographic features are to be expected after Mustard's opration. Furthermore, the reversal of the physiologic role of the ventricles must be considered when interpreting the echocardiographic dimensions and systolic time intervals.


Lung biopsy in congenital heart disease: a morphometric approach to pulmonary vascular disease.

Fifty patients with congenital heart disease, ages 2 days-30 years (median 12 months) at cardiac surgery, underwent lung biopsy to assess pulmonary vascular disease (PVD). Twenty-six had ventricular septal defects (VSD), 17 d-transposition of the great arteries (D-TGA), and seven, defects of the atrioventricular canal (AVC). Quantitative morphologic data was correlated with hemodynamic data. Three new grades of PVD were observed. Abnormal extension of muscle into peripheral arteries (grade A) was found in all patients; all had increased pulmonary blood flow. In addition, 38 of 50 patients had an increase in percentage arterial wall thickness (grade B); this correlated with elevation in pulmonary artery (PA) pressure (r = 0.59). Another 10 of 50 patients had, in addition to A and B, a reduction in the number of small arteries (grade C); nine of 10 were patients with elevated PA resistance greater than 3.5 mu/m2 (P less than 0.005). All three patients with Heath-Edwards changes of grade III or worse also had grade C. Reduction in peripheral arterial number probably precedes obliterative PVD and may identify those patients in whom, despite corrective surgery, PVD will progress.


Systolic time intervals in children: normal standards for clinical use.

Systolic time intervals were measured in 253 normal children, with careful attention to precise recording and measuring techniques, to derive regression equations which could be used as reliable standards for clinical assessment of left ventricular performance in this age group. Using stepwise regression analysis, a highly significant correlation was found for electromechanical systole (QS2) and for left ventricular ejection time (LVET) with heart rate alone in both males and females, and age was not found to be a relevant variable. Similarly, for the preejection period (PEP) in males, heart rate was the only relevant variable. PEP in females showed a small but significant influence of age in addition to heart rate; in practice, this small influence can be neglected. Regression equations relating each of the systolic time intervals to heart rate alone were therefore derived for clinical use. The PEP/LVET ratio was found to be only weakly correlated with heart rate in males and with age in females, and in practice can be considered to be independent of these variables. The mean value of the PEP/LVET ratio and its standard deviation (0.30 +/- 0.04) can therefore be used for all children. We found that satisfactory recording of systolic time intervals can be obtained with little difficulty in almost all children using the techniques described. The method is therefore practical for clinical use in children, as it is in adults, and the normal standards derived in this study can serve as a reliable basis for its application.


Detection of serum cardiac myosin light chains in acute experimental myocardial infarction: radioimmunoassay of cardiac myosin light chains.

To develop a more specific plasma test for myocardial infarction, antibodies specific for cardiac myosin light chains (CM-LC) were elicited that showed less than 3% cross-reactivity with skeletal muscle light chains. These antibodies were used to develop a radioimmunoassay for CM-LC that had a sensitivity of 20 ng (+/- 4 SD; P less than 0.001). Normal dog plasma showed no measurable concentrations of CM-LC (n = 6). Plasma samples from 10 dogs with experimental myocardial infarction produced by persistent left anterior descending coronary artery (LAD) occlusion were obtained at 0, 2, 4, 6, 24, 48 and 72 hours. CM-LC were first detectable in all 10 animals 6 hours after occlusion (97.98 +/- 14 ng/ml [mean +/- SEM]; P less than 0.001). Maximal CM-LC levels were usually obtained between 24 and 48 hours. Sham-operated open chest dogs (0--48 hours, n = 3) showed no measurable CM-LC in the plasma samples. Another group of 10 dogs were subjected to 5 hours of LAD occlusion, followed by reperfusion. In four dogs, CM-LC were detectable as early as 1 hour after reperfusion (81.88 +/- 37.75 ng/ml serum). Sera from all 10 dogs showed elevated levels of CM-LC (199.75 +/- 24.0 ng/ml) by 24 hours. Peak CM-LC concentrations were obtained in five dogs at 24 hours (247.0 +/- 35.28 ng/ml) and in another dog at 120 hours (245 ng/ml). Histochemical infarct size was determined to be 0.5--10% of the left ventricular mass at seven days by triphenyltetrazolium chloride staining. The specificity and sensitivity of this radioimmunoassay for detection of CM-LC, unique proteins to the heart, may be valuable in the diagnosis of myocardial infarction.


Early imaging of experimental myocardial infarction by intracoronary administraion of 131I-labelled anticardiac myosin (Fab')2 fragments.

We examined the feasibility of early imaging of myocardial infarcts by intracoronary injection of 131I-labelled cardiac myosin-specific antibody (Fab')2. The left anterior descending coronary artery was occluded for 5 hours by a balloon catheter introduced through the carotid artery in 12 dogs. The catheter was withdrawn and 1 mCi 201Tl was injected intravenously and 500 muCi of 131I antibody were injected into the main left coronary artery. Six of these animals demonstrated evidence of myocardial infarction by ECG and subsequent triphenyl-tetrazolium chloride staining, while the others did not. In each of the infarcted animals, in vivo scintograms one-half hour after injection of isotope showed uptake of 131I in the anteroapical region of the heart corresponding to the region of absent 201Tl uptake. This relationship was confirmed in the excised hearts and in heart slices. In slices, 131I uptake corresponded to regions that did not stain with triphenyltetrazolium chloride. In the six animals that did not show evidence for infarction after coronary occlusion, uptake of 131I was not demonstrated, either in vivo or in excised specimens. In four additional dogs subjected to the same procedure, 125I-labelled (Fab')2 from nonimmune IgG was injected simultaneously into the left main coronary artery with 131I-labelled canine myosin-specific antibody (Fab')2. The ratio of uptake between infarct center and normal tissue was 34.3 +/- 1.5 (mean+/-SEM) for the specific antibody fragment as contrasted to 6.6+/-0.4 for the nonimmune IgG fragment, indicating that intracoronary injection does not favor nonspecific sequestration of protein in regions of infarction. Thus, the intracoronary administration of myosin-specific antibody fragments leads to early and specific one-half hour imaging of myocardial infarcts.


Myocardial infarction size from serial CPK: variability of CPK serum entry ratio with size and model of infarction.

To study the variability of the fraction of CPK released from the infarcted heart which enters the serum (serum entry ratio, or SER) with size and model of infarction, nine dogs underwent homogeneous infarctions (LAD ligation) of varying sizes, and 10 dogs underwent scattered infarctions (left coronary embolization). In homogeneous infarcts there was an inverse linear relationship of SER to infarct size (IS) (SER = -0.8514% LV + 0.345, r = 0.98). No such relationship was found for scattered infarcts. CPK Kd (exponential disappearance constant for CPK) was not significantly different in homogeneous (-0.00178 min-1) vs scattered infarcts (-0.00195 min-1). Although similar IS was produced in each (homogeneous 19.9% LV, scattered 18.4% LV) cumulative CPK serum entry (CPKr) was much lower in homogeneous (4175 mlU/ml) vs scattered infarcts (7,296 mlU/ml). SER was also much lower in homogeneous (17.7%) vs scattered infarcts (29.0%) (P less than 0.025). Cumulative CPK plateau occurred significantly later in homogeneous (15.8 hours) vs scattered infarcts (11.7 hours) (P less than 0.01). Further corrections to the serial CPK equations for IS determination are indicated. The method may not be applicable in some infarct situations, e.g., scattered infarction.


Relationship of regional myocardial perfusion to segmental wall motion: a physiologic basis for understanding the presence and reversibility of asynergy.

Experimental work has shown that even small reductions in myocardial perfusion impair contractile performance. We, therefore, studied the relationship between regional perfusion, assessed by thallium-201 scintigraphy and segmental wall motion, quantitated on biplane contrast ventriculograms, in patients with coronary artery disease. We evaluated 270 segments in 54 patients, including 27 without evidence of myocardial infarction. Most normally perfused regions (125 of 140) contracted normally, whereas those with scintigraphic defects at rest were usually asynergic (42 of 46). Surprisingly, 57% (48 of 84) of regions with exercise-induced perfusion defects were also asynergic, including 48% (25 of 52) of those in patients without myocardial infarction. In 22 patients who had intervention ventriculograms, improvement of perfusion abnormalities at rest correlated closely with reversibility of asynergy. Although there was an association between the location and severity of coronary artery stenosis and segmental wall motion, myocardial perfusion during exercise was a significantly better predictor of asynergy. These findings suggest that resting asynergy may occur even in patients without previous infarction, predominantly in regions with jeopardized perfusion. Asynergy in regions with exercise-induced perfusion abnormalities may, therefore, be an indicator of resting ischemia and may be reversible by coronary artery revascularization.


Emergency revascularization for unstable angina.

Emergency revascularization for unstable angina (defined according to criteria of the National Cooperative Study Group) was performed in 100 consecutive patients. The mean interval from onset of pain to operation was one day. Nineteen patients had single-vessel narrowing of greater than 70% of lumen diameter, 32 double-vessel obstruction and 49 triple-vessel disease. Fourteen of these patients had left main trunk obstruction. Four patients died within 30 days, three from complications of myocardial infarction. Seventeen of 96 (18%) early survivors sustained perioperative infarction. After a mean follow-up of 42 months, four late deaths and three late infarctions occurred. Postoperative angiography in 47 patients (mean interval 14 months) showed 86% graft patency. Of 92 survivors, 72 are symptom-free. Three of the four operative deaths occurred within 24 hours postoperatively; in each of these, postmortem examination confirmed a recent myocardial infarction which antedated the operation, despite the absence of new infarction in the peroperative electrocardiogram or elevation of cardiac enzymes. Results from this emergency series suggest that, although myocardium may be salvaged in some instances, in other cases infarction has already occurred and treatment might better be directed toward alleviation of acute ischemia to provide a stable period in which diagnostic studies are performed and acute myocardial infarction may be ruled out.


Ventriculographic features predictive of surgical outcome for left ventricular aneurysm.

Although clinical and hemodynamic stability predicted outcome very well when left ventricular aneurysm was electively resected in 25 patients (95% survival), more discriminate criteria were essential for 20 patients undergoing urgent operation for severe myocardial decompensation (50% survival). Three methods of ventriculographic analysis primarily sensitive to the function of the non-aneurysmal left ventricle were evaluated. These methods separated patients undergoing urgent operation into a population with high operative risk (less than 18% survival) and a population with low operative risk (greater than 82% survival). These criteria also separated 15 patients undergoing operation within three months of myocardial infarction into a group with excellent prognosis (greater than 85% survival) and a group with poor prognosis (less than 15% survival). The high operative risk in patients undergoing urgent operation or operation within three months of myocardial infarction, when non-aneurysmal ventricular function is poor, may be too high; it should be undertaken only under unusual circumstances.


A conductive catheter to improve patient safety during cardiac catheterization.

A 60 Hz current, as small as 20 microamperemeter (rms) is capable of causing ventricular fibrillation when directly applied to the heart. Significant cost and engineering effort has been spent to construct monitoring equipment which satisfies the safety regulations requiring maximum leakage currents below this value. Patients undergoing cardiac catheterization are particularly at risk from electrical hazards, primarily because catheters are made from nonconductive materials. A conductive catheter should allow externally applied currents to leak through its walls before reaching the catheter tip. A new electrically conductive catheter was compared with a standard nonconductive catheter. Five dogs were studied, with 81 attempts to cause fibrillation. Sixty-hertz voltage between the catheter and an external electrode was increased until fibrillation occurred or 130 V was reached. Eight states were studied in randomized sequence: conductive or nonconductive catheter, guidewire or saline-filled and tip touching wall, or free in left ventricle (verified by fluoroscopy and cineangiography). The saline-filled and conductive catheter was safer in that fibrillation never occurred, while fibrillation nearly always occurred with the nonconductive catheter. A conductive guidewire negates the protection of the conductive catheter. The application of conductive catheters could reduce instrumentation costs in laboratories and intensive care units and improve patient safety.


Relationship between plasma concentration and dose of digoxin in patients with and without renal impairment.

The purpose of this study was to determine if there is a linear relationship between oral doses of digoxin and various measurements of steady-state digoxin plasma concentration and urinary excretion in patients with wide range of renal function. Ten patients (mean age 58 years) with creatinine clearances greater than 50 ml/min/1.73 m2 BSA (mean creatinine clearance 80 ml/min/1.73 m2 BSA) and nine patients mean age 61 years) with creatinine clearances less than 50 ml/min/1.73 m2 BSA (mean creatinine clearance 20 ml/min/1.73 m2 BSA) were given digoxin tablets orally at two or three different dose levels (dose range 0.0313--0.5 mg/day). After a dosing period equal to at least five half-lives, three to four consecutive daily digoxin plasma concentrations were determined. Plasma concentrations and urinary digoxin excretion were measured during one 24-hour dosing interval at each dose level. Digoxin plasma and urine concentrations were determined in triplicate using radioimmunoassay. Individual patient plots provided evidence of linearity for: digoxin 24-hour steady-state plasma concentration vs dose; digoxin 24-hour cumulative urinary excretion versus dose; and area under the digoxin plasma concentration-time curve during a 24-hour dosing interval vs dose. Absolute values for these various parameters indicated substantial interpatient variation probably due to patient differences in both digoxin absorption and digoxin total body clearance. These results indicate that there is a linear relationship between digoxin plasma concentration and dose in patients with normal and decreased renal function. This linearity is support for dose-independent pharmacokinetics of digoxin in man. We conclude from these data that a change in digoxin dose should result in a proportional change in digoxin plasma concentration over the dose range examined.


Cardiac sarcoid: a clinicopathologic study of 84 unselected patients with systemic sarcoidosis.

Although sarcoid may involve the myocardium, there is little information on its incidence or significance. We studied 84 consecutive autopsied patients with sarcoidosis. The patients ranged in age from 18--80 years (average 46 years) and 61% were women; 23 (27%) of them had myocardial granulomas. In eight (35%) these were clinically silent, and in 15 (65%) there was a history of heart failure and/or arrhythmias and conduction defects. Of the 23 patients, only four (17%) had grossly evident, widespread myocardial lesions: three of these four (75%) had documented arrhythmias. All four had sudden, unexpected death at an average age of 36 years; in only two had sarcoid been suspected during life. The other 19 patients (83%) had microscopically evident granulomatous involvement. Of these, eight (42%) had a thythm or conduction disturbance and three (16%) sudden death, although none of those who suffered sudden death had a recognized rhythm or conduction disturbance. Nine (15%) of those without cardiac sarcoidosis had a rhythm or conduction disturbance and eight (13%) suffered a sudden death. The results show that although myocardial involvement occurs in at least 25% of patients with sarcoid, it most often involves a small portion of myocardium and is clinically silent. Since some of the 61 patients in whom myocardial lesions were not identified may still have had small microscopic granulomas, the true incidence of myocardial sarcoid may be even greater than suggested here. Rhythm and conduction disturbances are more common in the cardiac sarcoid group, but the findings suggest that only the small subset of patients with severe, grossly evident myocardial sarcoid are at increased risk for sudden death.


Electrode-catheter arrhythmia induction in the selection and assessment of antiarrhythmic drug therapy for recurrent ventricular tachycardia.

We performed intracardiac electrophysiologic studies in 33 patients with recurrent ventricular tachycardia. Nineteen patients underwent one, 10 patients two, and four patients three serial electrophysiologic studies. Ventricular tachycardia was successfully induced in 83% of the patients, and pacing methods were successful in terminating tachycardia in 71% of the studies, although pacing-induced acceleration of ventricular tachycardia occurred at least once in 36% of the studies. Seventeen of the 33 patients (52%) required a total of 24 external direct current cardioversions during study. In 21 patients a variety of antiarrhythmic drugs were given I.V. and attempts at ventricular tachycardia induction were repeated to assess prophylactic effects of the drugs. An acutely effective drug or combination of drugs was found in 15 of the patients (71%). Fourteen of the 15 were placed on chronic oral therapy with the effective agent and were followed for an average period of 8.1 months (range one to 33 months). In all 14 patients we could document complete (13 patients) or partial (one patient) long-term prophylaxis against ventricular tachycardia. We conclude that drug efficacy trials in patients with recurrent ventricular tachycardia using intracardiac pacing techniques is a rapid and accurate method of selecting effective long-term antiarrhythmic therapy.


Recurrent sustained ventricular tachycardia 3. Role of the electrophysiologic study in selection of antiarrhythmic regimens.

Twenty patients with recurrent sustained ventricular tachycardia (VT) underwent serial electrophysiological studies (EPS) 1) to determine the predictive value of the EPS in the selection of antiarrhythmic therapy, and 2) to establish the therapeutic efficacy of available antiarrhythmic agents. In each patient VT could be reproducibly initiated by programmed stimulation. After control EPS, the effects of several drugs (lidocaine, procainamide, quinidine, disopyramide and diphenylhydantoin) on the ability to initiate VT were assessed. An oral regimen was chosen on the basis of acute EPS and its effectiveness was evaluated by repeat EPS in 24--72 hours. Blood levels achieved acutely were used as guidelines to chronic therapy. In 14 patients the initiation of VT was prevented by the acute administration of one or more agents. In 13 of these patients, a chronic oral regimen based on these results prevented recurrence of VT with a three- to 27-month follow-up. In the remaining patient, oral therapy could not achieve blood levels of procainamide shown to be effective intravenously, and VT recurred. In six patients no single drug or drug combination was effective during acute EPS, and VT recurred in all while on therapy with the agent shown to make initiation of VT most difficult. Procainamide prevented VT in nine patients; quinidine in three patients; lidocaine in three patients; diphenylhydantoin in two patients; and disopyramide in one patient. The mean duration of EPS studies was 4.5 days. This study suggests that serial EPS provides rapid identification of successful antiarrhythmic therapy and can predict in which patients conventional therapy would be ineffective, thereby identifying patients requiring more aggressive modes of therapy.


Cellular immunity to a lung homogenate in asymptomatic cigarette smokers.

Leucocyte migration in the presence and absence of a soluble lung homogenate has been studied in a group of asymptomatic cigarette smokers. Results were expressed as migration indices. Controls consisted of age-matched subjects who had never smoked and had no past history of any pulmonary disease. The migration indices, the number of pack-years smoked and the results of pulmonary function studies were tested for correlation. The mean leucocyte migration index of the test group of sixteen smokers was significantly less than was that of the control group (P less than 0.001). Inhibition of leucocyte migration in the presence of the lung homogenate was not observed in any of the control subjects. Six of the sixteen asymptomatic cigarette smokers, however, were identified by inhibition of leucocyte migration in the presence of the lung homogenate. The number of pack-years which had been smoked did not correlate with the migration indices (r = -0.06); however, inhibition of leucocyte migration was not observed in subjects who had smoked less than 6 pack-years.


Effect of reagins and allergen extracts on radioallergosorbent assays for mite allergen.

The reproducibility of the radioallergosorbent (RAST) inhibition and direct binding assys with mite allergen were investigated in the presence of heterogeneous extracts and non-mite-sensitive atopic sera. Both contain components similar to potential contaminants which would occur in the assay of mite allergen and dust allergen and dust allergen extracts. The standardized inhibition and direct binding assays employed had a day to day (n = 4) coefficient of variation [(s.d. x 100)/mean] of 15% and 24% respectively. The inhibition assay for mite allergen was reproducible in the presence of protein concentrations of added plant, fungal, arthropod and animal extracts in excess of the protein concentrations that occur under the operational mite assay conditions. The mite inhibition assay was also reproducible in the presence of non-mite allergen extracts, with and without additional sera containing IgE specific for the non-mite allergens. The binding of a additional sera containing IgE specific for the non-mite allergens. The binding of a constant quantity of mite allergen to the activated solid phase in the direct binding assay was reproducible in the presence of added bovine serum albumin, and of a fungal or arthropod extract, representing the heterogeneous components of an allergen extract at the concentrations of total protein known to occur in the direct binding assay of mite extracts.


Allergy to penicillin unsuccessfully treated with a haptenic inhibitor (benzyl-penicilloyl-N2-formil-lysine; BPO-flys). A case report.

In a patient with a past history of allergy to penicillin and requiring treatment, skin tests with penicillin and penicilloyl-polylysine (PPL) were positive, and a penicilloyl RAST was strongly positive, although the Prausnitz-Küstner test to penicillin and PPL were negative. The haptin BPO-Flys was administered together with penicillin to try to prevent reactions. An anaphylactic reaction occurred on the fifth day, and treatment was stopped. Serum total IgE values increased markedly after the reaction and PK titres to penicillin and PPL reached values of 1/256. The skin test reaction to PPL was negative the day after the clinical reaction, but became strongly positive again a few days later. The penicilloyl RAST remained strongly positive throughout. The authors consider that there was hypersensitivity to a penicillin metabolite other than the penicilloyl group, e.g. to minor determinants, and for this reason the hapten inhibitor failed.


The seasonal symptoms of hyposensitized and untreated hay fever patients in relation to birch pollen counts: correlations with nasal sensitivity, prick tests and RAST.

A 2 year prospective study of thirty-eight birch pollen-sensitive hay fever patients under specific immunotherapy and of nineteen untreated control patients showed a significant correlation between the total seasonal symptom scores of the patients and their clinical sensitivities assessed by the RAST and a graded nasal test. The agreement between a positive nasal test and a positive RAST was 74%. In the early season with low pollen counts the onset of symptoms was significantly associated with high sensitivity of the patients, while many patients showed symptoms in the late season irrespective of their nasal and RAST sensitivity. About 90% of both the treated and the untreated patients reported mild symptoms when the pollen count exceeded 80/m(3) in the early season. 80% of them still had symptoms when the count was below 30/m(3) in the late pollen season. Although hyposensitization therapy had no effect on the occurrence of the mild symptoms, the treated patinets had severe symptoms significantly less often than the untreated ones on days with high pollen counts.


Relationship between nasal and conjunctival tests in patients with allergic rhinitis.

Simultaneous conjunctival and nasal provcation tests, a total of 174 test pairs, were carried out in fifty patients with allergic rhinitis, using serially diluted antigen solutions of birch, Timothy grass and mugwort pollen, as well as cat and dog dander. The nasal mucosa was found to be more sensitive than the conjunctival mucosa in ninety-six test pairs (55%). This differs from earlier reports. Nasal reaction only was observed in twenty-nine instances (17%). Posterior rhinomanometry was also used to evaluate test reactions, but was found to yield little additional information. In 43% of nasal provocation tests, which according to other criteria were positive, the rhinomanometric results were negative. Despite a fairly good correlation between the results obtained by nasal and conjunctival challenge, the results point to organ specificity in type I reactions. Provocation tests, if indicated in a thorough allergy evaluation, should be performed in the shock organ. The provocation methods and interpretation of reactions of this study differ from those of earlier reports. Comparison of results is difficult and standardization of methods is needed.


In vivo tests with pollen extracts previously investigated by means of direct RAST titration allergen assay.

The allergenic potency of different birch, Timothy and mugwort pollen extracts was determined by means of a direct RAST titration allergen assay. For birch and Timothy allergens, the results of skin and provocation tests did not confirm the results of the in vitro determinations of allergenicity. There was a poor correlation between the results of skin tests and the results of Phadebas RAST for determination of specific IgE to mugwort, whereas the correlation between skin tests and RAST for other allergens was excellent. It is concluded that direct RAST titration allergen assay is not adequate for all kinds of allergen preparations and that the Phadebas RAST for mugwort is less sensitive than the RAST for other allergens. The diagnostic efficacy of the different allergen preparations could not be evaluated.


Analysis of cell-mediated hypersensitivity, immune complexes and monocyte-released factor(s) in allergic alveolitis and asymptomatic exposed subjects.

Patients with allergic alveolitis to various antigens, asymptomatic exposed individuals and healthy control subjects were studied. The lymphocyte transformation test and the formation of two lymphokines were shown to be positive in almost all affected subjects and only rarely in asymptomatic exposed individuals. In most symptomatic subjects and only rarely in asymptomatic exposed individuals. In most symptomatic subjects, the presence of antigen-antibody complexes could be demonstrated. However, such complexes were also present in six of the nine asymptomatic exposed individuals having precipitating antibodies. Factor(s) released from sensitized monocytes strongly facilitate the in vitro formation of specific antibodies but are poorly effective when incubated with cells from asymptomatic exposed subjects or normal individuals.


Cell-mediated immune reactions in asthma.

Abnormally high levels of IgE are produced in various diseases, including atopic eczema, and a functional decrease in the T-lymphocyte population occurs at the same time. T-cell function has been studied in a group of asthma patients with high, normal and low IgE levels and in a control group. T-cell function appears to be reduced in asthmatic patients with high concentrations of IgE when skin tests are performed with Candida antigen (P less than 0.05). There was also a decline in the lymphocyte transformation tests with candida antigen in autologous serum (P less than 0.05), although not in foetal calf serum. The responses to in vivo tests with streptokinase-streptodornase were normal, as was the response of the lymphocytes to PHA.


The use of the radioallergosorbent test in the diagnosis of Hymenoptera anaphylaxis.

IgE antibody levels to Hymenoptera (honey bee, hornet, wasp or yellow jacket) venom or venom sac were measured in the serum of ninety-six patients with a history of immediate hypersensitivity reactions to these insect stings. Normal levels of IgE antibody were found in fourty-four of these patients tested. The severity of the systemic reaction was similar in those patients with normal and elevated IgE antibody levels, and the interval from the systemic reaction to antibody determination was also similar. In twelve patients with a definite reaction to honey bee venom, the IgE antibody was elevated in all and correlated with a positive venom skin test in nine out of the twelve. It is not possible to determine if the other patients with normal IgE antibody and a systemic reaction represent a false negative RAST value, loss of sensitivity to the Hymenoptera venom, or a lack of RAST sensitivity with some venom or venom sac antigens. Without the ready availability of venom skin tests to all Hymenoptera antigens or other in vitro tests, a definite assessment of insect anaphylaxis remains in doubt for the patient and physician.


A clinical comparison of aerosol and powder administration of beclomethasone dipropionate in asthma.

A clinical comparison of conventional aerosol administration of beclomethasone dipropionate and insufflation as a powder using the "Rotahaler" device in four doses of 100 microgram each was made in thirty-seven cases. Each treatment was given for 4 weeks, the order being randomized. Symptom records, twice daily peak flow readings and records of bronchodilator and steroid dosage showed the powder to be as effective as the aerosol. In the physician's opinion the powder was preferable to the aerosol in some cases.


Complement changes during exercise-induced asthma.

Two groups of asthmatic children, one with and one without a history of post-exercise wheezing, and one non-asthmatic adult, were exercised on a treadmill, and their complement levels were measured before and after exercise. The first group of patients had the most obvious fall in FEV 1 and all showed a slight rise in haemolytic complement following exercise. Two of the patients of the second group also had a rise in haemolytic complement. The C4 titre did not change in any of the asthmatic children who did not wheeze after exercise, but there were changes, albeit inconsistent, in the titres of C4 in four of the six patients who exhibited post-exercise wheezing. C3 breakdown products were not detected in any of the sera, following exercise. The role of complement in exercise-induced bronchospasm is not clear, but there does appear to be a greater lability of the complement system in patients who are susceptible to this form of provocation.


Lymphocyte transformation in extrinsic bronchial asthma.

Lymphocytes from sixteen patients with extrinsic bronchial asthma and sixteen normals were investigated for their in vitro reactivity to stimulation with phytohaemagglutinin (PHA) and concanavalin A (Con A). No significant differences in maximum lymphocyte responses to PHA or Con A, either in the presence of foetal calf serum or autologous plasma, were found. The significance of these results in relation to T suppressor cell control of IgE formation is discussed.


Humidifier fever and endotoxin exposure.

Three cases of humidifier fever were detected in an office environment. Flavobacteria were found in the contaminated water in a humidifier. After an experimental exposure, the three persons with previous symptoms suffered from fever and slight respiratory symptoms. A leucocytosis and an increase in the number of segmented white blood cells were found the day following the exposure. General immunoglobulins as well as antibodies to Flavobacterium and endotoxin were slightly elevated in the exposed group. The possibility that endotoxins may be the causative agent by means of an indirect complement activation is discussed.


Measurement of nasal patency using a Vitalograph.

A standard Vitalograph was used to measure the volume of air inspired through the mouth (M-FIV0.5) and nose (N-FIV0.5) in 0.5 sec. The ratio of these parameters was used as a nasal patency index (NPI) and the characteristics of NPI and N-FIV0.5 investigated in terms of reproducibility and sensitivity. Both indices were significantly reduced by intranasal histamine (100 micrograms and 200 micrograms) and it is concluded that NPI and N-FIV0.5 are reproducible and sensitive indices of nasal patency.


Asthma and extrinsic allergic alveolitis due to Merulius lacrymans.

A teacher with breathlessness of insidious onset developed acute symptoms on return home following his discharge from hospital. His flat was found to have extensive dry rot (Merulius lacrymans). Precipitins and specific IgE and IgG antibody against M. lacrymans were present and intracutaneous testing gave a typical dual skin reaction. Pulmonary physiology demonstrated airflow obstruction with a low DLCO and KCO, and a chest X-ray showed diffuse micronodular shadowing, maximal in the mid-zones. Inhalation challenge testing provoked a combined asthmatic reaction without a change in DLCO. Rapid clinical recovery and more gradual radiographic and physiological improvement followed cessation of exposure to the antigen.


Methods of quantifying circulating IgE.

Four radioimmunoassay techniques, two conventional and two sandwich, have been used to measure circulating IgE levels in 100 sera. The test sera had IgE levels ranging from 1.0 to 20,000 u/ml, and each was measured at five dilutions, ranging from three-fold to 400-fold. The same IgE standards were used throughout, and the optimal range for each assay was determined by assessing data for quality control sera and the WHO standard 69/204. To be of general use in the United Kingdom an IgE test must measure accurately levels as low as 20-30 u IgE/ml. The Phadebas RIST method failed to meet this criterion, and of the remaining tests the double antibody method had the most useful operating range and produced the most reliable results. However, the double antibody method is not available commercially and so, for the majority of laboratories, the Phadebas PRIST technique should be the method chosen.


Serum IgE levels in amoebiasis.

Elevated levels of serum immunoglobulin E (IgE) are found in many parasitic diseases. In order to determine the influence of Entamoeba histolytica on IgE levels of clinically symptomatic patients with intestinal amoebiasis, a controlled study was performed. There was no difference between the serum IgE values from Brazilian patients with amoebiasis and those from age-, race- and sex-matched normal Brazilian controls. Based also on our previous similar studies on giardiasis and Chagas' disease, we conclude that protozoan infections do not elevate serum IgE levels.


Occupational asthma in Finland.

In Finland occupational asthma caused by protein allergens and reactive chemicals present in the air of work environments is increasing. This communication describes provocative challenge tests and methods for measuring exposure under simulated work conditions. The importance of lung function measurements during non-exposure and placebo periods is stressed. Especially late reactions are difficult to assess because of the great circadian variation in the lung function parameters of asthmatics. For a positive challenge test, a decrease in peak flow values of at least 15% and a clear deviation from normal circadian variation and placebo periods is required. The allergens of vegetable or animal origin primarily affect patients with an atopic constitution. Chemical allergens seem to attack all exposed workers in the same way. The report lists the occupations with risk for asthma and refers to the population at risk; bakers seem to be the group with the most risk. The importance of early diagnosis, removal of the worker from exposure and improvement of the hygienic aspects of the work environment are stressed.


Aerobiological studies based in Derby. I. A simplified automatic volumetric spore trap.

A simplified version of the Hirst automatic volumetric spore trap has been developed in Derby for aerobiological studies. In comparative trials, the number of spores retained by the Morrow Brown trap were similar in the case of larger spores such as Alternaria (102%), rather higher in the case of grass pollen (136%) and considerably higher (166--201%) for very small spores such as Sporobolomyces and Tilletiopsis. Impaction efficiency has been improved by using a narrower slit. The trap designed in Derby is simple to produce and presents advantages in design over the Hirst version.


Aerobiological studies based in Derby. III. A comparison of simultaneous pollen and spore counts from the east coast, Midlands and west coast of England and Wales.

The air spora of two sites on the east coast of Britain and one on the west coast were compared with each other and with the regular sampling site in Derby by the simultaneous operation of volumetric spore traps. Concentrations of airborne spores and pollen were found to be usually less at the coastal sites than in Derby. The effect of wind direction was shown to be important at coastal sites because daily counts often showed rises and falls corresponding to off- and on-shore winds respectively. Counts at the west coast site were nearly always lower than those on the east. These findings, together with the prevalence of westerly winds over Britain and the different land use in the east and west, suggest that fewer airborne allergens may be encountered on the west coast.


Serum ribonuclease of normal persons and patients with renal impairment.

Serum ribonuclease of normal persons and of patients with renal impairment was determined with polycytidylic acid as substrate. There was a pronounced rise in the serum ribonuclease of patients with renal impairment. Average serum ribonuclease values of 25 normal persons and 25 patients with renal impairment, respectively were 110 and 2329 units per ml of serum. Serum ribonuclease, because of its unique specificity, stability and abnormal elevation in the sera of patients with renal failure, might serve as an additional indicator in the assessment of renal function.


Semi-automatic data processing in clinical chemistry.

A semi-automatic system for data processing in the Clinical Chemistry Department of the School of Pathology, Johannesburg, is outlined. Careful planning of workflow in the laboratory can provide a better interface of laboratory results with a manual cumulative reporting system in which technologists and clerks co-ordinate their activities. The system used provides a less tedious and less error-prone process via automatic printing facilities. This system achieves improved patient care in terms of quality control (data checks) and cumulative reporting of results. Facility for accounts and administration purpose are also incorporated. In our experience, semi-automatic data processing can provide a solution to the clerical problems generated by the introduction of automatic testing equipment. Hardware costs are minimal in comparison to fully automated systems, which utilize on-line or off-line computers.


Reliable fifteen-minute assay for theophylline.

We describe a reliable, rapid high pressure liquid chromatography assay for serum theophylline which can be performed on 0.5 ml or smaller samples. The procedure involves extraction, centrifugation and sampling all in the same disposable centrifuge tube. In the therapeutic range the coefficients of variation for within-day and day-to-day assays are 1.0% and 2.6%, respectively. The sensitivity of the method is better than 1 microgram/ml in serum. The minimum number of steps, rapid elution and use of only peak heights contribute to the reliability and rapidity of the assay.


The effects of acute and chronic uremia in rats on their hepatic microsomal enzyme activity.

The activity of the hepatic microsomal enzymes hexabarbital oxidase, aminopyrine demethylase, and p-nitrobenzoic acid reductase were determined in the chronically uremic rats, acutely uremic rats and controls. Plasma corticoid levels (corticosterone) were also measured in all groups. A significant reduction in the hepatic microsomal enzyme activity as compared to controls was observed in both groups, with the chronic group showing slightly greater reduction. Furthermore, while plasma corticoid levels were significantly elevated in both groups, the acute uremic group had plasma corticoid levels which were almost twice the levels found in the chronically uremic animals. The significance of these observations are discussed.


A sensitive method for the determination of hydrochlorothiazide in serum by high pressure liquid chromatography.

A high pressure liquid chromatographic method for the determination of hydrochlorothiazide in serum has been elaborated and verified in a blood level study in normal individuals given a single oral dose of 50 mg hydrochlorothiazide. Based on 5 ml of serum, the limit of detection of the method is 2 ng/ml.


Comparison of CK-MB fractionation by antibody inhibition reaction and DEAE-sephadex chromatography.

1. CK-MB isoenzyme fractionation has been compared between DEAE-sephadex chromatography and the CK-M-subunit inhibiting antibody procedure. 2. It was found that the inhibiting antibody method generally gave lower values than the chromatography procedure. 3. The above difference can be partially attributed to inhibitory factors in the antibody system. 4. It was concluded that although there was general agreement between the two procedures, the CK-M-subunit inhibiting antibody procedure should be viewed with caution at low creatine kinase activities, and should never be done without the appropriate reagent blanks.


A study of factors affecting laboratory workload.

1. The use of a mathematical modelling technique is described. The factors influencing the day to day variation in laboratory workload were investigated to provide for accurate management forecasts. Analysis by linear stepwise regression showed that a potentially controllable factor the clinician ordering habits, accounted more significantly in this variation than less controllable factors such as admissions, routine and acute, total occupied beds and public holidays. 2. The significant factors remained valid after a review period of one year.


A water purification system for laboratory use.

A water purification system is described, capable of producing Type I water upon demand at multiple locations up to 700 feet, from the purifying equipment. Tap water is initially treated employing reverse osmosis, followed by treatment with activated charcoal and mixed anion/cation exchange resins. The resultant Type I quality water is maintained by means of a recycling loop until removal upon demand. The current cost of producing water of this quality is $0.03 per liter, exclusive of capital and installation costs.


Experience with Boehringer Mannheim GOD/PAP (Trinder) glucose reagent kit on Autoanalyser I and SMA 12/60 systems.

We report here our experience with Boehringer Mannheim GOD/PAP (Trinder) glucose kit on Autonanalyzer I and SMA 12/60 systems. With slight modification on the existing procedures, we are able to obtain an efficient method that yields satisfactory results with very low cost.


Estimation of free triiodothyronine in serum: a new method and its clinical relevance.

We describe a method for estimating free triiodothyronine in serum by polyacrylamide gel filtration. Precise and easy to perform, it avoids the lengthy incubation required for equilibrium dialysis. Results of this procedure correlate well with those by the dialysis method over a wide range of thyroid states. The role of free triiodothyronine as part of a protocol for the evaluation of thyroid status is discussed.


Additive, multiplicative, and mixed analytical errors.

Depending on the change in magnitude of analytical error occuring with change in concentration of analyte, two limiting types of error properties can be defined: additive and multiplicative. We investigated whether one of these two error types also characterizes the overall error of methods involving multiple procedural steps, or whether mixed error properties result in these cases. Using "open" quality-control data (i.e., and analyst identifies controls) from each of two hospitals and "blind" quality-control data from one hospital for 11 different assays, we found: (a) With current methodology, overall errors typically are mixed, though predominantly additive and multiplicative overall errors exist as well. (b) "Blinding" the quality-control system typically augments the multiplicative but not the additive error component.


Mass-fragmentographic determination of catecholamine metabolites in amniotic fluid and its possible clinical usefulness.

We describe the determination of 3-methoxy-4-hydroxy-phenylacetic acid, 3-methoxy-4-hydroxyphenylamandelic acid, and 3-methoxy-4-hydroxyphenylethylene glycol in amniotic fluid by means of mass fragmentography, with use of deuterated internal standards. The results expressed in terms of absolute concentration and creatinine concentration, are given as a function of gestational age. In the 15th to 17th week, concentrations in amniotic fluid are a reflection of those in the mother's serum, whereas in the 32nd to 40th week, these concentrations, expressed in terms of creatinine, are similar to those found in the urine of newborns. We discuss the possible usefulness of the determination of catecholamine metabolites in amniotic fluid in the diagnosis of congenital neuroblastoma, maternal pheochromocytoma, and underdevelopment.


New enzymatic method for serum uric acid at 500 nm.

We describe a manual method, well suited to mechanization, for quantitating serum uric acid at 500 nm. In the assay mixture (0.10 ml of sample and 3.00 ml of reagent) the hydrogen peroxide produced from uric acid by uricase is coupled with p-hydroxybenzoate and 4-aminoantipyrine in the presence of peroxidase to form a colored complex, which is measured. A separate sample blank is obviated by taking an initial absorbance measurement 20 s after the sample is added. The reaction is complete within 5 min; its sensitivity is 0.001 deltaA/mg per liter. Absorbances are linearly related to uric acid concentrations up to 120 mg/liter. Many substances that may be present in normal serum do not interfere, but bilirubin in moderately above-normal concentrations will interfere. The procedure can be modified to largely correct for this, when necessary. The proposed method (y) correlated well (r = 0.979) with the uric acid 293 nm reference method (x) and the relation is described by the equation y = 0.998x + 2.42.


Bisalbuminemia. A new molecular variant, albumin Vancouver.

Of 18 members of a Fiji Indian family investigated, eight of the 12 males and two of the six females had an electrophoretically slow-type bisalbuminemia (alloalbuminemia). The albumin was characterized by the hiterto unique ratio of the two bands (Al A 35%: variant 65%), and by dye-binding studies and electrophoretic mobility in different media. The data suggest that this is a new variant, which we propose to call albumin Vancouver (Al Va).


Serum prostate-specific acid phosphatase: development and validation of a specific radioimmunoassay.

We describe radioimmunoassay for human prostatic acid phosphatase [orthophosphoric-monoester phospho-hydrolase (acid optimum), EC 3.1.3.2] in serum, with use of monospecific antisera raised in rabbits against highly purified acid phosphatase from human prostates. The antiserum did not cross react with partly purified acid phosphatases from human spleen, erythrocytes, or synovial tissues. 125I-labeled acid phosphatase was prepared by a Chloramine T method, and the bound and free antigen was separated in the assay by use of anti-rabbit gamma-globulin raised in sheep. Uniform low nonspecific binding of the [125I]acid phosphatase was achieved by using acid-phosphatase-free serum to prepare standard curves and diluted samples of serum with high acid phosphatase activities. Concentrations of immunoreactive acid phosphatase in the serum of healthy men ranged from  less than 1 to 10 microgram/liter and for 12 patients with advanced prostatic carcinoma between 100 and 500 microgram/liter. The concentrations of the enzyme in sera of patients with benign prostatic hyperplasia were very similar to those in sera of the reference group.


Simultaneous determination of retinol and retinyl esters in serum or plasma by reversed-phase high-performance liquid chromatography.

We propose a single-run liquid-chromatographic determination, with ultraviolet detection at 330 nm, for serum retinol and retinyl esters. The vitamin A derivatives are extracted according to the Bligh-Dyer procedure. With 200 microliter or serum, the lower detection limit is 50 microgram/liter for retinol and about 100 microgram/liter for retinyl esters. Within-run precision (CV) was 2.3% for retinol, 4.3% for retinyl palmitate. Day-to-day percision (CV, n = 20) for retinol was 4.9% during a month. The method can be used for the assessment of vitamin A absorption tests and for the determination of serum retinol (normal, subnormal, and above-normal concentrations). Serum retinyl esters can only be measured in conditions where concentrations exceed 100 microgram/liter.


A water-soluble cholesterol derivative for use in augmenting serum control materials.

Cholesterol determination has been hampered by the lack of suitable means to prepare lyophilized serum control materials with an appropriate range of values. We prepared a water-soluble cholesterol derivative by first esterifying cholesterol with adipic acid and then reacting the cholesterol hemiadipate with Polyethylene Glycol 600 to form polyethoxyethanyl-cholesteryl adipate. The compound reacts quantitatively in several commonly used methods, including enzymic, extraction, and direct-assay procedures. When the additive is directly mixed with human serum that has been depleted of beta- and pre-beta-lipoproteins, an optically clear solution results for which cholesterol values are stable. The clarity is retained upon lyophilization and reconstitution. Addition of this cholesterol compound to partially delipidized serum appeared to have no significant effect on results of assay of 18 other commonly measured serum constituents.


Radioenzymatic assay of DOPA (3,4-dihydroxyphenylalanine).

We modified the single-isotope radioenzymatic assay for catecholamines [Life Sci. 21, 625 (1977)] to assay 3, 4-dihydroxyphenylalanine (DOPA). DOPA decarboxylase is used to convert DOPA to dopamine, which concurrently is converted to [3H]-3-O-methyldopamine in the presence of catechol-O-methyltransferase and [methyl-3H]-S-adenosylmethionine and assayed radioenzymatically. For assay of plasma DOPA, 50 microliter of untreated plasma is added directly into the incubation mixture. A duplicate mixture containing an internal standard requires a second 50-microliter aliquot of plasma. Because the assay measures both DOPA and endogenous dopamine, two additonal aliquots of plasma must be assayed for dopamine in the absence of the decarboxylase by the differential assay; DOPA is estimated by difference. The assay is sensitive to 25 pg (500 ng/liter of plasma). Analysis of DOPA (DOPA plus dopamine) and the concurrent differential assay of catecholamines in at least 10 samples can be done in a single working day. Plasma DOPA concentrations for 42 normotensive adults were 1430 +/- 19 ng/liter (mean +/- SEM). In contrast, do-pamine concentrations for these same subjects averaged 23 +/- 20 ng/liter. Values for the 24 women subjects (15 10 +/- 62 ng/liter) significantly (P = 0.04) exceeded those for the men (1320 +/- 75 ng/liter).


Standardization of the Coomassie Blue method for cerebrospinal fluid proteins.

Coomassie Brilliant Blue G-250 can be used to quantitatively determine proteins in cerebrospinal fluid. When the dye combines with protein, the absorption maximum of the dye shifts. The dye-protein color forms almost instantaneously and is stable for at least 1 h. The procedure is also insensitive to changes in temperature in the range of 20--30 degrees C. The absorptivities of the dye complexes with human albumin or globulin differ, thus a pure albumin or pure globulin standard is unsuitable; a standard containing 70% albumin and 30% globulins is the most appropriate for this application. A bichromatic approach to standardization increases the range of linearity of a calibration curve. The method gives values that are about 9% higher than a sodium sulfate-sulfosalicylic turbidimetric procedure for cerbrospinal fluid proteins.


Proteinuria: accuracy and precision of laboratory diagnosis by dip-stick analysis.

We studied and compared results of two urine dip-stick procedures for protein with those of quantitative measurements of total protein and albumin in urine. Sensitivity, specificity, and predictive value of "normal" and "abnormal" dip-stick results, assay efficiency, technologist precision, and method association were determined. Precision was poor, attributable largely to variation within each technologist. Relative to a defined measure of precision, technologist performance appears to be uniform within each product. Patients' urinary protein concentrations of less than 200 mg/liter can be distinguished from concentrations greater than 3000 mg/liter with confidence by dip-stick procedures. Urin samples with low albumin/total protein ratios were frequently falsely negative by dip-stick assays.


High-performance liquid-chromatographic assay of aminoglycoside antibiotics in serum.

We describe procedures for the high-performance liquid-chromatographic assay of gentamicin, amikacin, and tobramycin in serum. The aminoglycoside antibiotic is extracted from serum by using a CM-Sephadex column and is measured by reversed-phase, ion-pair chromatography. Continuous-flow, post-column derivatization with o-phthalaldehyde is used to form fluorescent products for detection. An internal standard is used in each assay. Synthesis of 1-N-acetylgentamicin C1, the internal standard for the gentamicin assay, is described. For each procedure, concentration and instrument response are linearly related in the range of therapeutically important concentrations. The methods are precise and results correlate well with results obtained by bioassay. The between-day CV (n = 10) for each procedure was less than 4%. No substances have been detected in clinical specimens that interfere with these chromatographic procedures. The possible use of these methods for analysis for other aminoglycoside antibiotics is discussed.


High-performance liquid-chromatographic simultaneous determination of commonly used tricyclic antidepressants.

We report a method for simultaneous measurement of five commonly used tricyclic antidepressant drugs (doxepin, desipramine, nortriptyline, imipramine, and amitriptyline) in serum by paired-ion high-performance liquid chromatography, with use of a reversed-phase column and ultraviolet detection at 254 nm. The drugs are extracted from 2 ml of serum at pH 14 into hexane/isoamyl alcohol (99/1 by vol) and re-extracted into 200 microliter of 0.1 mol/liter HCI. An aliquot of the aqueous acid phase is chromatographed with use of a methanol/acetonitrile/water (41/15/44) solvent system, containing 5 mmol of pentanesulfonic acid per liter of phosphate buffer (0.1 mol/liter, pH 6.5), at a flow rate of 1,5 ml/min. Analytical recoveries of the drugs from serum increase with increasing concentration, from 62% at 25 microgram/liter to 93% at 300 microgram/liter. Linear response is observed for drug concentrations up to 1500 microgram/liter and the detection limit is 2-3 microgram/liter. Within-run precision ranges from 1.4 to 2.9% and day-to-day precision from 1.7 to 7%, depending on the specific drug. The entire procedure can be completed within 45 min and is well adapted to the routine clinical laboratory. Of 48 common basic and several neutral drugs tested for possible interferences, only three benzodiazepines, three phenothiazines, and three antihistamines interfere with the assay of doxepin, desipramine, and nortriptyline, respectively.


A one-tube micromethod for radioimmunoassay of plasma cortisol.

A micro-scale method is presented for measurement of cortisol. Serum or plasma, 2 microliter, is diluted with buffer and the solution heated at 60 degrees C in the presence of high-affinity antibody and [3H] cortisol. Corticosteroid-binding globulin in the serum is denatured, releasing cortisol and making it available to the antibody, which is stable during the incubation. After cooling, ammonium sulfate solution is added, followed by a toluene-based scintillant that does not dissolve in the aqueous phase. The vial is shaken to extract the free cortisol into the scintillant. Antibody bound cortisol remains in the aqueous phase and does not produce any scintillation. The amount of [3H] cortisol that is free at the end of the incubation, and which therefore gives rise to the measured counts, is related to the concentration of cortisol in the original serum, and may be calculated from a standard curve. The assay is sensitive and precise. Ranges are presented for normal and pathologic subjects.


Modification of the choriogonadotropin beta-subunit radioimmunoassay for determination of urinary choriogonadotropin.

The choriogonadotropin beta-subunit radioimminoassay has been used extensively to measure human choriogonadotropin in the sera of pregnant women and individuals with trophoblastic and nontrophoblastic tumors. Unmodified, this method cannot be used to measure choriogonadotropin in urine because of interfering substances. We circumvented the non-parallelism between the standards and serial dilutions of urine containing choriogonadotropin by adding pooled urine from men to the standard tubes and limiting the volume of urine to 100 microliter. This modified assay has a sensitivity of 3 int. units/liter of urine and is specific for choriogonadotropin concentrations of 40 int. units/liter of urine. Analytical recovery of choriogonadotropin added to urine ranged from 96 to 105%. The within-assay CV was 7.6%; the between-assay CV was 11.8%. Concentrations of choriogonadotropin in concurrently collected serum and urine samples from pregnant women correlated well. The test can be performed within 24 h by using the double-antibody method for separating bound from free hormone, or in 3 h with a dioxane method. The assay is about 20-fold more sensitive than the 2-min or 2-h slide and tube pregnancy tests, and seven-to 12-fold more sensitive than the radioreceptor assay.


Serum ionized calcium and corrected total calcium in borderline hyperparathyroidism.

We studied 25 borderline-hyperparathyroidism patients whose total serum calcium concentration was within normal limits (reference range: 2.25--2.75 mmol/liter) but whose concentrations of serum ionized calcium were above normal (reference range: 1.03--1.23 mmol/liter). Their hyperparathyroidism was histopathologically verified. To compare the discriminating value of corrected serum calcium with ionized calcium, we studied the serum calcium and albumin concentrations in a reference group of 2098 patients. After patients from endocrine and dialysis departments were excluded from the reference group, we obtained the range (mean +/- 2 SD) 2.05--2.71 mmol/liter for uncorrected serum calcium and 2.11--2.63 mmol/liter for corrected serum calcium. The correction factor for calcium on albumin was 20 mumol/g. Even with this limit for corrected serum calcium, 13 of 25 borderline hyperparathyroidism patients had values that fell within the reference range. We conclude that correcting total serum calcium values for serum albumin concentration improves discrimination of borderline hyperparathyroid patients, but that measurement of ionized calcium in serum discriminates better.


Effect of in vitro hemolysis on chemical values for serum.

Hemolysis in serum specimens is commonplace. This study examines the effect of hemolysis on results of selected chemical assays. Hemolysis was simulated by adding hemolysate to serum to give hemoglobin concentrations of 90 to 2800 mg/liter and a rating by technologists of 0 to 4 + hemolyzed. The effect of hemolysis on values for some serum constituents, particularly acid phosphatase and creatine kinase, was shown to be method dependent. Not unexpectedly, hemolysis most affects results for lactate dehydrogenase.


Isoenzyme distribution of creatine kinase and lactate dehydrogenase in serum and skeletal muscle in Duchenne muscular dystrophy, collagen disease, and other muscular disorders.

We determined the total activity and isoenzyme distribution of lactate dehydrogenase and creatine kinase in serum and biopsy specimens from skeletal muscle of nine normal individuals and nine patients with Duchenne muscular dystrophy (I), five with collagen disease (II), and four with non-progressive unclassified myopathy (III). Mean total serum creatine kinase in patients with Duchenne muscular dystrophy (867 U/liter, SD = 197) was 31-fold that in the control group (28 U/liter, SD = 14). There was also a small (3.3-fold) increase in the mean total serum creatine kinase of patients with III, but none in the serum from patients with II. Changes in the creatine kinase isoenzyme distribution of skeletal muscle were primarily in the MB isoenzyme. The mean percentage of creatine kinase-MB activity in muscle from patients with I (2.81, SD = 1.15) and patients with III (1.69, SD = 1.07) significantly (P less than 0.005) exceeded that of the control group (0.43, SD = 0.18). Muscle from patients with II showed little change. The most striking changes in lactate dehydrogenase were also observed in patients with I, in whom the mean total serum activity (356 U/liter, SD = 115) was 3.4-fold that of serum from the control group (105 U/liter, SD = 19). Skeletal muscle from these patients also showed a significant decrease in mean percent isoenzyme 5 activity (from 50 to 23) and an increase in that of isoenzymes 1 and 2 (from 1 to 9 and 8 to 20, respectively). These changes in the distribution of these two sets of isoenzymes in muscle were reflected in the serum.


Serum galactose determination with centrifugal analyzers.

I describe a rapid quantitative centrifugal analysis for galactose in blood. The technique involves galactose dehydrogenase. As compared to the manual (o-toluidine) method for galactose determination, analysis time (4 min 45 s on the GEMSAEC, 4 min 10 s on the CentificCHEM) and sample volume  (5 microliter) were considerably reduced. Sample deproteinization is eliminated. A modified commercial kit was also tested. Results by the procedure correlate well with those by the more classical methods and analytical recovery is about 100%. The method is applied to the determination of galactose in intravenous galactose tolerance tests. Results of actual tests are reported.


Trace elements in scalp-hair of persons with multiple sclerosis and of normal individuals.

Scalp-hair samples from 40 multiple sclerosis patients and 42 controls were analyzed by neutron activation analysis, with a SLOWPOKE reactor as the neutron source. Ag, Al, As, Au, Ba, Br, Ca, Cl, Cu, l, K, Mg, Mn, Na, S, Sb, Se, Sr, V, and Zn were determined in samples of about 0.1 g. Highly significant differences (99% confidence) were observed between the two groups in concentrations of Cu, l, Mn, S, Se, and V.


Determination of 3-methoxy-4-hydroxyphenylpyruvic acid, 3,4-dihydroxyphenylethylene glycol, and 3,4-dihydroxyphenylmandelic acid in urine by mass fragmentography, with use of deuterium-labeled internal standards.

We report the determination of 3-methoxy-4-hydroxyphenylpyruvic acid, 3,4-dihydroxyphenylmandelic acid, and 3,4-dihydroxyphenylethylene glycol in urine, by use of gas chromatography/mass spectrometry in combination with a simple purification method and deuterium-labeled internal standards. Normal excretion values in terms of creatinine, expressed as a function of age, are given, together with results obtained for patients with neuroblastoma, pheochromocytoma, or parkinsonism treated with L-DOPA + peripheral decarboxylase inhibitor, and for a patient receiving dopamine. We were unable to identify 3, 4-dihydroxyphenyllactic acid in urine. The results obtained and their relation to other catecholamine metabolites and catecholamine-precursor metabolites in urine are discussed.


Copper coproporphyrin excretion in familial coproporphyria.

Analysis of stool specimens from a patient with familial coproporphyria by high-performance liquid chromatography revealed that 112 microgram per gram of dry feces (14% of the total porphyrin present) was copper coproporphyrin. Examination of stool specimens from other patients with this disease confirmed the presence of significant amounts of both copper coproporphyrin and coproporphyrin. Further investigation showed that the copper coproporphyrin was probably formed by a nonenzymic incorporation of copper by the coproporphyrin in either the bile or feces.


Relative merits of two electrophoretic and two column-chromatographic kets for determining serum creatine kinase isoenzyme MB activity.

Prospective analysis (by use of commercially available kits) of 339 validated admission specimens from patients consecutively admitted to a cardiac monitoring unit revealed sensitivities of 68 and 63% for two electrophoretic assays (Bioware and Helena) and up to 73 and 77% for two chromatographic assays (Roche and Worthington). Specificities were 94.8, 96,6, 90.2, and 89.7% and efficiencies were 90.2, 90.7, 87.0, and 87.0, respectively. Although these results differ from early reports, they agree well with several recent studies. However, 86 (25%) of the specimens gave at least one discrepant result based on clinical evaluation of the patients, and 68 (20%) gave at least one discrepant result between methods.


Continuous-flow enzymic method evaluated for measurement of serum triglycerides with use of an improved lipase reagent.

We compared a modified enzymic continuous-flow method for serum triglycerides, in which a microbial lipase is used without protease, to an extraction-fluorometric method. Results (for total--blank) correlated well with those by the comparison procedure: enzymic = 1.002 fluorometric--14 mg/liter; r = 0.9968. Serum blanks were measured for each sample in both methods, and the concentration of free glycerol measured by the enzymic method was shown to be as much as 15 to 71% of the total triglyceride result in 7% of the samples analyzed. The dual-channel continuous-flow system provides automatic free-glycerol blank subtraction for the enzymic method.


Measurement of plasma nortriptyline concentrations: radioimmunoassay and gas-chromatography compared.

We compared measurement of plasma nortriptyline by a recently developed radioimmunoassay technique with values obtained by traditional gas chromatography. The coefficient of correlation (r) was 0.98 for 84 samples from 21 controlled patients; for a separate series of 45 samples from 34 patients who were receiving in addition other medication, r was 0.96. Use of radioimmunoassay in the routine determination of plasma nortriptyline concentration is discussed.


Manual and centrifugal analyzer determination of cholesterol and triglycerides with single-vial enzymatic reagents.

We have assessed Calbiochem single-vial enzymatic reagent systems for the analysis for cholesterol and triglycerides, using manual and centrifugal analyzer techniques. Analysis for cholesterol by both techniques had acceptable performance by the short-term criteria of the Center for Disease Control (CDC) during this study carried out under optimal conditions of variance. Analysis for triglycerides by the manual technique did not meet CDC criteria, and we do not recommend use of this method. Analysis for triglycerides by the centrifugal analyzer technique had acceptable short-term precision but had unacceptable accuracy at high concentrations of triglycerides; this method may be considered to have acceptable performance for routine laboratory use.


Mechanized micro-scale determination of protein in platelet pellet sonicates.

With the method described here, samples can be assayed at the rate of 40/h, with increased reproducibility. As described, the method covers an analytical range of 1 to 7 g/liter, but it can be readily adapted to measure different ranges of concentration in other protein preparations.


Immobilized-enzyme membrane sandwich reactor used in automated micro-scale assay of plasma uric acid.

We describe the automated microassay of plasma uric acid by use of an immobilized uricase-membrane sandwich reactor. Hydrogen peroxide, formed when uric acid is oxidized, oxidatively couples two molecules of p-hydroxyphenylacetic acid in the presence of peroxidase to produce a highly fluorescent compound. The specificity of the uricase reaction is coupled with a significantly lower cost of analysis.


Continuous-flow analysis for serum albumin, by use of the immediate reaction with bromcresol green.

Albumin reacts with bromcresol green reagent almost immediately, other serum proteins more slowly. This phenomenon can be exploited to improve the specificity of this routine method for determining serum albumin. I describe a 30-s reaction as adapted to continuous-flow analyzers, with no interference from other serum proteins. The method shows linearity to 72 g/liter. Results of this method correlate very well with those by the Laurell "rocket" and manual (30-s) bromcresol green methods. This procedure gives a considerable improvement in specificity for continuous-flow analyzers as compared with current bromcresol green methods.


Should blood samples for assay of plasma renin activity be chilled?

Collecting blood on ice for renin determination reportedly may produce falsely high results. To assess the probability of this occurring under actual collection conditions, we measured renin activity in duplicate aliquots of plasma from blood samples from 25 hypertensive patients, both supine and upright, and in 10 supine normotensive controls. One aliquot of the blood was collected on ice and processed at 4 degrees C, the other at room temperature. The two aliquots showed no significant differences in renin activity. If anything, values for samples collected at room temperature were higher. Repeat determination on the same specimens stored at--20 degrees C for nine and 12 months revealed no significant changes in results for any samples, although the amount of angiotensin I found in the sample before incubation at 37 degrees C significantly increased. We conclude that it makes little difference at what temperature one collects blood for renin determination, but because of the wide fluctuations in "room" temperature we recommend that blood samples be collected on ice.


Enzymatic determination of plasma ammonia: evaluation of Sigma and BMC Kits.

We compared two kit methods for the enzymatic determination of plasma ammonia. The procedures involved measuring the decrease in absorbance at 340 nm resulting from the consumption of NADH in the Sigma kit, NADPH in the BMC kit. Both kits gave acceptable results for aqueous samples, but for plasma specimens values with the Sigma kit significantly exceeded those obtained with the BMC kit. In our hands, values with the BMC kit were more accurate and precise. On the basis of these results, we conclude that the BMC kit is the better choice.


Radioimmunoassay of serum myoglobin: evaluation and modification of a commercial kit and assessment of its usefulness for detecting acute myocardial infarction.

We evaluated a modified procedure for a commercially available myoglobin radioimmunoassay kit (Nuclear Medical Systems). Within-run and run-to-run precision was acceptable. Normal ranges were established and paralelism studies performed. Clinical usefulness was assessed in 100 consecutive patients admitted to our coronary-care facility. The determinations were done daily, along with creatine kinase and its isoenzymes, and lactate dehydrogenase and its isoenzymes. Fifty of the 100 patients ultimately were shown to have had acute myocardial infarction. Myoglobinemia was present in most of the patients with acute myocardial infarction, but information on its presence was less usefull clinically than was detection of creatine kinase isoenzyme MB.


Creatine kinase isoenzyme of high relative molecular mass in serum of a cancer patient.

We describe an atypical serum creatine kinase isoenzyme in the serum of a woman with cancer of the left breast. This isoenzyme migrated toward the cathode, closely following the MM isoenzyme on agarose gel electrophoresis. Its relative molecular mass was estimated to be about 325,000, fourfold that of normal creatine kinase. It is more heat-stable and is inhibited more by urea than the normal MM isoenzyme. Isoenzyme monomer B activity was observed to be 20 U/liter in the serum, as measured with use of an antibody against the M monomer. On anion-exchange column analysis, creatine kinase activity was observed only in the MM fraction, in spite of the fact that B activity was observed in the patient's serum. Results of the immunological investigation make it unlikely that the atypical isoenzyme is linked to immunoglobulin or beta-lipoprotein. It may have been present as the result of modification of normal creatine kinase by the therapeutic radiation the patient was receiving.